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Current, voltage and resistance – practice for Years 8–9

Sample questions on Current, voltage and resistance with the right answer and a worked solution, from easy to hard. In the Pickles Academy app a child gets new questions of the same kind every time, so they can't just learn the answers by heart.

Subject
Physics
Year
Years 8–9
Curriculum area
Electricity, magnetism and light

Question types: Using I = U / R

Rule: Current, voltage and resistance

I = V ÷ R, so V = I × R and R = V ÷ I. Current in amps (A), voltage in volts (V), resistance in ohms (Ω).

Example: R = 2 Ω, I = 2 A: V = 2 × 2 = 4 V

Watch out: Change milliamps first: 200 mA = 0.2 A.

Sample questions

  1. Question 1 Easy

    A current of 3 A flows through the resistor. What is its resistance?

    30 VR₁ = ?
    Show the solution
    Answer: 10 Ω

    How it works: Using Ohm’s law, R = U ÷ I = 30 V ÷ 3 A = 10 Ω.

  2. Question 2 Normal

    A current of 2.5 A flows through the resistor. What is its resistance?

    25 VR₁ = ?
    Show the solution
    Answer: 10 Ω

    How it works: Using Ohm’s law, R = U ÷ I = 25 V ÷ 2.5 A = 10 Ω.

  3. Question 3 Hard

    The resistors are connected in parallel. What is the total resistance?

    24 VR₁20 ΩR₂5 Ω
    Show the solution
    Answer: 4 Ω

    How it works: 1/R = 1/20 + 1/5 = 1/4; R = 20 × 5 ÷ (20 + 5) = 4 Ω.

Related topics

All Physics topics

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