6.1 capacitors

Question 1

what is a capacitor

Answer 1

device used to store charge
two parallel metal plates with an insulator material between them

Question 2

capacitance equation

Answer 2

C = Q/V

Question 3

unit of capacitance

Answer 3

farad F

Question 4

formula for capacitors in series

Answer 4

1/CT = 1/C1 + 1/C2 + 1/C3

Question 5

formula for capacitors in parallel

Answer 5

CT = C1+C2+C3

Question 6

how can the energy stored be found from a Q against V graph?

Answer 6

area under the graph

Question 7

examples of circuits where capacitors are used

Answer 7

flash camera, large current required for a short amount of time. smoothing circuit

Question 8

what do graphs of I,V,Q against t look like for a discharging capacitor?

Answer 8

exponential decay curves

Question 9

what is the area under the I-t graph equal to?

Answer 9

charge that has flowed off the capactor, so was originally stored on it

Question 10

what is the time constant of a capacitor discharge circuit?

Answer 10

time taken for I,Q,V to fall to 1/e its original value - 37%

Question 11

what is the formula for calculating time constant?

Answer 11

t = RC