Advertisements
Advertisements
Question
State two advantages of filling an inert gas in an evacuated electric filament lamp.
Advertisements
Solution
(i) The inert gas is filled at very low pressure to prevent oxidation as well as evaporation and thus increases its life.
(ii) While bulb is working, a convection current is set-up within it which carries the spurting particles of tungsten upward towards the cap and hence the blackening of the lower part (transparent portion) of the bulb is avoided.
RELATED QUESTIONS
An electric bulb is rated at 220 V, 100 W. What is its resistance?
What is meant by "electric power"?
Write an expression for the electrical power spent in flow of current through a conductor in terms of
(a) Resistance and potential difference, (b) current and resistance.
Name the physical quality which is measured in
(i) Kw (ii) kWh
Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.
Fig . shows the essent ial features of a battery operated bell. The hammer strikes the gong when the swi tch is closed . State and explain the effect of using the following material successively to form the core.
(a) Plastic
(b) Steel
(c) Copper
Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance.
What is the energy conversion when an electric current passes through a metallic wire?
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.
What is the commercial unit of electrical energy?
