Questions on Electric Circuits
Q11. A pupil connects a battery, an electric bell and some wires. Her circuit is shown in the diagram.
(a) Why does the bell not ring?
There is not a complete circuit. The gap in the wiring means a current will not flow through the bell. 
1 mark
She adds a shiny steel pin as shown in the diagram below.
(b) Why does the bell ring now?
The steel pin is a conductor. Good conductors have low resistance to current. It completes the circuit allowing current to flow though the bell.
1 mark
(c) She replaces the shiny steel pin with a wooden matchstick. Why does the bell not ring?
The wooden matchstick is an insulator. Insulators have very high resistance. It prevents current from flowing though the bell.
1 mark
(d) She replaces the matchstick with a very rusty steel pin. The bell does not ring. Suggest why.
The rust is an insulator. It prevents current from flowing though the bell.
1 mark
Maximum 4 marks
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