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GCSE Physics units and standard form

Convert metric prefixes, grams and squared or cubed units; write numbers in standard form.

Practise

Current calculation

A charge of 5 mC passes a point in 4 s. Calculate the average current in A using I = Q / t. Give your answer to 3 significant figures.

Treat the given values as exact unless an uncertainty is stated.

Use decimals or e notation, e.g. 4.2e-3. Enter the unit separately.

Hint

Convert mC to C before dividing by the time in seconds.

Worked solution
  1. Q = 5 × 10-3 C.
  2. I = Q / t = (5 × 10-3) / 4 A.
  3. I = 1.25 × 10-3 A (3 significant figures; trailing zeros may be omitted in your entry).
Another question
Question type: Mixed practice
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Foundation and Higher: this set covers content common to both tiers. Some calculations need several steps.

Units and powers

This set uses nano, micro, milli, centi, kilo and mega. A prefix on a squared or cubed length applies to every length factor: 1 cm³ = (0.01 m)³. The SI base unit for mass is kg. Standard form has a coefficient from 1 inclusive to 10 exclusive.

GCSE scope

AQA 8463: MS 1a–b, 3c, 5c; 4.2.1.3; OCR Gateway J249: 5e Units; 5g M1a–b, M3c, M5c; P3.2. Tasks cover the selected skills listed above.

AQA specification · OCR Gateway specification

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