The sphere on the right has a charge of +2q. The sphere to the left has a charge of – 3q.

1. The sphere on the right has a charge of +2q. The sphere to the left has a charge of – 3q. Which of the following pictorial descriptions of the electric field best matches the above verbal description? 2 1 4 3

2. Jenny, a student in an introductory physics class sees the following equation: (1.6 x 10-5 C) (5.0 x 106 N/C) – 10 N = (0.015 kg) a Which of the following verbal descriptions best matches the above mathematical representation? • A proton is in electric field that experiences a 10 N force holding it back. • A 0.015 kg object experiences just one force due to a 5.0 x 106 N/C electric field. • A charged particle is accelerating in an electric field but also experiences a 10 N opposing force. • A particle with charge of 1.6 x 10-5 C is accelerated by a 10 N force.

3. +q x x x +q +q +q +q x Two charged spheres are brought together. The electric field measured at point A, points at a 45o angle North of West. Which of the following pictures below matches the above description? 3 1 A A A 2 x +√2q x

4. Vinit = 100 V Vfinal = 0 V A proton starts at rest between metal sheets with a potential difference of 100 Volts across them. Which motion diagram could match the proton’s motion when released? 1 2 3 4

5. Sarah is looking over her physics textbook and sees a situation described mathematically below. The same situation is described in words below. Decide which description fits the mathematical description best. • 3 x 1012 protons travel through a wire each hour. • 3 x 1012 electrons travel through a wire in each hour. • 3 x 1012 electrons travel through a wire in just under an hour. • 3 x 1012 Coulombs of charge travel through a wire in just under an hour.

6. A picture is drawn below showing equipotential surfaces for two fixed charged pith balls. Which of the following verbal descriptions best match the above equipotential surfaces? • Both pith balls are positively charged. • Both pith balls are negatively charged. • One pith ball is positively charged, the other is negatively charged. • Both 1 and 2 are possible solutions

7. A situation is described with an energy bar chart below. KoPEgoPEsoPEqoWKPEgPEsPEq DEint 0 Which of the following verbal representations best matches the above bar chart? • A charged object shoots straight up away from another charged object and reaches its highest point. • A charged object is high above the ground in an electric field. The field pulls the charged particle downward. We see the system’s energy when it is halfway down to the ground. • A charged object initially at rest moves at an angle away from a second like charged object. At the top of the projectile path the object is moving horizontally. • A proton is held below a negatively charged sphere and released.

8. -q3 +q2 +q1 y y y y x x x x Three identical magnitude charged spheres are shown below. Which electrical force diagram for objects corresponds to the pictorial representation? 3 1 4 2

9. A student sees in a textbook the picture below of two charged spheres and the corresponding electric field lines. Which of the following verbal descriptions best matches the above pictorial representation? • 1 The two spheres have charges that are opposite but equal in magnitude. • 2 The left sphere has a positive charge that is twice the magnitude of the negative charge on the right. • The left sphere has a negative charge that is twice the magnitude of the positive charge on the right. • 4 The right sphere must not have all of the lines drawn into it.

10. A positively charged sphere is held in a fixed position relative to a negatively charged sphere on the left with half the magnitude of electric charge. y y y y y y y y x x x x Which pair of electric force diagrams below best matches the above verbal description? 1 3 2 4

11. Four charged spheres, not necessarily the same magnitude charge, are placed at the corners of a square. The net electrical force on sphere C is zero. C A D B What are the signs of the charged spheres to match the above verbal description? A B C D 1 + – – + 2 – – – + 3 – – + + 4 + + + + 5 + – + –

12. Final Initial + + + + A process is shown in the picture below. The charged sphere on the right is fixed. The left charged sphere is on a moveable cart. It is initially held by a wedge, then let go. What energy bar chart best matches the pictorial representation? KoPEgoPEsoPEqoWKPEgPEsPEq DEint 1 2 3

13. A real situation is described mathematically: ½ m vo2 + q Vo = ½ m v2 + q V ½ (0.001 kg)(0 m/s)2 + (1.0 x 10-6 C)(12 V) = ½ (0.001 kg) v2 + (1.0 x 10-6 C)(0 V) The same situation is described verbally below. Which description fits the above mathematical description best? 1 A 0.001-kg object is moving between the plates of a capacitor at a constant speed. 2 A 1.0 x 10-6 C object initially moves at some speed v away from a 12-V plate until it comes to rest at a 0-V plate. 3 A 0.001-kg charged object that is initially at rest at a 12-V plate moves away from the plate to a place at zero potential. 4 The plate where the object arrives has no charge on it.