Questions on Characteristic Curves - Filament Lamp

Q7. The sketch graph below shows the current–voltage (I–V) characteristics for a resistor and a filament lamp.

(a) Explain, in terms of electron motion, why the I–V characteristic for the filament lamp is a curve.

[4 marks]

(b) Determine the resistance of the resistor.

[1 mark]

(c) The resistor and the filament lamp are connected in series with a supply of variable emf and negligible internal resistance.

Determine the emf that produces a current of 0.18 A in the circuit.

[3 marks]

(d) The resistor and filament lamp are now connected in parallel.

Determine the resistance of the parallel combination when the emf of the supply is adjusted to be 4.0 V.

[3 marks]

(e) The resistance of the filament lamp at its working temperature is 14 Ω.

The filament has a length of 0.36 m and a diameter of 32 µm.

Calculate the resistivity of the metal that is used for the filament when the lamp is at its working temperature.

Give an appropriate unit for your answer.

[3 marks]
(Total 14 marks)