Answer to Question #102126 in Physics for Madi

Question

Oppositely charged parallel plates are separated by 53.3 mm. A potential difference of 6000 V exists between the plates.
a) What is the magnitude of the electric field, E, between the plates; see Figure (A) below
An electron is placed in the middle of the parallel plates; see Figure (B) above.
b) What is the direction of electric force applied on the electron?
c) What is the magnitude of the force on the electron?
d) What is the kinetic energy when the electron moves from rest to reach the plate?
e) What is the speed of the electron when it hits the plate?
f) What is the acceleration of the electron?
g) What is the time interval for this motion?

Answer 1

a)

$$E=\frac{U}{d}=\frac{6000}{0.0533}=112570.4\frac{N}{C}$$

b) To the right.

c)

$$F=eE=(1.6\cdot10^{-19})112570.4=1.8\cdot10^{-14}N$$

d)

$$K=eU=(1.6\cdot10^{-19})6000=9.6\cdot10^{-16}J$$

e)

$$v=\sqrt{\frac{2K}{m}}$$

$$v=\sqrt{\frac{2(9.6\cdot10^{-16})}{9.1\cdot10^{-31}}}=4.6\cdot 10^7\frac{m}{s}$$

f)

$$a=\frac{F}{m}$$

$$a=\frac{1.8\cdot10^{-14}}{9.1\cdot10^{-31}}=2\cdot10^{16}\frac{m}{s^2}$$

g)

$$t=\sqrt{\frac{2d}{a}}$$

$$t=\sqrt{\frac{2(0.0533)}{2\cdot10^{16}}}=2.3\cdot10^{-9}s$$