Shocking!

Honors Physics got a demonstration of the Tesla coil today, which is a fun way to demonstrate such concepts as capacitance, potential difference, electric potential energy and electric discharge. Here are a couple of photos of the spectacle:

We then reviewed capacitance and the basic nature of circuits before starting in on a discussion of series circuits. For series circuits, remember that charges must flow through each device in turn and any break in the circuit shuts down the entire circuit. As you work problems, keep in mind that the current in the circuit is the same across each resistor, the equivalent resistance is the sum of the resistor values and that the voltage drop across each device in the circuit varies and can be found using Ohm’s Law. We’ll check over your series circuit problems tomorrow before moving on to parallel circuits.

Physical Science B and E reviewed their lab investigations. We took each project in turn and worked through the discussion questions and calculations. We also took time to review the concepts of series and parallel circuits, in general, paying special attention to the patterns of current, voltage and resistance demonstrated by these circuits. Tomorrow, you’ll start on the next round of circuit construction, which will allow you to build more complex circuits and get an introduction to new circuit components.

Physics F and G picked up with electric current and a review of Ohm’s Law. Attention was then turned the rate of charge flow (current) and to factors that affect electrical resistance. We discussed examples of how material identity, length, temperature and cross-sectional area can be used to vary resistance and some practical applications/problems associated with these factors. Tomorrow, we add another electrical property of matter to our list – capacitance.

Homework

Honors Physics A: Practice 20A
Physical Science B and E: None
Physics F and G: Practice 19B, Conceptual Challenge p. 704 and the 19.2 Section Review

Rain and More Rain

Honors Physics discussed capacitors and their function in class and saw a demo of a capacitor in action. Tomorrow, you will see another demonstration of capacitors that will also highlight the concept of potential difference. We briefly turned attention to circuits and will go further with that concept in class tomorrow. Note, for #4 of the 18.3 Section Review, I’d take a look at page 671 for a helpful formula.

Physical Science B completed (mostly) their series and parallel circuit construction. Students had opportunities to see how series and parallel wiring affects not only resistors, but also batteries. Other circuit components can be part of series and parallel arrangements and you will look at some of these in coming projects. Tomorrow, we’ll go over this section of the lab unit and then move onto more specialized circuits.

Physical Science E conducted their series and parallel circuit lab investigation, which let them work with both the conceptual and mathematical aspects of circuit analysis. We will discuss this lab and the associated questions tomorrow and then move onto more complex circuits and specialized circuit components.

Physics F went over their Ohm’s Law lab investigation and then worked on test corrections for the light, reflection and refraction exam. Physics G started in directly on their test corrections. We’ll jump back into electricity tomorrow with a review of Ohm’s Law and the addition of another electricity-related property of materials: capacitance.

Homework

Honors Physics A: Practice 18C and 18.3 Section Review
Physical Science B and E: Complete lab questions
Physics F and G: Complete test corrections

Scheduling Update

Note for E Block: Stopped in by guidance after school and Mrs. Lane and I looked at my course recommendation forms. I had filled them out and she had checked them off, indicating she put them into the computer. Why this class didn't show up - Dunno. Likely, the file for this class didn't save properly, but it is no big deal. Mrs. Lane will fix the forms and all will be well in schedule land. She is going to put a copy of my list in my mailbox tomorrow, so I can write in your course number on your form.

Playing with Circuits

Honors Physics reviewed their light exams, Friday’s homework and then moved further into resistance. We discussed how certain factors such as temperature, cross-sectional area, length and material identity influence the resistance charges experience and related these factors to practical home applications. We started on capacitors next, with a definition of capacitance and a look at examples of capacitors. We’ll discuss capacitors tomorrow and demo how they function to store electric potential energy.

Physical Science B worked with the Snap Circuits kits to examine series and parallel circuits. Students built basic circuits with lamps, and more complex ones with motors and audio components. We’ll continue with this piece tomorrow and discuss the results before taking on more complex circuits and new components such as capacitors and diodes.

Physical Science E reviewed series and parallel circuits and took time to go over the math worksheet for this chapter. Attention then turned to the Snap Circuits kits and we previewed the type of work we will be doing over the next several days. Tomorrow, students begin constructing and evaluating series and parallel circuits.

Physics F conducted their Ohm’s Law investigation. Students tested a 50-ohm and 100-ohm resistor and found that the proportional relationship between voltage and current, when graphed, produced straight lines whose slope matched the tested resistor. The light bulb, however, was non-ohmic: the resistance at low voltages was lower than at higher voltages. The mystery resistor was definitely ohmic and folks found out pretty easily that it had a value of 68-ohms. That was verified by the banding pattern on the resistor that students interpreted using a chart and an iPhone app. Tomorrow, we’ll go into this lab in more detail and continue on discussing voltage, current and resistance.

Physics G reviewed Friday’s lab investigation and then moved into a general review of electric potential energy and potential difference. The function of a power source as a promoter of potential difference was described, as was the role of the power source to move charges from a low potential energy area to a high potential energy area. We’ll review this tomorrow, before tackling current and resistance. We’ll discuss these three specters for the remainder of the unit and they will also carry over to our work with magnetism.

