Current Electricity

Syllabus tag: KCSE | Physics | Form 3 | Topic 25 Current Electricity

Lesson objectives

By the end of this topic, you should be able to:

• Define current, potential difference and resistance and state their units.
• State and apply Ohm's law and interpret I-V graphs.
• Calculate resistors in series and in parallel.
• Explain e.m.f., internal resistance and the factors affecting resistance.

Summary

Current is the rate of flow of charge, in amperes. Potential difference is the work done per unit charge, in volts. Resistance is V ÷ I, in ohms. Ohm's law states that current is proportional to potential difference at constant temperature. Resistors add in series but combine reciprocally in parallel.