Lakhmir Singh and Manjit Kaur Solutions for Chapter: Electricity, Exercise 34: Multiple Choice Questions (MCQs)

An electric heater is rated at $2 \mathrm{kW}$. Electrical energy costs $₹4 per \mathrm{kWh}$. What is the cost of using the heater for $3 \mathrm{hours}$?

The SI unit of energy is:

The commercial unit of energy is:

How much energy does a $100 \mathrm{W}$ electric bulb transfer in $1 \text{minute}$?

An electric kettle for use on a $230 \mathrm{V}$ supply is rated at $3000 \mathrm{W}$. For safe working, the cable connected to it should be able to carry at least:

How many joules of electrical energy is transferred per second by a $6 \mathrm{V}, 0.5 \mathrm{A}$ lamp?

At a given time, a house is supplied with $100 \mathrm{A}$ at $220 \mathrm{V}$. How many $75 \mathrm{W}$, $220 \mathrm{V}$ light bulbs could be switched on in the house at the same time (if they are all connected in parallel)?

If the potential difference between the ends of a fixed resistor is halved, the electric power will become: