Name The Factors On Which The Heat Produced In A Wire Depends When Current Is Passed In It, And State How Does It Depend On Those Factors.

Question

Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on those factors.

Solution

When a current of I (in ampere) flows through a resistor of resistance R (in ohm) for time t (in second), then from Joule’s law of heating we can write that, the amount of heat produced in a resistor, H = I²Rt. From the above formula, it can be said that, the amount of heat produced in a resistor is, (i)directly proportional to the square of current(H proportional I²) (ii)directly proportional to the resistance of the resistor (H proportional R) (iii)directly proportional to the time for which the current flows through the resistor (H proportional t)

Q- A 60W electric lamp connected in series with a room heater is further connected across the mains. If 60 W lamp is now replaced by a 100W lamp, will the heat produced by the heater be smaller, remain the same or be larger and why?

Chapter: Current Electricity

Question