Q17 of 330 Page 66

A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it ?

Here Resistance of the coil(R) = 200 ohms, Current (I) = 2.5 amp, time(t) = 1 sec

We know that according to Joule's law of heating

H = I²RT

H = (2.5)²×200×1

H = 1250 J/s

Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.

When a current of 4.0 A passes through a certain resistor for 10 minutes, 2.88 x 10⁴ J of heat are produced. Calculate:

(a) the power of the resistor.

(b) the voltage across the resistor.

An electric heater of resistance 8 Ω takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater.

A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.