6.1

Question 1

Capacitor

Answer 1

Circuit component that stores energy by separating charges onto two electrical conductors with an insulator between them.
One plate +ve, one -ve

Question 2

Capacitance

Answer 2

The quantity of charge which can be stored per unit potential difference across the plates of the capacitor

Question 3

Farad

Answer 3

Unit of capacitance, 1 farad is 1 coulomb per volt

Question 4

Charge transferred in a capacitor is effected by

Answer 4

Permittivity of dielectric (insulating material), plate separation, plate area overlap

Question 5

How is energy stored in a capacitor

Answer 5

It is the work done in separating charges on the 2 plates

Question 6

How does the rate of charging/discharging a capacitor change?

Answer 6

Discharging: the more charge on the plates, the faster they can discharge, as more charge is transferred, discharge becomes slower
Charging: vv

Question 7

Use of capacitors

Answer 7

Only used to store small amounts of energy, very quick release of charge: camera flash,
Back up power/emergency current supplies

Question 8

Formula for exponential decay

Answer 8

Discharging:
X=X•e^(-t/RC)
Charging:
X=X•(1-e^(-t/RC))

Question 9

Time constant

Answer 9

Tao = RC

Time for charge on a capacitor to decrease to 37% of initial value (1/e = 0.37)