Advertisements
Advertisements
Question
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.
Advertisements
Solution
The lamp will have the filament of a particular resistance. If it is connected to a supply of higher voltage, the heat energy produced in it will be more (since H = V2t/R), i.e., the filament will get more heated so it will glow more and the lamp will emit a brighter light. On the other hand, due to Excess heating, the filament may vaporize and so its life may shorten.
APPEARS IN
RELATED QUESTIONS
Define Electric power.
Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?
An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.
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
An electric current is passed through a metallic wire. The wire gets heated up. Give the reason. Is it possible to melt the wire by passing a heavy current?
Mention three uses of the carbon arc.
Why is a concave reflector placed behind the heating element in a room heater.
Name a metal that is used as an electron emitter. Give one reason for using this metal.
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?
