D.C. circuits

Circuit symbols, series and parallel rules, effective resistance and whole-circuit calculations.

Learning goals

Recognise and interpret circuit symbols for cells, batteries, switches, lamps, LEDs, resistors, fuses, ammeters and voltmeters
Draw circuit diagrams with cells, batteries, switches, lamps, LEDs, fixed and variable resistors, fuses, ammeters and voltmeters
Apply the same-current rule in series circuits
Apply the potential-difference sum in series circuits
Apply current conservation at parallel junctions
Apply equal potential difference across parallel branches
Calculate effective resistance in series
Calculate effective resistance in parallel
Solve whole-circuit problems using consistent quantities

G3 Science (Physics) · Topic 13

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.

Circuit symbols, series and parallel rules, effective resistance and whole-circuit calculations.

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

Calculate source current and component p.d. in mixed resistor networks, correct inconsistent measurements, and account for branch currents.

Use standard symbols, connect an ammeter in series and connect a voltmeter in parallel.
In series, current is the same everywhere and component potential differences add to the supply p.d.
In parallel, every branch has the same p.d. and branch currents add to the source current.
Series resistances add directly; parallel resistances add through their reciprocals.
For R = V/I, make sure the potential difference and current refer to the same component or section.

D.C. circuits is Topic 13 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