An electric iron rated 750 W is operated for 2 hours/day. How much energy is consumed by the electric iron for 30 days?
What determines the rate at which energy is delivered by a current?
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
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
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`
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.
A simple electric circuit has a 30 V battery and a resistor of 60 Ω. What will be the current in the circuit? The resistance of the connecting wires is negligible.
State two advantages of filling an inert gas in an evacuated electric filament lamp.
What do you understand by ‘earthing’? What are the advantages of earthing in a household electric circuit? Explain, how it is done?
State relative advantages and disadvantages of ring system of wiring over the tree system.
An electric heater is rated 220 V, 550 W. What does this statement mean?
At what voltage is the electric power generated at the generating station? Explain the transmission of this power to your house.
An electric kettle is rated 3kW, 250V. What should be the current capacity of the fuse with it?
Find the heat produced in joules when a current of 10 amperes flows through a connecting wire of resistance 2 × 10-2 ohms and heating element of resistance 250 ohms for 2 seconds.
Two bulbs are rated: bulb A 100W, 120 V bulb B 10W, 120 V. If both are connected across a 120V supply, which bulb will consume more energy, When in series? Also calculate the current through each bulb in above cases.
A cooler of 1500 W, 200 volts and a fan of 500 W, 200 volts are to be used from a household supply. The rating of fuse to be used is:
What is the commercial unit of electrical energy?
A family uses 8 kW of power. Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
Using a long extension cord in which each conductor has a resistance of 8Ω, a bulb marked as '100 W, 200 V' is connected to a 220 V dc supply of negligible internal resistance as shown in the figure. The power delivered to the bulb is ______ W.
A fuse is rated 5 A. Can it be used with a geyser rated 1540 W, 220 V Write Yes or No. Give supporting calculations to justify your answer.
