Chapter 21 - Capacitors

Question 1

what is a capacitor

Answer 1

electrical component which stores charge on 2 separate metallic plates

Question 2

what is capacitance

Answer 2

charge stored per unit potential difference, across two plates

Question 3

capacitance unit

Answer 3

farads

Question 4

capacitance in series equation

Answer 4

1/ct = 1/c1 + 1/c2

Question 5

capacitance in parralel equation

Answer 5

ct = c1 + c2

Question 6

area under charge p.d. graph

Answer 6

energy stored by the capacitor

Question 7

time constant

Answer 7

time it takes for the charge in the capacitor to reduce by 37%

Question 8

factors affecting time taken for a capacitor to charge or discharge

Answer 8

• capacitance of the capacitor (affects amount of charge which can be stored)
• resistance of the circuit (affects how quickly current flows - hence how quickly the capacitor charges/discharges)

Question 9

capacitance formula

Answer 9

C = Q / V

Question 10

how to calculate time constant

Answer 10

resistance x capacitance

Question 11

how can a capacitor be discharged

Answer 11

disconnecting the power supply and connecting up another electrical component which can be done via switch