Question

1A heating element in an electric heater consists of a coil of wire.The heating element transfers a power of 1.00 kW when connected directly to a mains supply of 230 V. Show that the resistance of the element is approximately 53 2. The element is made from wire that has a radius of 0.137 mm and a resistivity of 4.9 × 1072 m. Calculate the length of wire needed for the element. The electric heater contains two elements, each of resistance 53 ohms There is also a 230 V lamp to show when the heater is working. The power transferred by the lamp is negligible. The resistivity of the wire does not vary with temperature.

Draw circuit diagrams to show how the components can be connected to transfer: • the maximum possible power using both elements• the minimum possible power using both elements.State, for each circuit, the total power transferred by the heater.

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