Homework

Honors Physics A: None
Physical Science B: None
Physical Science E: Read Snap Circuits information packet
Physics F: Complete lab write up
Physics G: None

The Day of Fry

Honors Physics spent time discussion the results of the Ohm’s Lab and then moved into a review of potential difference. From this we added current and resistance to the mix and ended up at Ohm’s Law. The structure and function of batteries was also discussed and related to charge motion and DC current. On Monday, we will continue on with our examination of electricity with a discussion of factors affecting electrical resistance and properties of capacitors.

Physical Science B went over their electricity worksheet, which nicely covered the mathematical elements of the chapter. Then, we took time to preview our unit on circuit building by looking over the Snap Circuits kit, discussing proper use of the kit and safety and highlighting the types of components the kits contain. Students will start by examining series and parallel circuits and then move toward an examination of other circuit configurations/functions and the nature of special circuit components.

Physical Science E spent time working on their math worksheet for electricity. Make sure to carefully read each question/problem and have relevant resources at hand, such as your sheet that summed up properties of series and parallel circuits. We’ll go over this sheet on Monday and then preview our work with building circuits.

Physics F was introduced to the concept of electric potential energy and potential difference today and looked ahead to the other major players in the electricity game – current and resistance. On Monday, the investigation will target Ohm’s Law, which shows the relationship between current, voltage and resistance for many materials. Physics G conducted this lab today, with very good results. The linear relationship between voltage and current for the resistors was very clean and the slopes of the lines closely matched the stated values for the tested resistors. The light bulb did not demonstrate a linear relationship for the entire range of voltages – this is characteristic of non-ohmic substances. The LED lit only when the input and output wires were correctly connected. Diodes are often used to help direct current flow in circuits and do not allow the current to flow “backwards” through the circuit. We’ll talk more about diodes and other circuit components a little later on.

Homework

Honors Physics A: Complete 19B and the 19.2 Section Review
Physical Science B: None
Physical Science E: Complete electricity math worksheet
Physics F: Read lab protocol sheet
Physics G: Complete lab write up

My Hero!

Electricity for All

Honors Physics spent time working with Ohm’s Law in the laboratory. The rate of charge motion depends on the degree of potential difference to which it is exposed and the amount of opposition it faces moving through materials (resistance). For some materials, there is a constant, proportional relationship between voltage and current and these substances are said to be “ohmic.” Your resistors are constructed of ohmic materials and you produced clearly linear relationships for the entire range of tested voltages. The slopes of the lines were close matches to the stated resistances. For the light bulb, however, the ratio of voltage to current changed over the range of tested voltages. Light bulb filaments are “non-ohmic,” although they do follow Ohm’s Law quite well at higher voltages. Your LED’s are examples of diodes, which only allow current to flow in one direction. So, the LED lit when inserted one way in the circuit and didn’t when the polarity was reversed. Your motors allowed charge to move through regardless of how it was inserted into the circuit, but the direction the shaft turned changed when the motor was reversed. Tomorrow, we’ll talk more about the lab (including taking care of lab equipment/supplies) and continue on discussing potential difference and electric potential energy.

Physical Science B went over their Ohm’s Law lab and found that their resistors definitely followed Ohm’s Law. Very nice, straight lines were produced when voltage versus current was plotted by the computer, and the slopes of these lines were quite close to the values of the resistors you tested. The light bulb did not have so clear a linear relationship. The first few points on the graph had a markedly different slope than later points. Your bulb filament was non-ohmic., but Ohm’s Law could be used to predict the electrical properties at higher voltages. Then, students had the opportunity to practice the calculations associated with this chapter. We’ll go over the worksheet tomorrow and then turn attention to constructing and analyzing electrical circuits.

Physical Science E discussed electric power and electric safety. Electric power is not conceptually different than mechanical power – it is the rate at which the charges’ energy is used to do work. The unit for electric power is still the watt (W) and a device with more electrical power than another still doesn’t do more work than another; it simply does the work in a shorter amount of time. We then discussed the use of fuses, circuit breakers and ground-fault interrupters for electric safety. Tomorrow, math practice with circuits, Ohm’s law and electric power.

Physics F and G discussed the ability of charges to generate electric fields and forces. The use of Coulomb’s law to calculate the magnitude of electric force between two charges was examined and the use of field lines to represent electric fields was described. Tomorrow, G Block will conduct an investigation that will propel you towards our study of electric circuits by laying out one of the top gun relationships in electricity – Ohm’s Law.

Homework

Honors Physics – Complete lab write up
Physical Science B: Complete electricity worksheet
Physical Science E: None
Physics F: Complete Chapter 17 Chapter Review items #11-17, 19
Physics G: Read lab protocol sheet and complete Chapter Review #11-17, 19 for Monday

Its All About Charge

Honors Physics took a ride through electric fields and electric potential energy today. As I said, the journey through electricity will be a strange one, as we are going to omit a fair amount of material from the unit and may do things out of order. We found ourselves already in Chapter 18 today, after leaping over 90% of the math in and 40% of the information in Chapter 17. In Chapter 18, we are, again, going to leap over most of the math and only concentrate on the topics that will further a general understanding of static charge and electric current. The bulk of our time in this unit will focus on the more practical aspects of electricity and tomorrow’s lab on Ohm’s Law will let you see how the three main players in electric current, voltage, current and resistance, interact in ohmic and non-ohmic materials. This material in the book is farther ahead than we are currently, but our discussion of voltage today and the bit of reading to which I directed you will be sufficient to understand the theory behind your results. We’ll discuss the lab on Friday and continue on talking about batteries and charge motion.

