Advertisements
Advertisements
Question
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?
Advertisements
Solution
The SI unit of electrical energy is joule.
The SI unit of electrical power is watt.
(i) Kilowatt-hour is the household unit of electrical energy. It is defined as the quantity of electrical energy consumed in 1 hour when the rate of consumption is 1000 watts, i.e. 1000 J/s.
(ii) A voltage of 220 volt is generally supplied to a house.
APPEARS IN
RELATED QUESTIONS
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
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?
An electric bulb is rated ‘100 W, 250 V’. What information does this convey?
Two lamps, one rated 220 V, 50 W and the other rated 220 V, 100 W, are connected in serieswith mains of 220 V. Explain why does the 50 W lamp consume more power
When a current I flows through a resistance R for time t, the electrical energy spent is given by:
(a) IRt (b) I²Rt (c) `IR^2t` (d) `I^2R ⁄t`
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 changes in energy occur in an electric bulb?
What would happen and why, to an electric bulb when it is connected across a supply of voltage (i) lower (ii) higher than its proper rating?
Why is the electric power from the generating station transmitted at high voltage?
