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प्रश्न
Explain why, filament type electric bulbs are not power efficient.
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उत्तर
Filament type of electric bulbs are not power efficient because a lot of power gets wasted as heat.
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संबंधित प्रश्न
The commercial unit of energy is :
(a) watt
(b) watt-hour
(c) kilowatt-hour
(d) kilo-joule
State whether an electric heater will consume more electrical energy or less electrical energy per second when the length of its heating element is reduced. Give reasons for your answer.
An electric bulb is rated ‘100 W, 250 V’. What information does this convey?
Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.
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?
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.
A coil of copper wire is connected to a galvanometer. What would happen if a bar magnet is:
(i) Pushed into the coil with its north pole entering first?
(ii) Held at rest inside the coil?
(iii) Pulled out again?
State the position of heating element with respect to principal focus of concave reflector and give reason for choosing this position.
Why does not the heating coil produce any visible light? in an electric stove.
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?
An electric heater is rated 220 V, 550 W. Electrical energy is also measured in kWh. What do you understand by a kilo-watt-hour?
How does earthing prevent electrical shock?
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
State other bigger units of electric power and express them in watt.
I ampere of current is passed through a resistor of resistance R ohm for time t second. Obtain expression for
(i) the electrical energy, and
(ii) the electrical power spent.
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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.
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