Physical Science B did their own lab with Ohm’s law and saw clearly that certain materials maintain a very constant relationship between voltage and current throughout a wide range of voltages. For some materials, like the light bulb, the relationship is not the same at low voltages as for high voltages. The slopes of your lines for the resistors fell quite close to the stated values on your resistors, definitely within the resistor tolerances. We’ll discuss the lab in more detail tomorrow and the get some practice working on the mathematics of series and parallel circuits.

Physical Science E reviewed Ohm’s Law and series circuits today and then moved to parallel circuits. Parallel circuits provide multiple paths for charge flow and therefore, we would not expect the current to be the same through each path if the values of the resistance on the paths vary. However, we would expect the voltage across the resistors to be the same, and it would be the same as the potential difference of the power source. We took time to practice the math for parallel circuits and we will review this first thing tomorrow. Then, we’ll add in electrical energy, power and safety.

Physics F and G began their discussion of electricity with an overview of charge and the methods of charging materials. We spend a bit discussing static charge and then turn out attention to electric current. Like Honors Physics, we’ll be picking and choosing from the upcoming chapters, so make sure to pay close attention to your notes package – that will guide you as to the material for which you will be responsible on the assessment.

Homework

Honors Physics A: Read lab protocol sheet
Physical Science B: Complete lab write up
Physical Science E: Read 16.3 in your book and complete the 16.3 Section Review and the Practice on p. 551
Physics F and G: None

Ark II

For those who live in this area, the title of this post seems appropriate since it is, again, pouring rain. For those aged and infirm like myself, you might remember the Ark II tv show from the 1970's. Bad hair and cheesy tv...I loved the 70's!

Honors Physics began their examination of electricity today with a discussion on the nature of electric charge, the methods of generating charge and the forces that charged systems can produce. We contrasted friction, conduction and induction and examined how to use Coulomb’s Law to evaluate the strength of electric forces. We’ll look at electric fields tomorrow and relate those to the forces generated.

Physical Science B took a look at electric energy and electric power and related these topics to household concerns. We also took a good bit of time to discuss electric safety devices – fuses, circuit breakers and ground-fault interrupters – and how they are used in everyday life. Tomorrow, students will work on a lab that will allow them to examine how materials demonstrate adherence to Ohm’s Law. On Thursday, students will review their lab activity and then begin to work on the math associated with circuits and also start constructing circuits and investigating circuit components.

Physical Science E spent time reviewing series circuits and worked out how to calculate voltage, current and resistance for loads arranged in series. We’ll go over the two practice sheets that you were given in class at the start of the period tomorrow, address any issues and then move on to examine parallel circuits.

Physics F and G underwent their assessment experience for light, reflection and refraction. Tomorrow – Electricity!

Homework

Honors Physics A: Practice 17A
Physical Science B: Read lab protocol sheet
Physical Science E: Complete Ohm’s Law and series circuits worksheets
Physics F and G: Read section 17.1 in the textbook and complete Chapter Review items #1-10

Brand New Week

Honors Physics exercised their brains with their light (not lite) exam. Tomorrow, we’ll begin discussing electric charge and the forces that charged particles can generate.

Physical Science B reviewed the concept and math behind series circuits and then turned attention to parallel circuits. Series circuits offer only one option for charged particle travel; parallel circuits offer multiple possible paths that form complete circuits. For parallel circuits, the failure of one pathway does not stop charges from using the other paths to travel to and from the power supply. However, by adding more options, this actually lowers the resistance of the circuit. More devices hooked in parallel to a single power source means more current flowing through the circuit. More current, more resistance heating. This is how overloading a circuit in your home can lead to a fire. We worked practice problems quantifying resistance, voltage and current for parallel circuits and will discussing electric power and safety tomorrow.

Physical Science E reviewed their Ohm’s Law lab and folks’ data looked good. It was pretty clear that comparing the voltage provided and current produced through a single circuit gave the same value, and that corresponds with Ohm’s Law: R = V/I. Graphing voltage versus current gave very linear patterns with the slope of the resulting line falling within the tolerance limit for the given resistor. For the non-ohmic light bulb, current increased at a more rapid rate at the low voltages, but slowed its increase at higher voltages. This is why light bulbs burn out when you turn them on. The current coming through is high and the friction does a number on the aged filament. We didn’t have time for any more, since the assembly ran long. Tomorrow, we’ll delve more deeply into series circuits and then turn attention towards parallel arrangements.

Physics F and G Blocks reviewed for their exam on light, reflection and refraction. We walked through the chapter highlighting relevant material and making note of sections that we didn’t cover in much depth. You’ve seen the formula sheet many times, but may not have noticed that sign conventions are not presented. You need to have those fixed in your heads in order to successfully work the optics problems.

