Lesson Plan

• Describe how fuses protect circuits and the principle of operation.
• Explain the operation of thermal and magnetic trip switches.
• Calculate appropriate fuse ratings and circuit‑breaker settings for a given load.
• Compare advantages and limitations of fuses versus trip switches.
• Apply safety criteria to select the correct protective device for household or simple industrial circuits.

• Projector and screen
• Whiteboard and markers
• Printed handouts with fuse and breaker diagrams
• Sample cartridge fuse and miniature circuit‑breaker
• Calculator
• Worksheet with practice problems
• Safety goggles (optional)

Begin with a brief news clip of an electrical fire caused by an overloaded circuit to capture interest. Ask students to recall how current, resistance and power are related, linking this to why over‑current is dangerous. Explain that by the end of the lesson they will be able to select and justify the correct protective device for a given circuit.

1. Do‑now (5'): Quick calculation of current from power (P=VI) on the board.
2. Mini‑lecture (10'): Explain fuse construction, operation and types, using the projector diagram.
3. Hands‑on demo (8'): Show a fuse blowing in a simple circuit; discuss observations.
4. Mini‑lecture (10'): Introduce trip switches, thermal vs magnetic mechanisms, and setting guidelines.
5. Guided practice (12'): Work through the lighting‑circuit example, students calculate fuse and breaker ratings.
6. Independent worksheet (10'): Students complete three practice questions, teacher circulates for formative feedback.
7. Check for understanding (5'): Quick quiz via Kahoot or show‑of‑hands on key concepts.

Summarise the key steps for selecting protective devices and the differences between fuses and trip switches. Ask each student to write an exit ticket stating one situation where a fuse is preferred and one where a circuit‑breaker is preferred. For homework, assign a set of real‑world scenarios requiring students to calculate and justify appropriate ratings.