SP212
Worksheet 2
Ch 22.(1-3) Electric Fields
Problem 1
A proton has a mass of m = 1.67 × 10−27 kg and a charge of q = +1.61 × 10−19 C. This proton is
placed into a uniform electric field of magnitude 2.5 × 109 N/C.
a) What is the force from this electric field acting on the proton?
b) If the proton starts from rest, how long will it take to reach 1/10th of the speed of light (3 × 108
m/s)?
c) How far does the proton travel in this time?
HINT: You will need the kinematic equations of motion for constant acceleration: v = v0 + at
and x = x0 + v0 t + 21 at2 .
This problem is relevant for HW L2 problems 2 and 62.
Problem 2
A particle with charge q1 = +6 nC is placed at the origin of the xy plane. Another particle with
charge q2 = −6 nC is placed on the y axis 5 cm above the origin.
a) At the point (2.5 cm, 2.5 cm), in which direction does the net electric field due to these two
charges point?
b) What is the magnitude of the net electric field at the point(2.5 cm, 2.5 cm)?
TIP: You will have the think about the components of the electric field due to each point charge.
This problem is relevant to HW L2 problems 7 and 19