Advertisements
Advertisements
प्रश्न
How much energy does a 100 W electric bulb transfer in 1 minute?
(a) 100 J
(b) 600 J
(c) 3600 J
(d) 6000 J
Advertisements
उत्तर
(d) 6000 J
Energy transferred, E = power x time = 100 W x 60 s = 6000 J
APPEARS IN
संबंधित प्रश्न
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
1 kWh = ________ J
Why is an electric light bulb not filled with air? Explain why argon or nitrogen is filled in an electric bulb.
Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220 V supply line?
(a) 500°C
(b) 1500°C
(c) 2500°C
(d) 4500°C
Name the S.I unit of electrical energy. How is it related to Wh?
An electric bulb is rated ‘100 W, 250 V’. What information does this convey?
The coil of an electric bulb takes 40 watts to start glowing. If more than 40 W are supplied, 60% of the extra power is converted into light and the remaining into heat. The bulb consumes 100 W at 220 V. Find the percentage drop in the light intensity at a point if the supply voltage changes from 220 V to 200 V.
The diagram below shows a magnetic kept just below the conductor AB which is kept in North South direction.

(i) In which direction will the needle deflect when the key is closed ?
(ii) Why is the deflection produced ?
(iii) What will be the change in the deflection if the magnetic needle is taken just above the conductor AB ?
(iv) Name one device which works on this principle.
Why is the heating element of an electric oven wound on a helix? State the reason.
An electric filament lamp is connected to a supply of voltage higher than the recommended value. Give reasons, why compared with a normal performance, the lamp emits a brighter light and its life is shortened.
‘The current rating of a fuse is 5A’. Comment on this statement.
Two lamps are rated 220V, 50W and the other rated 220V, 100W are connected in series with the mains of 220 V. Explain, why the 50W lamp glows more?
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?
How does earthing prevent electrical shock?
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate the energy supply in kWh to the three heaters in 5 hour.
An Electric bulb is marked 100 W, 230 V. What current does it take?
Find the cost of operating an electric toaster for two hours if it draws 8 A current on a 110 volt circuit. The cost of electrical energy is Rs. 2.50 per kWh.
A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?
`[ρ_(Cu) = 1.7 xx 10_(Ωm)^-8, ρ_(Al) = 2.7 xx 10^-8 Ωm]`