Homework

Honors Physics A: Read 17.1 and complete Chapter Review items #1-10
Physical Science B: Read 16.3 and complete the 16.3 Section Review and the Practice on pg. 551
Physical Science E: None
Physics F and G: Study for exam

It's a Trick! That's the Emperor!

Week Over, Man...Week Over

Honors Physics walked through the chapters covering light, reflection and refraction in preparation for Monday’s exam. Certain sections aren’t relevant for the exam and those were highlighted and areas known to give students trouble were identified. After Monday’s exam, we jump into electricity!

Physical Science B discussed series circuits in terms of function and mathematical analysis. Series circuits are easy to wire, but you do have do worry that if one item in the circuit ceases to function, the others will also since the electrons have to pass through every device in order to return to the power source. We then spent a good bit of time practicing how to calculate the equivalent resistance, current, total voltage and voltage drop across each device in a circuit. Remember that for a series circuit, the current through each device is identical, but the voltage drop depends upon the device’s individual resistance. We’ll review this on Monday and then turn attention to parallel circuits.

Physical Science E conducted a lab investigation on Ohm’s law. Students built simple series circuits with resistors or bulbs and switches to see how ohmic (the resistors) and non-ohmic (the light bulb) demonstrated Ohm’s Law. For the resistors, the graph of voltage versus current was a very nice straight line, for which the slope of the line was the resistance stamped on the resistor. For the light bulb, the graph was curved, indicating that the relationship between voltage and current was not linear and did not follow the predictions of Ohm’s Law. Monday, we’ll discuss the lab in more detail and delve further into series and parallel circuits.

Physics F and G began preparing for their exam, which we decided to reschedule to next Tuesday. F Block began by going over yesterday’s lab and highlighting the patterns of image formation by the converging and diverging lenses. Then, in both sections, students worked on a review sheet that targeted the math of this unit, specifically, the thin-lens/mirror equation, magnification formula and Snell’s Law. On Monday, we’ll go over the review worksheet you were given today and address any last-minute questions/problems. On Wednesday – electricity!

Homework

Honors Physics A: Study for exam
Physical Science B: None
Physical Science E: Complete lab write up
Physics F and G: Complete review worksheet

Hoverball Cat

Courtesy of Cute Overload - Proves that animal lovers can be scifi geeks, too...

Closing in on The Weekend

Honors Physics took time to review the worksheet from yesterday, that targeted topics about basic refraction, Snell’s Law and image formation by both converging and diverging lenses. Attention was then turned towards two refraction-dependent phenomena: total internal reflection and dispersion. The requisite conditions for light to demonstrate total internal reflection were described and applications of this phenomenon were discussed and demonstrated. Rainbow formation by prisms had previously been touched on, so additional time was spent discussing rainbow formation by water droplets in the atmosphere. The mechanisms behind rainbow formation were explained and variations of rainbows – the lunar rainbow or moonbow and double rainbows were illustrated. Tomorrow, bring all questions to class for the review to prepare for Monday’s exam.

Physical Science B and E began a discussion of circuits. Circuits allow us to direct charges to do the work that we need done by a device. We described the basic properties of an electrical circuit, contrasted open and closed circuits, described the function of a switch, explained the construction and importance of a schematic diagram and began to pull together ideas about series circuits. E Block will conduct a lab investigation tomorrow that will let students build a simple circuit in order to demonstrate the ability of different substances to obey Ohm’s Law. Later, students will have opportunities to build more complex circuits.

Physics F conducted their lab on converging and diverging lenses. The focal length for each lens was experimentally determined and the types and properties of images formed by each type of lens was investigated. Students used their experimental data to verify the thin-lens equation and the basic trends in image formation that we discussed in class. Tomorrow, we’ll discuss the lab in more detail and review for Monday’s exam.

Physics G discussed yesterday’s lab investigation on lenses and then began to study two refraction-dependent phenomena: total internal reflection and dispersion. Applications of total internal reflection such as diamond cutting and fiber optics were discussed and demonstrated and the formation of rainbows in the atmosphere was described. Tomorrow, bring along questions for review in preparation for Monday’s exam.

Homework:

Honors Physics A: None
Physical Science B: None
Physical Science E: Read lab protocol sheet
Physics F: Complete lab write up
Physics G: None

Glorious Wednesday

Honors Physics A took time to review refraction and lenses and discussed yesterday’s lab investigation. Since half of the class was absent due to a band function yesterday, time was allotted for students to share information and discuss the results of the lab with those who had conducted the lab activity. A review worksheet for lenses and refraction was distributed for students to work that will serve as part of the overall review for Monday’s exam on light, reflection and refraction. Make sure I have your lab write ups by Friday!

Physical Science B continued on with their discussion of electric current by adding the concept of resistance to the bag of knowledge. Resistance is a property of the material through which the charges move that is based on the material’s identity, temperature, length and cross-sectional area. We practiced using Ohm’s Law to solve problems about voltage, resistance and current and went over those at the end of the period. Tomorrow, we’ll take time to review the basic properties of electric current and start to talk about the structure and function of electric circuits.

