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Miracle Learning Centre Physics Tuition Question on Practical Electricity. (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition)

Fig 11.1 shows a plug fitted with a 13 A fuse.

(i) Explain why a fuse is included the plug. [1] ……………………………………………………………………………..…………………………………………………………………………….. (ii)What is wrong with the way this plug has been wired and how should the mistake be rectified? [2] ……………………………………………………………………………..…………………………………………………………………………….. ……………………………………………………………………………..

Fig 11.2 shows a metal electric kettle which can be used to boil water. The power rating of the kettle is 0.5 kW.

Which part of the kettle should be connected to the earth pin of the plug? [1] ………..…………………………………………………………………………….

Water of mass 0.80 kg, at a temperature of 25°C is to be heated. Calculate the time taken for the water to be heated to a temperature of 90°C. [3] (Take specific heat capacity of water to be 4200 J/kg/°C)

State one assumption that you made in (ii). [1]

The cost of 1 kWh of electrical energy is 25 cents. How much will it cost to operate the heater for 45 minutes. [2]

Miracle Learning Centre Answer to Science Tuition Question on Practical Electricity. (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition) 1 (a)(i) When the current flowing in the live wire is higher than the fuse rating, it will melt and stop current flow and protect the appliance from overheating [A1] (ii) The fuse is connected to the neutral wire [A1]. The fuse should be connected to the live wire. [A1] (b)(i) Metal casing/body of the kettle. [A1] (ii)

(iii) No heat loss to surroundings [A1].

(iv)

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