Electricity Equations

Question 1

What is the equation for Ohm’s Law?

Give units

Answer 1

V=IR

Voltage = current x resistance

Volts = Amperes x Ohms

V
I R

Question 2

State the equation linking current and charge

Give units

Answer 2

Q = I x t

Charge = current x time

Coulombs = Amperes x seconds

Q
I t

Question 3

State the equation linking work done, Charge and Voltage

Give units

Answer 3

W = QV

Work done = charge x voltage

Joules = Coulombs x Volts

W
QV

Question 4

State the equation for resistance in a series circuit

Answer 4

R_total = R₁ + R₂ + R₃

Question 5

State the equation for resistance in a parallel circuit

What do you have to do to find the final answer?

Answer 5

1/ R_total = 1/R₁ + 1/R₂ + 1/R₃

Invert

Question 6

State the equation linking power, current and voltage

Give units

What is this used for?

Answer 6

P = IV

Power = current x voltage

Watt = amp x volt

P
I V

Used to find the rating of a fuse