Physical Science E picked up with the idea of the rate of charge flow – current. Current used in this sense refers purely to the amount of charge in coulombs flowing through a material per second and the unit of the ampere (A), can also be written as Joule/second. We then turned attention to electrical resistance and factors that affect resistance in materials. Ohm’s Law was introduced and used to evaluate relationships between voltage, current and resistance. We’ll use Ohm’s Law again when we tackle circuits, and your lab investigation on Friday will focus on ohmic and non-ohmic materials.

Physics F reviewed the concept of lenses, both converging and diverging and then turned attention to the phenomena of total internal reflection and dispersion. Demonstrations were presented for these topics so that students could better understand the general concepts. Tomorrow, you’ll get to practice working with lenses in your lab activity. Friday – review. Monday – exam.

Physics G conducted a lab investigation focused on the image forming abilities of converging and diverging lenses. Students determined the focal length of a converging and diverging lens and verified the patterns of image formation discussed in class and the use of the thin-lens and magnification formulas in problems solving. We’ll discuss the lab in class tomorrow and then explore the phenomena of total internal reflection and dispersion. Friday – review, Monday – exam.

Homework

Honors Physics A: Refraction and lenses review worksheet. Lab write ups by Friday
Physical Science B: 16.2 Section Review on page 545
Physical Science E: None
Physics F: Read lab protocol sheet and complete the 15.3 Section Review # 1, 3, 4
Physics G: Complete lab write up

That Big Orb in the Sky is the Sun

...in case you've forgotten...

Honors Physics worked with lenses in today’s lab investigation. Both converging and diverging lenses were examined and the images formed with objects at different distances from the focal length were investigated. The thin lens equation was pretty well verified and folks were able to experimentally determine the focal length of a diverging lens, so everyone went home happy. Tomorrow, we’ll go over the lab in more detail and spend time tidying up loose ends with lenses.

Physical Science B discussed yesterday’s lab investigation and effort was taken to make sure that everyone was able to thoroughly explain the results for each of the mini-activities. Attention was then turned to electric current. We contrasted static electricity and electric current and emphasized the role of electrical potential energy difference (voltage) in the generation of electric current. The structure and function of batteries was explained and dry and wet cells were contrasted. Tomorrow, we’ll review these ideas and push further into current with a more thorough discussion of amperage and resistance.

Physical Science E started the period by going over the Coulomb’s Law worksheet. Make sure that you can work these problems forwards and backwards. The skills you practice will also reinforce your ability to solve problems for gravitational forces. We then picked up the thread of electric current. The motion of charges due to a difference in electric potential energy between two locations is electric current and we examined how this potential difference (voltage) could be generated by batteries. Tomorrow, we’ll add more pieces to the current puzzle with amperage and electrical resistance.

Physics F and G reviewed over basic notions about refraction and then marched into lenses. Converging and diverging lenses were contrasted and the types of images formed by each was explored. The lab for this unit (on which G block will work tomorrow) centers around image formation by these lenses, so keep the book-learning in mind as you work through the experiments.

Homework

Honors Physics A: Complete lab write up
Physical Science B and E: None
Physics F: Complete Chapter Review items #15-19, 20, 23, 25, 26
Physics G: Read lab protocol sheet and complete Chapter Review items #15-19, 20, 23, 25, 26 for Thursday

Soggy Monday

An ark - get one...

Honors Physics reviewed basic ideas about refraction and Snell’s Law before moving to mirrors. Converging and diverging lenses were discussed and patterns of image formation for each type of mirror was diagrammed. Tomorrow’s lab will allow students practice working with both types of lenses and both the thin lens equation and the magnification formula.

Physical Science B had a very hard time in lab today, since it is a tremendously wet day and the lab focused on static electricity. On wet days, there is an abundance of water molecules in the air that work to neutralize charges that objects acquire. That is why static cling is worst on dry days. But, the basic ideas were visible – objects can acquire a charge through friction, conduction or induction and that the resulting forces can produce a change in the motion of objects. There was time in class, also, to review over the Coulomb’s Law problems that were assigned for homework.

Physical Science E completed their discussion of electric field lines and field-line diagrams and then spent time working problems for Coulomb’s Law. The solutions are presented in Friday’s post, so check your work to see how you did before coming to class tomorrow. We’ll review these problems tomorrow and then turn attention towards electric current.

Physics F and G completed their discussion of light polarization and then started in on the refraction chapter. Refraction will occur when light crosses from one medium to a different medium. The properties of the second medium determine light’s new speed and path of travel. Using Snell’s Law, that new direction can be predicted and time was taken in class to practice working problems with Snell’s Law. Tomorrow – finishing up refraction for G Block and on to lenses for F Block.

