Advertisements
Advertisements
Question
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
Advertisements
Solution
(d) watt
Watt is the unit of electric power.
APPEARS IN
RELATED QUESTIONS
Name the quantity whose unit is (i) kilowatt, and (ii) kilowatt-hour.
Which of the following is likely to be the correct wattage for an electric iron used in our homes?
(a) 60 W
(b) 250 W
(c) 850 W
(d) 2000 W
An electric bulb is rated at 220 V, 100 W. (a) what is its resistance? (b) what safe current can be passed through it?
What is the current in the circuit shown (Fig. )
State the S.I. units of electrical power and electrical energy.
(i) Define the household unit of electricity.
(ii) What is the voltage of the electricity that is generally supplied to a house?
Two resistors A and B of 4 Ω and 6 Ω, respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate the power dissipated in each resistor.
Point out two main disadvantages of ‘Tree System’.
State the position of heating element with respect to principal focus of concave reflector and give reason for choosing this position.
Household wiring for lamp connections can either be done in parallel or in series.Which one would you prefer? Give a reason for your answer.
Name a metal that is used as an electron emitter. Give one reason for using this metal.
State relative advantages and disadvantages of ring system of wiring over the tree system.
At what voltage is the electric power generated at the generating station? Explain the transmission of this power to your house.
How can electric energy consumed by an electric appliance be calculated in kilowatt hour (kWh)?
Establish the relation that heat produced in a metallic conductor due to the flow of current is V2t/R joules, where V is the potential difference across the ends of the conductor, R its resistance and t is the time in second for which current flows.
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the resistance of its filament while glowing.
The resistance of filament of an electric heater is 500 Ω It is operated at 200V for 1 hour daily. Calculate the current drawn by the heater and the energy consumed in kWh, by the heater in a month of 30 days.
The following table gives the electrical appliances used, their power and the average time for which they are used each day in a home. Estimate the monthly electricity bill if the rate is 60 paise per unit.
| Sr.no. | Name | Nos. | Power rating | Time/day |
| 1 | Bulb | 4 | 100 W | 7.5 hr |
| 2 | Fans | 2 | 50 W | 10 hr |
| 3 | T.V. | 1 | 100 W | 2 hr |
| 4 | Iron | 1 | 500 W | 1 hr |
| 5 | Electric stove | 1 | 750 W | 2 hr |
Unit of electric power may also be expressed as:
The unit of e.m.f. of a cell is ____________.
If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.
