Electric Fields

Question 1

Explain why the time to fall vertically between two parallel plates is independent of the mass of a particle.

Answer 1

→ force = mg
→ a = f/m, a=g
→ time only depends on acceleration and distance

Question 2

Explain horizontal acceleration between two plates of a particle differs for each particle.

Answer 2

→ a = Eq/m
→ E stays constant but mass and charge vary for each particle

Question 3

Explain why energy increases in a capacitor when the dielectric is pulled out.

Answer 3

→ dipoles in dielectric line up along field lines making one plate -ive & other +ive
→ attractive forces between the dielectric and plates
→ work is done to overcome this force

Question 4

What is meant by dielectric constant?

Answer 4

Dielectric constant is = permittivity of medium/
permittivity of free space

Question 5

Explain why the capacitance changes when a dielectric is inserted.

Answer 5

→ dipoles in dielectric line up along field lines making one plate -ive & other +ive
→ this reduces the electric field between the plates so voltage decreases
→ as charge stays the same, C increases

Question 6

State what is meant by an electric field.

Answer 6

force per unit charge acting on a +ive charge

Question 7

Define the term electric potential at a point.

Answer 7

work done per unit charge to move a small positively charged particle from infinity to that point

Question 8

State what is meant by the potential gradient.

Answer 8

change in potential per unit distance at that point