Question

Questions 96. An electric bulb is marked 250 W - 200 V. What information does it convey? How many joules of energy is consumed by this bulb in one hour? How long will it take for the bulb to consume 1 kWh?
[Ans 900000 J, 4 h]

Answer 1

Dear Student,
250W is the power rating of the bulb which means that it will consume 250 Joules of energy every second and work normally up to a maximum voltage of 200V.

$$\begin{gathered} \mathrm{P}=250\mathrm{W} \\ \mathrm{V}=230\mathrm{V} \\ \left(1\right)\mathrm{Energy}\mathrm{consume}\mathrm{in}\mathrm{one}\mathrm{hour}=\mathrm{P}\times \mathrm{t} \\ \mathrm{Energy}\mathrm{consume}\mathrm{in}\mathrm{one}\mathrm{hour}=250\times 60\times 60=9\times {10}^5\mathrm{J} \\ \left(2\right)1\mathrm{kWh}=250\times \mathrm{t} \\ 1000\mathrm{Wh}=250\mathrm{t} \\ \mathrm{t}=\frac{1000}{250}=4\mathrm{h} \end{gathered}$$
Regards