Question 1
The figure shows two tiny 5.0-g spheres suspended from very light 1.0-m-long threads. The spheres repel each other after each one is given the same positive charge and hang at rest when
θ = 4.1°. What is the charge on each sphere? (
k = 1/4πε
0 = 9.0 × 10
9 N ∙ m
2/C
2)

◦ 89 nC
◦ 22 nC
◦ 45 nC
◦ 360 nC
◦ 180 nC
Question 2
A pair of charged conducting plates produces a uniform field of 12,000 N/C, directed to the right, between the plates. The separation of the plates is 40 mm. An electron is projected from plate A, directly toward plate B, with an initial speed of
v0 = 2.0 × 10
7 m/s. What is the speed of the electron as it strikes plate B?

,
melectron = 9.11 × 10
-31 kg)

◦ 1.8 × 10
7 m/s
◦ 2.1 × 10
7 m/s
◦ 2.4 × 10
7 m/s
◦ 1.2 × 10
7 m/s
◦ 1.5 × 10
7 m/s