Homework

Honors Physics A: Read lab protocol sheet for tomorrow and complete Practice 15B for Wednesday
Physical Science B: Complete lab write up and rework Coulomb’s Law problems, if necessary
Physical Science E: Complete Coulomb’s Law worksheet
Physics F: Conceptual Challenge p. 565, Practice 15A and 15.1 Section Review
Physics G: Ch14 Chapter Review #40,44; read 15.1 and complete the 15.1 Section Review

Funkie Friday

Honors Physics reviewed their work on color and polarization and then moved into the area of refraction. The relationship between EM wave speed and density of medium was reinforced and used to explain the index of refraction. Snell’s Law uses this relative speed of light in various media to predict what would be the angle of a refracted ray, give the angle of the incident ray and identities of the two media. The fact that refraction is wavelength dependent helped explain the concept of dispersion and different materials were compared on how the various wavelengths of visible light were slowed down as they passed through. The homework tonight will allow you to ponder the consequences of refraction and practice solving problems using Snell’s Law. On Monday, we’ll start looking at lenses and Tuesday’s lab activity will concentrate on image formation by converging and diverging lenses.

Physical Science B went over their sound and light exam and then began to work problems using Coulomb’s Law. For those problems, remember to convert any charge value presented with a metric prefix to its full value in scientific notation before placing them in the formula. Also, some problems might not seem to give you full information (especially about charge), but a little thinking about the situation should allow you to see past that to the solution. For your worksheet, here are the answers so you can check your work:

1. 0.387 m
2. 0.585 m
3. 1.15 m
4. -143 N
5. 3.50 x 10^-4 N
6. 1.4 x 10^-3 N
7. 1.6 x 10^-19 C
8. 1.6 x 10^-19 C
9. 1.6 x 10^-19 C
10. 2.2 x 10^-17 C

Note: if you use 9 x 10⁹ N x m²/C² as your value for “k,” your answers may be slightly different than those above. Monday, you’ll get to work on a lab that will let you see the effects of static charge and the forces that result. Then, it will be on to electric current.

Physical Science E discussed their sound and light exams and then continued their discussion of static charge and the forces produced. Coulomb's Law was discussed, as was the concept of electric field lines. Students learned how to interpret field line diagrams and use them to predict electric field strength. On Monday, we will go over the review questions for this section and then take time to practice using Coulomb's Law to solve electric force problems.

Physics F spent time going over review work for light, reflection and mirrors and then turned attention to color and polarization. You should be able to recognize the primary colors of the additive and subtractive color systems and predict which colors would result as you mix pigments or light or shine light on a pigmented substance.

Physics G tied up loose ends for light, reflection and mirrors. We spent time reviewing the mathematics of mirrors and will begin our discussion of color and polarization on Monday.

Homework

Honors Physics A: Complete Conceptual Challenge p. 565, 15.1 Section Review and Practiced 15A
Physical Science B and E: Complete Coulomb’s Law worksheet
Physics F: Complete Conceptual Challenge p. 545 and Chapter Review items #37-44
Physics G: Complete Conceptual Challenge p. 545

Mirrors, Fields and Forces

Honors Physics spent time discussing color and polarization. The additive and subtractive color systems can be tricky to work with, so spend time really thinking about your answers to the homework questions. Polarization is relatively straightforward and today’s videos showed just how dramatic the effects of polarization can be. Tomorrow, we’ll review these concepts and then move on to the next chapter – refraction.

Physical Science B discussed electric charge, fields and forces. The final two methods for producing a an electric charge on a neutral object (conduction and induction) and discussed examples of each. Folks got a chance to visualize electric fields with field line diagrams and describe changes in electric potential energy based on position change of a charged particle in an electric field. Finally, the formula for Coulomb’s Law was presented and compared with that for gravitational force. Both forces are directly dependent on the magnitude of the property of matter generating the force (mass for gravity and charge for electric force) and inversely proportional to distance squared. You’ll get math practice tomorrow with Coulomb’s Law so don’t forget your calculator.

Physical Science E reviewed their static electricity experiments and began to explore the concept of static charge in more detail. The property of charge was described and related to the production of electric forces and fields. Methods of charging neutral objects was discussed and the basic properties of the three main subatomic particles (protons, neutrons and electrons) were reviewed. Tomorrow, we’ll take a more quantitative look at electric forces and fields before moving on to electric current.

Physics F and G had a final discussion of their lab activities and then turned attention back to the properties of mirrors. Plane mirrors were reviewed and the characteristics of convex and concave mirrors were introduced. The rules for drawing ray diagrams were presented and students got some practice seeing how these diagrams verified the mirror equation.

Homework

Honors Physics A: Conceptual Challenge p. 545 and Chapter Review items #37-45
Physical Science B and E: None
Physics F and G: None

Seeing the Light

Honors Physics took time to review the assignments pertaining to reflection and mirrors. It would be prudent to start laying a foundation in the brain as to the types of images and sign conventions associated with flat, concave and convex mirrors. Makes problem solving a lot easier. Tomorrow, we take on color and polarization, then it’s off to refraction.

Physical Science B got a reminder about the importance of the MCAS exam in June and we then headed into a discussion of the nature of charge and static electricity. We discussed the concept of fundamental charge, the ability of charge to produce forces of attraction and repulsion and started to describe methods of generating a charge on a neutral object. Remember, charge is produced on objects by an imbalance of positives and negatives. The negatively-charged electrons are the particle that is in motion when an object acquires a charge. We’ll continue discussing methods of generating charge tomorrow and begin to assess how to quantify the size of the electric force generated by charged objects – Coulomb’s Law.

