Practical Electricity

What will happen when a 240 V, 2 kW electric heater is connected to a mains supply using a plug fitted with a 4 A fuse ?

• the fuse in the plug melt

• the heater works normally

• the heater runs at half power

• the heater burns out

A portable tape-recorder is rated at 12 W, 2 A. How many 1.5 V batteries are needed in the tape-recorder ?

• 2

• 4

• 6

• 8

An electric heater takes a current of 4 A from a 250 V supply when operating normally. How long would it take the heater to convert 400 000 J of electrical energy?

• 400 s

• 1 000 s

• 1 600 s

• 100 000 s

Electric energy produced by light a bulb with resistance of 6 ohm when it is passed by electric current for 60 second is 1440 J, the electric current flowing through the light bulb is ….

• 4 A

• 3 A

• 2 A

• 1 A

Given an AC of 750 watt, iron of 350 watt, a lamp of 60 watt, an electric stove of 500 watt. If the use is equal to 3 hours with voltage of 220 volt, the equipment using the most energy is ….

• AC

• Lamps

• Iron

• Electric stove

A circuit breaker in a house is set on a voltage of 220 V and flowing current is 2 A. The power of circuit breaker is ….

• 220 W

• 330 W

• 440 W

• 550 W

An electric stove has power of 550 W at a voltage of 110 V, then the fuse chosen is ....

• 15 A

• 13 A

• 10 A

• 5 A

A light bulb has a label of 100 W;220 V, then its electric resistance is ....

• 
• 
• 
• 

A lamp having a label of 220 V, 110 W is connected to a voltage source of 110 V. The power used by the lamp is ....

• 25 W

• 27.5 W

• 50 W

• 100 W

A devices works of 1500 joules for a minute. The power of the devices is .....

• 25 watts

• 40 watts

• 100 watts

• 1040 watts