Capacitors

Question 1

What is a capacitor?

Answer 1

Capacitors store electric charge, which creates a build up of electric potential energy

Question 2

How do capacitors work?

Answer 2

They are made in the form of two conductive metal plates connected to a voltage supply (parallel plate capacitor)
Electrons are transferred from one plate to another, creating a positive charge on one plate and a negative charge on the other. This process continues until the voltage across the capacitor equals the voltage of the power supply.
Electrons are also pulled off the other plate from the power supply, increasing the charge

Question 3

What is a dielectric?

Answer 3

A substance that is a poor conductor of electricity, but a good source for electric fields
It ensures charge does not flow across the parallel plates
- so a p.d can be created

Question 4

What is Capacitance, C?

Answer 4

The charge stored per unit potential difference (between the plates)
So the higher the capacitance, the more charge that the capacitor can store with the potential difference given

C = Q/V
Where C=Capacitance (Farads, F)

Question 5

How does electrical energy become stored within the plates of the capacitors?

Answer 5

The power supply ‘pushes’ electrons to one of the metal plates
- therefore doing work on the electrons and electrical energy becomes stored on the plates

Question 6

What happens as more and more electrons are put onto one plate?

Answer 6

The amount of charge increases, so when more electrons are added the electrons already there repulse against it, so more work done is needed to increase the charge

Leading to the potential difference across the capacitor increasing as well