Experiment 4 — Build a Circuit

Topic: Physics · Classes 4–5 · Conductors, insulators and closed circuits

Aim: Make the bulb glow brightly .

Daily: Every switch in your home opens or closes a circuit exactly like this one. A torch is a cell, a bulb and a switch — nothing more. And the plastic around every wire is there to keep the current in, and you safe.

Question: A pencil lead (graphite) is placed in the gap. What happens?

Exp: Graphite is a non-metal that conducts electricity — unusual, and worth remembering.

Question: Why does an open switch stop the bulb glowing?

Exp: Current needs an unbroken loop.

Exp: Rubber does not let current pass.

Question: Two cells instead of one make the bulb…

Exp: More push (voltage) means more current.

Question: Copper wires are covered in plastic because…

Exp: The conductor carries current; the insulator contains it.