English Medium Class 10 - CBSE Question Bank Solutions

State two factors on which the electrical energy consumed by an electrical appliance depends.

Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?

An electric bulb is rated at 220 V, 100 W. What is its resistance?

What is the SI unit of (i) electric energy, and (ii) electric power?

Name the quantity whose unit is (i) kilowatt, and (ii) kilowatt-hour.

Which quantity has the unit of watt?

What is the meaning of the symbol kWh? Which quantity does it represent?

An electric lamp is labelled 12 V, 36 W. This indicates that it should be used with a 1 V supply. What other information does the label provide?

Define watt. Write down an equation linking watts, volts and amperes.

Define watt-hour. How many joules are equal to 1 watt-hour?

An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.

In a house two 60 W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours everyday. Calculate the electric consumed in 30 days.

A bulb is rated as 250 V; 0.4 A. Find its : (i) power, and (ii) resistance.

An electric motor takes 5 amperes current form a 220 volt supply line. Calculate the power of the motor and electric energy consumed by it in 2 hours.

Which uses more energy: a 250 W TV set in 1 hour or a 1200 W toaster in 10 minutes?

An electric kettle connected to the 230 V mains supply draws a current of 10 A. Calculate:

(a) the power of the kettle.
(b) the energy transferred in 1 minute.

A 2 kWh heater, a 200 W TV and three 100 W lamps are all switched on from 6 p.m. to 10 p.m. What is the total cost at Rs 5.50 per kWh?

What is the maximum power in kilowatts of the appliance that can be connected safely to a 13 A ; 230 V mains socket?

An electric fan runs from the 230 V mains. The current flowing through it is 0.4 A. At what rate is electrical energy transferred by the fan?