Explain :
Why is the Tungsten used almost exclusively for filament of electric lamps?
Why are the conductors of electric heating devices such as bread - toasters and electric ions made of an alloy rather than a pure metal?
Answers
Answer:
1)Tungsten metal is used exclusively for making the filament of electric bulbs because it has a very high melting point.
Due to its high melting point, the tungsten filament can be kept white hot without melting away.
2)The conductors of electric heating devices such as bread toasters and electric irons are made of alloy because resistivity of an alloy is more than that of metals which produces large amount of heat.
In series circuits voltage is divided. Each component of a series circuit receives a small voltage so the amount of current decreases and the device becomes hot and does not work properly.
Hence, series arrangement is not used in domestic circuits.
Resistance (R) of a wire is inversely proportional to its area of cross-section (A), i.e. when area of cross section increases the resistance decreases or vice versa.
Copper and aluminum are good conductors of electricity also they have low resistivity.
So they are usually used for electricity transmission.
Answer:
(1) The temperature of the electric lamps is extremely high. Hence, tungsten is mainly used as the heating element of electric bulbs. Tungsten has very high melting point and very high resistivity so does not burn easily at a high temperature. ... So they are usually used for electricity transmission.
(2) The conductors of electric heating devices such as bread toasters and electric irons are made of alloy because resistivity of an alloy is more than that of metals which produces large amount of heat. ... So they are usually used for electricity transmission.