Questions on Characteristic Curves - Filament Lamp
Q6.
(a) Sketch, on the axes below, the current–voltage (IV) characteristic for a filament lamp for currents up to its working power.
[2 marks]
(b)
(i) State what happens to the resistance of the filament lamp as the current increases.
[1 mark]
(ii) State and explain whether a filament lamp is an ohmic or non-ohmic conductor up to its working power.
[1 mark]
(c) Three identical filament lamps, P, Q and R are connected in the circuit as shown below:
The filament in lamp Q melts so that it no longer conducts. Explain why lamp P becomes brighter and lamp R becomes dimmer.
[2 marks]
(d) A filament lamp, X, is rated at 60 W 230 V.
Another type of lamp, Y, described as 'energy saving' has the same light intensity output but is rated at 11 W 230 V.
(i) Calculate the electrical energy converted by each lamp if both are on for 4 hours a day for a period of 30 days.
[2 marks]
(ii) Suggest why the two lamps can have different power ratings but have the same light intensity output.
[2 marks]
(Total 10 marks)
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