Physical Science E participated in a lab investigation about static charge and the forces that charged objects can produce. Students were able to charge objects through friction, conduction and induction and see how the subsequent forces were able to influence the motion of matter. Electric force behaves like any force, the amount of acceleration produced on an object is directly proportional to the size of the force and inversely proportional to the object’s mass. We’ll discuss the lab in more detail tomorrow and use it to highlight our discussion of charge and static electricity.

Physics F and G worked on completing their lab investigations. Groups finished up with data collection and/or worked on the data analysis and lab write up. Tomorrow, we discuss the behavior of light when it reflects off of curved mirrors.

Homework

Honors Physics A: None
Physical Science B: None
Physical Science E: Complete lab write up
Physics F and G: Complete lab write up

However, Not An Acceptable MCAS Response

Without Bad Luck I'd Have No Luck At All

This weekend, the nicest of the year, was a total bust since I had a nasty cold and stayed indoors the whole time. My dogs are not happy with me at the moment and will likely exact their revenge in the near future…

Honors Physics reviewed Friday’s lab activity and then completed their discussion of mirrors. With mirrors, keep sign conventions in mind at all times with working with the mirror formula. Also, pay close attention when drawing ray diagrams for diverging mirrors or for converging mirrors when the object is within the mirror’s focal length. Those can get a little tricky if you’re not careful. Tomorrow, we’ll start with color and polarization and then its off to refraction.

Physical Science B and E endured their graded learning experience for sound and light. Tomorrow, we jump into the concepts of charge, electric potential energy and static electricity. E Block will conduct a lab investigation centered on static electricity and the forces produced when charged objects are brought together.

Physics F worked on their light lab investigations. Reflection by plane and curved mirrors was examined, as was the polarization of light and reflectivity of different surfaces and colors. Physics G worked on a reduced version of this lab, concentrating only on reflectivity and polarization. It was found that both color and texture affect reflectivity and that the intensity of light passing through a polarizer and analyzer could be predicted using Malus’s Law. For mirrors, plane mirrors verified the law of reflection and formed only virtual images, concave mirrors could form both real and virtual images and convex mirrors were, like plane mirrors, restricted to forming virtual images. A couple of groups in both blocks didn't get to finish collecting the data, so I'll allow some time at the beginning of class tomorrow for them to wind up their labs. The lab write ups will, therefore, not be due tomorrow.

Homework

Honors Physics A: None
Physical Science B: 16.1 Section Review, Chapter Review items # 13, 22, 29, 30
Physical Science E: Read lab protocol sheet and complete 16.1 Section Review and Chapter Review items #13, 22, 29, 30
Physics F: None
Physics G: None

Happy FryDay

Honors Physics conducted a lab investigation centering on mirrors, reflection and polarization. Plane mirrors were investigated to validate the law of reflection and the pattern of image formation was described. Students then worked with convex and concave mirrors to assess what types of images these mirrors could form. For polarization, students examined Malus’s law, which allows one to predict the intensity of light passing through a polarizing filter system based on the angle of the polarizer. Students found that light intensity decreases steadily as one polarizer is rotated with respect to a second, with maximum extinction occurring when the polarizers are at 90 degrees. The overall data supported Malus’s law, which further supports the model of light as a transverse wave.

Physical Science B and Physical Science E reviewed for Monday’s exam on sound and light. We walked through the chapter, reviewed study materials and answered any questions that still plagued folks. Starting Tuesday – Electricity!

Physics F and G began their discussion of light and reflection. We described the dual nature of light and then moved to the basics of reflection. Specular and diffuse reflection were contrasted and described based on the law of reflection. The, attention turned to plane mirrors and the formation of virtual images. On Monday, G Block will engage in a lab activity that will allow them to explore both plane and curved mirrors, while F Block begins to discuss how curved mirrors produce images.

Homework

Honors Physics A: Complete lab write up, the 14.3 Section Review and Practice 14B (only do ray diagram for first two problems)
Physical Science B: Study for sound and light exam
Physical Science E: Complete review packet and study for sound and light exam
Physics F: None
Physics G: Read lab protocol sheets

This is Too Cool

Popular Science has scanned in its back issues (its been around 137 years, so that's a lot of titles) and has made the archive FREE to search online! You can't just browse issues, yet, but when you do a search and choose an article to read, you get the whole issue, so you can look through the whole thing. This is an amazing resource of scientific initiative - bookmark the site.   NOW!

Popular Science Archives

Enough is Enough

Though it was just a little and it didn't stick, seeing snow today was not a happy-making experience. Time for sunshine. Buckets and buckets of sunshine...

Honors Physics went over yesterday’s sound exam and then moved into the light. We started out by describing the general properties of light (as per the wave model), the components of the electromagnetic spectrum, Huygen’s ideas about light propagation, reflection and plane mirrors. A lot of this was covered back in the vibrations and waves chapter, so we were able to move through that material at a pretty fast clip. Tomorrow, you will get a chance to work with plane mirrors and also with convex and concave mirrors. We said that plane mirrors make virtual images that are the same size and orientation as the object and appear as far behind the mirror as the object is in front of the mirror. It is a different ballgame with curved mirrors….

