Electric Current

B and E Blocks began their journey through the wild and wacky world of electric current. We discussed that nature of current, the difference between charge motion and conventional current, the concept of drift velocity and the features characterizing direct and alternating current. Make sure you can work with the basic current formula and recognize that current is a rate function - the rate of charge motion through a particular area. Tomorrow, B and E Blocks add the idea of electrical resistance to the growing descriptors of charge motion. B Block will do it with a lab focusing on Ohm's Law and E Block will walk through the concept in lecture.

C Block conducted their Ohm's Law lab in class today. Ohm's law relates potential difference (voltage), current and resistance and this relationship, for some substances, is constant. Written in terms of resistance, Ohm's Law states: R = V/I and a graph of voltage versus current should yield a linear relationship for which the slope is the resistance. For your resistors, this was definitely the case, but for the light bulb, the early and later sections of the graph had different slopes. Some substances are non-ohmic, they do not behave Ohm's Law across all ranges of input voltages. We'll discuss this in more detail later in this chapter. Have the write-ups for me tomorrow and you'll have time in class to work on test corrections. That's what F Block did today, so you'll get the same chance.