Advertisements
Advertisements
प्रश्न
An electric kettle for use on a 230 V supply is rated 3000 W. For safe working, the cable connected to it should be able to carry at least:
(a) 2 A
(b) 5 A
(c) 10 A
(d) 15 A
Advertisements
उत्तर
(d) 15 A
Current drawn by the kettle, I = `I=P/V=3000/230=13A`
So the cable should be able to carry more current than this and hence the answer is 15 A
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?
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
At what frequency is AC supplied to residential houses?
What is consumed using different electrical appliances, for which electricity bills are paid?
Name two safety devices which are connected to the live wire of a household electric circuit
When an electric lamp is connected to 12 V battery, it draws a current of 0.5 A. The power of the lamp is:
(a) 0.5 W
(b) 6 W
(c) 12 W
(d) 24 W
Name two gases which are filled in filament type electric light bulbs.
List the names of three electrical gadgets used in your house. Write their power, voltage ratingand approximate time for which each one is used in a day. Hence find the electrical energyconsumed by each in a day.
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 toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.
Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.

The diagram above shows a circuit with the key k open. Calculate :
(i) the resistance of the circuit when the key k is open.
(ii) the current drawn from the cell when the key k is open.
(iii) the resistance of the circuit when the key k is closed.
(iv) the current drawn from the cell when the key k is closed.
What is the current in the circuit shown (Fig. )

Express watt hour and kilowatt hour in joule.
Which cable, one rated 15A and the other rated 5A will be thicker? Give a reason.
An electric heater is rated 220 V, 550 W. Calculate the electrical energy consumed in 3 hours?
An Electric bulb is marked 100 W, 230 V. What current does it take?
A house is provided with 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80 W, and one heater of 1.0 kW. Each day bulbs are used for 4h, fans for lOh, and heater for 2h. The voltage of mains is 220 V. Calculate:
(i) Maximum power of the circuit in the house,
(ii) maximum current capacity of the main fuse in the house,
(iii) the electrical energy consumed in a week,
(iv) cost of electricity consumed at 1.25 Rs. per kWh.
What is the commercial unit of electrical energy? Represent it in terms of joules.
A student wants to use an electric heater, an electric bulb and an electric fan simultaneously.
How should these gadgets be connected with the mains? Justify your answer giving three reasons.