Physical Science B conducted a lab investigation with lenses to study refraction, image formation and magnification. Using a biconvex lens, students made real and virtual images, determined the focal length of the lens and calculated magnification for the various images formed. The results of the lab were good! Students were clearly able to see the pattern of image formation as an object moved closer and closer to a lens and the result when an object was placed at the focal length and within the focal length. Further, the calculate focal lengths coincided nicely with that experimentally determined at the beginning of the investigation. We’ll go over the lab tomorrow, so make sure you have completed the lab write up. Time will also be spent reviewing refraction and dispersion before starting the general chapter review in preparation for Monday’s exam.

Physical Science E discussed dispersion of light by prisms and raindrops. Rainbow formation was explained, as were the variations of the simple rainbow: multiple rainbows, full rainbows and moonbows We then turned attention to starting the review for Monday’s exam on sound and light. Make sure to come with any final questions tomorrow so that we can get you squared away before the test.

Physics F and G spent time correcting their sound exams. Light and reflection begins tomorrow…

Homework

Honors Physics A: None
Physical Science B: Complete lab write up and review worksheet packet
Physical Science E: None
Physics F and G: Complete test corrections

Halfway to Friday

Honors Physics, Physics F and G all suffered through exams in the area of sound. Tomorrow, each class begins their unit on light with an over view of light and reflection. We’ll hit refraction and lenses in the next chapter, but will likely hop over diffraction and interference to make sure that we have sufficient time for electricity and magnetism.

Physical Science B completed their sound and light material with a discussion of refraction, lenses, dispersion and prisms. A refraction tank was used to demonstrate the diffraction of light as it passed between air and water and how light incident at an angle greater than the critical angle displayed total internal reflection. We looked at a natural fiber-optic material (ulexite) and discussed the use of fiber optics in the communications industry. Lastly, we described how prisms promoted dispersion and how water droplets in the atmosphere, functioning as prisms, create rainbows. Tomorrow, a lab on lenses, magnification and image formation.

Physical Science E had about the same day as B block, but did not make it as far as full coverage of prisms and dispersion. We’ll complete that discussion tomorrow and you will get to see rainbow formation by prisms. We’ll start our sound and light review, which we will complete on Friday in preparation for Monday’s exam.

Homework

Honors Physics A: 14.2 Section Review and Chapter Review items #6, 8, 12
Physical Science B: Read lab activity p. 524-525
Physical Science E: 15.4 Section Review
Phsyics F and G: Chapter Review #1-13

A Sound Review

Honors Physics spent the period reviewing for tomorrow’s exam for sound. The mixed review worksheet was covered and students will turn it in tomorrow, so that they have it as a study resource tonight. Thursday – Light!

Physical Science B reviewed ideas about reflection and color and began to work through the concept of refraction. We will get into refraction more deeply tomorrow and begin a discussion of lenses. Thursday’s lab investigation will target image formation by lenses and should leave us with a little time to review the lab and refraction, in general. Friday, dispersion and a basic review. Monday – exam.

Physical Science E went over yesterday’s lab activity and then took time to review basic ideas about light and reflection. Tomorrow, we will begin our discussion of refraction and total internal reflection. Then, we tackle lenses and prisms. Then…review. Then…..Exam!

Physics F and G went over their mixed review worksheets and then proceeded to crawl through the chapter, highlighting important concepts and review problem solving techniques. Tomorrow, exam. Thursday, starting light and reflection.

Homework

Honors Physics A, Physics F and G: Study for exam
Physical Science B and E: None

A Quiet Monday

What can one say about a day like Friday? Pretty much everyone had a horror story about power outages, property damage or overall chaos to describe. Thankfully, folks are in the process of getting back to normal and we got an unexpected 3-day weekend as a bonus.

Honors Physics finished up their sound material with a discussion of beats. Alternating areas on constructive and destructive interference produced by waves of different frequencies arriving at the ear at the same time. By counting the beat frequency, one can determine how many hertz the notes are apart. Time was given in class to work on the mixed review sheet for the chapter in preparation for tomorrow’s exam review. Bring all questions with you tomorrow as we prepare for Wednesday’s sound exam.

Physical Science B watched a video on color and light that nicely summarized the light topics to date. Tomorrow, we’ll go over the homework for reflection and color and then turn out attention to refraction and diffraction.

Physical Science E conducted their lab investigation on light reflectivity, polarization and intensity. As for B Block, the data demonstrated that color and texture have an effect on reflectivity, polarizing filters show maximum reduction in light intensity when oriented at 90 degrees to each other and light intensity decreases with distance with an inverse-square relationship. Tomorrow, we discuss the lab and then move on to refraction and diffraction.

Physics F and G reviewed harmonics and beats and then worked on review material for the chapter. Tomorrow – full period exam review. Wednesday – exam. Thursday – moving on to light and reflection.

Homework

Honors Physics A: Complete mixed review worksheet
Physical Science B: Complete 15.3 Section Review, Math Skills p. 519 and Chapter Review items #22-25
Physical Science E: Complete lab write up
Physics F and G: Complete mixed review worksheet