Electricity Equations Worksheet
Practice the core electricity equations with 10 problems covering Ohm's law, electrical power, charge, and energy. Full solutions included.
Equations you will need
| V = IR | Ohm's law: voltage = current × resistance |
| P = IV | Electrical power = current × voltage |
| P = I²R | Power dissipated in a resistor |
| Q = It | Charge = current × time |
| E = QV | Energy = charge × voltage |
| E = Pt | Energy = power × time |
Symbol key
| Symbol | Quantity | Unit |
|---|---|---|
| V | voltage / potential difference | V (volts) |
| I | current | A (amperes) |
| R | resistance | Ω (ohms) |
| P | power | W |
| Q | charge | C (coulombs) |
| E | energy | J |
| t | time | s |
Practice problems
Attempt each problem on paper first, then click Show answer to check your working.
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A 12 V battery drives 2 A through a resistor. Find the resistance.
Show answer
R = V/I = 12/2 = 6 Ω -
A 240 V appliance has resistance 60 Ω. Find the current.
Show answer
I = V/R = 240/60 = 4 A -
Find the power of a device drawing 3 A from a 230 V supply.
Show answer
P = IV = 3 × 230 = 690 W -
A 100 Ω resistor carries 0.5 A. Find the power dissipated.
Show answer
P = I²R = (0.25)(100) = 25 W -
Find the charge flow when 2 A flows for 30 s.
Show answer
Q = It = 2 × 30 = 60 C -
How much energy does a 60 W bulb use in 5 minutes?
Show answer
E = Pt = 60 × 300 = 18,000 J -
A current of 0.4 A flows through a 25 Ω resistor for 10 s. Find the energy dissipated.
Show answer
V = IR = 10 V; E = VIt = 10(0.4)(10) = 40 J -
A 2 kW kettle runs for 3 minutes. Find the energy used in kJ.
Show answer
E = Pt = 2000 × 180 = 360,000 J = 360 kJ -
Two resistors of 6 Ω and 12 Ω are connected in series across 18 V. Find the current.
Show answer
R_total = 18 Ω; I = V/R = 18/18 = 1 A -
A 9 V battery is connected to a 3 Ω resistor. Find the current, power, and charge passed in 1 minute.
Show answer
I = 3 A; P = 27 W; Q = 180 C
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About this worksheet
This electricity equations worksheet covers the essential equations for electricity & magnetism at the GCSE / A-Level level. Every problem has been written to mirror the style and difficulty of real exam questions, with full algebraic working shown in the solutions.
If you find these problems too straightforward, try the more advanced worksheets in the same topic listed above. If they feel too difficult, start by reviewing the equation definitions in the box at the top of this page and then return to question 1.