Electric charge and current

Charge interactions, current, Q = It, e.m.f., potential difference, resistance and wire dimensions.

SEC G2 Science Physics component 2027

Learning goals

state that there are positive and negative charges and that charge is measured in coulombs
state that unlike charges attract and like charges repel
State current as rate of charge flow measured in amperes
Distinguish conventional current from electron flow
Apply charge equals current multiplied by time
State that source e.m.f. is measured in volts
Define component potential difference as work done per unit charge
State resistance as potential difference divided by current
Apply resistance equals potential difference divided by current
Apply wire-resistance proportionalities for length and cross-sectional area

G2 Science (Physics) · Topic 10

Read the complete lesson from top to bottom first. Pause for its examples and independent questions, then use a short topic check to decide what to practise again.

Start topic

Before you begin

Build the idea in order

Charge
Current and direction
Potential difference
Resistance

Lessons

Electric Charge and Current

Charge interactions, current and direction, Q = It, e.m.f., potential difference, resistance and controlled wire comparisons.

Check your understanding

Electric charge and current topic check

Check the required topic capabilities and get focused practice for ideas that need another look.

What to remember

Unlike charges attract and like charges repel.
Conventional current opposes electron flow in metals.
Use Q = It with time in seconds.
Potential difference is work per unit charge.
Use R = V/I for matching circuit quantities.

Topic and syllabus information

Electric charge and current is Topic 10 in K223 / K224 Physics component · 2027.

The lesson stays within G2 depth and includes the explanations, examples and practice needed for this topic.

Reviewed 9 Aug 2026

Official K223 syllabus

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Course and syllabus information

Course: SEC G2 Science Physics component
Edition: SEC G2 Science Physics component 2027