Chapter 18 | Electric Current, e.m.f. & p.d.

Electric Current, e.m.f. & Potential Difference

Follow charge through a metal, select safe meter ranges, compare direct and alternating current, and track energy transferred per coulomb around a complete circuit.

Cambridge IGCSE Physics
Core + Supplement

Investigation 1 — What makes a current?

Charge passing the point 12 C

Time interval 4 s

free electronsconventional current

Investigation 2 — Choose and connect an ammeter

Normal series-circuit current 0.42 A

Ammeter range

Investigation 3 — Compare d.c. and a.c.

Peak current 2.0 A

a.c. frequency 2 Hz

Investigation 4 — Follow energy per unit charge

Source e.m.f. 6.0 V

Charge moved 4 C

Component

Voltmeter type / range

Chapter 18 checkpoint — submit before seeing feedback

1. A charge of 24 C passes a point in 6.0 s. Calculate the current.

2. Which direction describes free-electron flow in the external circuit?

positive to negative negative to positive

3. An ammeter must normally be connected…

4. Which graph represents alternating current?

5. A source transfers 18 J while moving 3.0 C. Calculate its e.m.f.

6. Where is a voltmeter connected to measure the p.d. across a lamp?