Question

Calculate the heat emitted by a bulb of 100 W in 1 min.
A. 100 J
B. 1000 J
C. 600 J
D. 6000 J

Answer 1

Hint: The amount of heat emitted by a device is equal to the amount of work done by that device. Power of a device can be defined as the rate at which that device does work. By calculating work done by the given bulb, we can get the amount of heat emitted by the bulb.
Formula used:
Power of device is the rate of doing work given as
$P = \dfrac{W}{t}$
where P is the power of the device, W represents the amount of work that the device is doing, t represents the duration of time for which the device does work.

Complete answer:
We are given a bulb whose power consumption is given as
$P = 100W$
The duration for which it is operated is given as
$t = 1\min = 60s$
Now, the work done by the bulb is equal to the product of its power and time for which it is operated. Therefore, we can write
$W = P \times t = 100 \times 60 = 6000J$
This is the amount of heat energy generated by the bulb

So, the correct answer is “Option B”.

Additional Information:
We can also define the power of a bulb and the work done by it in terms of the current flowing through the bulb. The power is given as
$P = {I^2}R = VI$
While the work done can be written as
$W = {I^2}Rt = VIt$
Thus, the work done and power of a device are directly related to the current flowing through the given device.

Note:
1. The student must convert the units of time into seconds before solving the problem.
2. It should be noted that the power of a device does not depend on the time for which it is operated. But the amount of work done or the amount of heat generated will depend directly on the time for which the bulb is operated.