Electric Forces and Fields

B Block jumped into the arena of electric forces today. We tied up some loose ends from yesterday with a discussion of methods of charging neutral objects, then turned towards Coulomb's Law. We looked at the factors influencing the magnitude of electric forces (charge and distance) and how to assess the direction of a force on a single charge. We then layered on some complexity by looking at systems with multiple charges and how to determine the equilibrium position for a charge placed in a linear system. We'll go over these in class tomorrow, but don't forget to check out the videos in the last post for some help if you get stuck. E and F Blocks had more practice with Coulomb's Law and how to work with multiple charges arranged in a line. A little time was given for students to challenge themselves by finding the net force on a charge where the neighboring charges are not on a nice, tidy line. Tomorrow, electric fields! E Block reviewed their electric forces problems and more practice was given for those problem types, since vector operations are also going to come in to play with electric fields. Some folks didn't write down #3, so make sure you can solve for the equilibrium position of a -8μC charge placed between a 15 μC and a 3 μC charge that are 1.2 meters apart. The solutions for those problems (check yesterday's videos if you're still stuck):

1. • -4 μC charge: 2.4 x 10³ N along positive x-axis
   • 7 μC charge: 2.2 x 10³ N along negative x-axis
   • -2 μ charge: 235 N along negative x-axis
2. 1.86 x 10^-5 N; 9.95° above negative x-axis
3. 0.83 m from 15 μC charge