Capacitors

Question 1

All versions of energy in capacitor

Answer 1

E = 1/2 QV
E = 1/2 CV^2
E = 1/2 Q^2/C

Question 2

Energy, Charge, Voltage (normally)

Answer 2

E = QV

Question 3

charge time current

Answer 3

Q = IT

Question 4

energy, ITV

Answer 4

E = ItV

Question 5

Farad meaning

Answer 5

amount of charge stored per unit voltage

Question 6

Adding capacitance in parallel vs series

Answer 6

Parallel - Normal
Series - Reciprocal

Question 7

Parallel capacitors distribution and constants

Answer 7

Voltage same
Charge shared and proportional to capacitance

Question 8

Series capacitors distribution and constants

Answer 8

Charge same
Voltage shared and inversely proportional to capacitance

Question 9

Discharging (V, Q, I)

Answer 9

V = V0e^-t/RC
Q = Q0e^-t/RC
I = I0e^-t/RC

Question 10

Time constant meaning

Answer 10

Time taken for charge (&pd &current) to drop by 1/e

Or time taken for it to charge to get to (1-1/e)

Question 11

time constant equation

Answer 11

τ = CR

when time is time constant:
V = V0 e^-1

Question 12

halving time, time constant

Answer 12

H.t = ln(2) τ

Question 13

Charging capacitor equation

Answer 13

Vc = Vo (1- (e ^-t/RC))

Vc is voltage across capacitance
Vo is cell voltage

Question 14

Charging capacitor equation (resistor voltage)

Answer 14

Vr = Vo (e ^-t/RC)

Vr is resistor voltage
Vo is cell voltage

Question 15

current, charging capacitor

Answer 15

Current goes down as capacitor charges

I = Io e^-t/RC

Question 16

finding time for capacitance to decrease by a proportion

Answer 16

V/Vo = e^-t/RC

where V/Vo is the ratio of how much it decreased

Question 17

Capacitance physical things equation

Answer 17

C = (εr εo A)/d

Question 18

material put in middle of capacitor name

Answer 18

dielectric

Question 19

increase distance when battery connected energy

Answer 19

energy decrease

Question 20

increase distance when battery disconnected energy

Answer 20

energy increase

Question 21

p

Answer 21

x10 ^ -12

Question 22

n

Answer 22

10 ^ -9

Question 23

M

Answer 23

10 ^ 6

Question 24

Electric field equation

Answer 24

E = v/d

Question 25

Electric field force equation

Answer 25

F = QxV / d

Question 26

How polar molecules work in dielectric

Answer 26

• negative side aligned facing positive plate
• reducing electric field
• V reduces, Q constant so C increases because of equation