Question

explain the following questions..

1.why is tungsten used almost exclusively for filament of electric lamps .
2.why are the conductors of electric heating devices such as bread toaster and electric irons made of alloy rather than pure metals .
3.why are Copper and Aluminium wires usually employed for Electricity Transmission .
4.how does the resistance of a wire vary with its area of cross section .

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Answer 1

1, Because tungsten has very high melting point , so could not burn at high temperature.

2,Because alloys do not oxidise readily and have higher resistivity.

3,Because these wires are good conductors of electricity and are available at cheap rates also.

4,Because resistance of a conductor is inversely proportional to its area of cross section.

Answer 2

Hey dear user ur answer------->

1.tungsten has high melting point .it does not melt at high temperature .it retains as much of heat generated ,so that it become very hot and emits light .that is the reason why tungsten is used as filament of electric lamps .

2.conductors of electric heating devices are made of alone because alloys do not oxidise readily at high temperature unlike metals. also alloys have a greater resistivity as compared to their constituent pure metal .

3.Copper and Aluminium wires are used for transmission of electricity because they have low resistivity .
so they conduct the electric current without having heat losses. also, they are quite cost effective as compared to Silver .


4. resistance is inversally proportional to the area of cross section of the wire .thus if the wire is thick ,then resistance is less . if the wire is thin then resistance is large .



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