M6.2 Capacitors

Question 1

what is a capacitor and what is it made of

Answer 1

electrical component that stores electrical charge
two conducting plate seperated by a gap/insulator

Question 2

explain how a capacitor is charged

Answer 2

connected ot a power source
build up of electrons one side of the capacitor
due to insulator charge cannot pass between the pates
PD builds up between the plates

Question 3

explain how current changes through charging

Answer 3

current starts high
as charge builds up harder for electrons to be left
when PD accross the Capacitor = P.D accross the cell – current is 0

Question 4

hwo does current change when discharging

Answer 4

initially high
as charge is lost from the Cpacitor current decreases as voltage accross the capacitor decreases

Question 5

define capacitance

Answer 5

capacitance is a measure of the amount of charge taht can be stored per unit P.D
how good it is at storing charge

Question 6

Example uses of capacitors

Answer 6

Flash photography
Back-up power
Smoothin out AC –> DC conversions

Question 7

Why use a capacitor

Answer 7

faster time to charge or discharge compared to batteries

Question 8

how does capacitance add up when Capacitors are in series

Answer 8

1/Ctotal = 1/c1 +1/c2 ….

Question 9

define the time constant in Capacitors

Answer 9

The time constant is the amount of time needed to pass for the charge or voltage or current to have dropped down to 37% its maximum

Question 10

which equation is used when measuring charge or voltage discharging

Answer 10

X =X0(e^-t/CR)

Question 11

which equation is used when measuring charge or voltage charging

Answer 11

X = X0(e^-t/CR)