A small generator is labelled as having an output of 2 kW, 230 V a.c. (at constant frequency). It is used to provide emergency lighting for a large building in the event of a breakdown of the mains supply. The circuit is shown below.

There are 30 light fittings on the circuit, each with a 230 V, 28 W halogen lamp.

a. Calculate the maximum current which the generator is designed to supply.

b. i. Calculate the power needed when all the lamps are turned on at the same time.

ii. Explain why this generator is suitable for supplying the power required but would not be suitable if all the lamps were exchanged for 100 W lamps.

c. Write down two reasons why all the lamps are connected in parallel rather than in series. In each answer, you should refer to both types of circuit.

d. Calculate the resistance of the filament of each 28 W lamp.

e. The figure below shows the current output of the generator when it is supplying all 30 of the 28 W lamps.

i. Calculate the frequency of the supply from the generator.

ii. Copy the diagram and sketch another graph to show the approximate current output of the generator when 15 lamps are removed from their fittings.

Transcribed Image Text:

generator output 2 kW/230 V a.c La 35