Edexcel IGCSE Physics Electricity units questions

Electricity units syllabus

Questions on electricity units can test recall, calculations, explanations, diagrams, data handling and practical skills. You should be able to:

• 2.1 use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V) and watt (W)

How to answer electricity units questions

1. Write the unit symbol exactly and distinguish quantities that use similar-looking units.
2. Convert prefixes and compound units before substituting values into an equation.
3. Check that the unit of the final answer matches the quantity asked for.
4. Use the context of a diagram or calculation to reject units with the wrong dimensions.

Electricity units example questions and worked answers

These examples show how information in a diagram, graph or experimental context becomes part of a complete exam answer.

Example 1: Using a Diagram

Question 1

This question is about electrostatics. A student uses a plastic rod to investigate electrostatics. The student uses a meter to measure the amount of charge on the rod.
The meter displays a reading of –5.2mC.
Which of these is the same as –5.2mC?

A –0.52C

B –0.052C

C –0.0052C

D –0.00052C

Final answer

C –0.0052 C

Mark scheme points

1. M1 Selects C, –0.0052 C.

Explanation

The prefix milli means \(10^{-3}\), so convert millicoulombs to coulombs by multiplying by \(0.001\).

–5.2 mC = –5.2 × 10⁻³ C
        = –0.0052 C

The negative sign is unchanged.

Common mistakes

• Using \(10^{-2}\) instead of \(10^{-3}\) for the prefix milli.
• Moving the decimal point the wrong number of places.
• Dropping or changing the negative sign during the conversion.

Example 2: Using a Diagram

Question 2

This question is about electrostatics.

*P65067A0520* Turn over

5

A student uses a plastic rod to investigate electrostatics.

The student uses a meter to measure the amount of charge on the rod.

The meter displays a reading of –5.2mC.

Which of these is the same as –5.2mC?

A –0.52C

B –0.052C

C –0.0052C

D –0.00052C

Final answer

C: −0.0052 C

Mark scheme points

1. M1 Selects C (−0.0052 C).

Explanation

The prefix milli means 10⁻³, so:

−5.2 mC = −5.2 × 10⁻³ C
       = −0.0052 C

Therefore, the correct choice is C.

Common mistakes

• Forgetting that m means milli, or 10⁻³.
• Moving the decimal point in the wrong direction when converting from mC to C.
• Changing the negative sign; the charge remains negative after conversion.

Practise Electricity units questions

Build a focused practice set from this part of the Edexcel IGCSE Physics syllabus.