Advertisements
Advertisements
Question
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Advertisements
Solution
Energy consumed by an electrical appliance is given by the expression, H = Pt
Where,
Energy consumed by a TV set of power p = 250 W in 1 h = 250
Time, t = 1 hr = 3600 sec
H = P × t
= 250 × 3600
= 900000
H = 900000 J
Energy consumed by a toaster of power 1200 W
Time, t = 10 minutes = 600 sec
H = P × t
= 1200 × 600
= 720000
H = 720000 J
Therefore, the energy consumed by a 250 W TV set in 1 hour is more than the energy consumed by a toaster of 1200 W in 10 minutes.
APPEARS IN
RELATED QUESTIONS
Write an expression for the electrical power spent in flow of current through a conductor in terms of
(a) Resistance and potential difference, (b) current and resistance.
Name the physical quality which is measured in
(i) Kw (ii) kWh
Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances
An electric kettle is rated 2.5 kW, 250 V. Find the cost of running the kettle for two hours at Rs. 5.40 per unit.
An electric bulb marked 220 V, 100 W will get fused if it is made to consume 150 W or more. What voltage fluctuation will the bulb withstand?
Name the physical quantity which is measured in kW.
Why is heating coil wound in the form of a helix in electric stove?
Mention three uses of the carbon arc.
Why is the heating element of an electric oven wound on a helix? State the reason.
What changes in energy occur in an electric bulb?
A device is used to transform 12 V a.c. to 200 V a.c. What is the name of this device? Name the principle on which it works.
Give two precautious that you would take while putting off an electric switch.
An electric kettle is rated 3kW, 250V. What should be the current capacity of the fuse with it?
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the resistance of its filament while glowing.
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 ______.
What is the meaning of electric power of an electrical device? Write its SI unit.
