Heating Effect of an Electric Current
Electricity · Heating Effect and Electrical Energy
Syllabus tag: KCSE | Physics | Form 3 | Topic 28 Heating Effect of an Electric Current
Lesson objectives
By the end of this topic, you should be able to:
- Explain the heating effect of a current and the factors affecting it.
- Apply the formulae for electrical energy and power.
- Calculate the cost of electrical energy in kilowatt hours.
- Describe domestic wiring, fuses, earthing and electrical safety.
Summary
A current passing through a resistance produces heat, given by Q = I²Rt. Electrical power is P = VI = I²R = V² ÷ R. Energy is sold in kilowatt hours, where one kWh is the energy used by a 1 kW appliance in 1 hour. Safety depends on fuses, earthing and correct wiring.