Electricity

Question 1

Current formula

Answer 1

I = Q/t

Question 2

Kirchhoffs current law

Answer 2

The current into a junction is the same as the current out

Question 3

Kirchhoffs voltage law

Answer 3

The sum of all voltages round a circuit must equal zero

Question 4

Voltage formula

Answer 4

V = w/Q where w = energy transferred

Question 5

Electrical power formulas

Answer 5

P = energy/time 
P = IV

Question 6

Resistance

Answer 6

Series R = R1 + R2 …

Parallel R = 1/R1 + 1/R2 …

Question 7

Factors affecting resistance

Answer 7

Diameter of wire / cross sectional area
Length of wire
Material of wire
Temperature

Question 8

Resistivity formula

Answer 8

e = Ra/l
e = resistivity 
R = resistance 
a = cross sectional area 
l = length

Question 9

What does a potentiometer do?

Answer 9

Alters the PD round the circuit

Question 10

Drift velocity formula

Answer 10

I = navq
I = current
v = drift velocity 
a = cross sectional area
n = charge density 
q = charge

Question 11

PD

Answer 11

energy transferred per unit charge between 2 points

Question 12

EMF

Answer 12

energy supplied per unit charge by the supply

Question 13

Terminal PD

Answer 13

energy transferred per unit charge to the load (external circuit)

Question 14

R

Answer 14

load resistance

Question 15

lost volts

Answer 15

energy transferred per unit charge as the electrons flow through the cell

Question 16

r

Answer 16

internal resistance