Electric fields

Question 1

Define

electric field strength

Answer 1

The force per unit positive charge acting on a stationary positive charge at that point

Question 2

How do you calculate electric field strength?

Answer 2

p.d. across plates / plate separation

E = V/d

E = F/Q

(measured in V m^-1 or N C^-1)

Question 3

How do you calculate the force on a charge in a uniform electric field?

Answer 3

F = QE = QV/d = eV/d

Question 4

An electron travels between two plates in a uniform electric field and reaches the opposite plate at v m s^-1

How will this speed change if the uniformity of the field is changed?

Answer 4

The speed will not change as the speed only depends on the potential difference across the plates.