(a) State Joule’s law of heating(b) An alloy of nickel and chromium

1.	(a) State Joule’s law of heating(b) An alloy of nickel and chromium is used as the heating element. Why? (c) How does a fuse wire protect electrical appliances?
Answer» (a) Joule’s law of heating states that the heat produced in any resistor is: 1. directly proportional to the square of the current passing through the resistor. 2. directly proportional to the resistance of the resistor. 3. directly proportional to the time for which the current is passing through the resistor. (b) Because, 1. It has high resistivity, 2. It has a high melting point, 3. It is not easily oxidized. (c) When a large current passes through the circuit, the fuse wire melts due to Joule’s heating effect and hence the circuit gets disconnected. Therefore, the circuit and the electric appliances are saved from any damage.

(a) State Joule’s law of heating(b) An alloy of nickel and chromium is used as the heating element. Why? (c) How does a fuse wire protect electrical appliances?

Answer»

(a) Joule’s law of heating states that the heat produced in any resistor is:

1. directly proportional to the square of the current passing through the resistor.

2. directly proportional to the resistance of the resistor.

3. directly proportional to the time for which the current is passing through the resistor.

(b) Because,

1. It has high resistivity,

2. It has a high melting point,

3. It is not easily oxidized.

(c) When a large current passes through the circuit, the fuse wire melts due to Joule’s heating effect and hence the circuit gets disconnected. Therefore, the circuit and the electric appliances are saved from any damage.

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