Electric charge and current

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

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

G3 Science (Physics) · Topic 12

Begin with the complete topic lesson. Then try a short check, use the feedback to review one idea and come back later for another attempt.

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

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

Unlike charges attract and like charges repel; charge is measured in coulombs.
Current is charge flow per second. Conventional current and electron flow in a metal have opposite directions.
Use Q = It with time in seconds.
Potential difference is work done per unit charge through a component; e.m.f. and p.d. are measured in volts.
Use R = V/I. For the same material and temperature, resistance rises with length and falls with cross-sectional area.

Electric charge and current is Topic 12 in K326 / K327 Physics component · 2027.

The lesson and questions stay at the depth required for this course.

Reviewed 9 Aug 2026

Course and syllabus information