# Electric Power

## Trending Questions

**Q.**

Define 1 watt of power.

**Q.**

An electric heater of power 3 kW is used for 10 h.How much energy does it consume? Express your answer in (i) kWh, (ii) joule.

**Q.**

An electric heater of resistance 8 Ω draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater.

**Q.**Question 16

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

**Q.**Define 1 volt.

**Q.**

What are the functions of a Transformer?

**Q.**

If an electric iron of $1200\mathrm{W}$ is used for $30$ minutes everyday, find electric energy consumed in the month of April.

**Q.**

Find the total cost of consumption of electrical energy in the following case, if electrical energy costs Rs. 2 per unit (kWhr)

1) 8 bulbs of 100 W each for 20 hrs

2) 500 W heater for 10 hours

**Q.**Which is eco friendly? Wearing an extra sweater or using a heating device on cold days?

**Q.**

Define 1 kilowatt-hour.

**Q.**Question 25

What is the commercial unit of electrical energy? Represent it in terms of joules.

**Q.**

Explain why coils of electric toasters and electric irons made of an alloy rather than a pure metal?

**Q.**

Is power directly proportional to the resistance?

**Q.**

What measures would you take to conserve electricity in your house?

**Q.**Two bulbs marked 200 watt-250 volts and 100 watt-250 volts are joined in series to 250 volts supply. Power consumed in circuit is:

100 watt

67 watt

33 watt

300 watt

**Q.**

$1$ unit is equal to?

**Q.**

A 100W electric bulb is connected to 220V main power supply. Calculate the strength of electric currect passing through the bulb. If the same bulb is taken to USA where the main power supply is 110V, how much electric current will pass through the bulb when connected to mains?

**Q.**

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

**Q.**

Name the commercial unit of electric energy.

**Q.**

Define electric potential at a point. What is its SI unit?

**Q.**

Several electric bulbs designed to be used on a $220V$ electric supply line, are rated $10W$. How many lamps can be connected in parallel with each other across the two wires of $220V$ line if the maximum allowable current is $5A$?

**Q.**

Two bulbs have ratings 100 W, 220 V and 60 W, 220 V respectively. Which one has a greater resistance?

**Q.**Question 18

Unit of electric power may also be expressed as

(a) volt ampere

(b) kilowatt hour

(c) watt second

(d) joule second

**Q.**

Calculate the amount of charge that would flow in 2 hours through an element of an electric bulb carrying a current of 0.25A

Ammeter

Voltmeter

manometer

water meter

**Q.**

An electric heater is rated at 2 kW. Electrical energy costs Rs 4 per kWh. What is the cost of using the heater for 3 hours ?

(a) Rs 12

(b) Rs 24

(c) Rs 36

(d) Rs 48

**Q.**

An electric motor of power 2 kW is to be operated at mains of 220 V. Find the current rating of the fuse to be connected to the motor.

10 A

8 A

5 A

2 A

**Q.**

A bulb of power 40 W is used for 12.5 hrs each day for 30 days. Calculate the electrical energy consumed.

**Q.**An electric refrigerator rated 500W operates 24 hours/day. What is the cost of the energy to operate it for 20 days at rupees 2.00 per kWh.

**Q.**

An electric room heater is rated at 2kW . Calculate the cost of using it for 2 hours daily in the month of September for 30 days if each unit costs Rs 4

**Q.**

Is one joule per second equivalent to one watt?