Explain the following questions
(i) Why is tungsten used almost ex
filament of electric lamps? CBS
(in) Why are the conductors of elect
devices such as bread toasters an
irons made of alloys rather th
metals?
(iii) Why is the series arrangement not
domestic circuits?
(iv) How does the resistance of a wire va
its area of cross-section?
(V) Why are copper and aluminium wire
employed for electricity transmission
ment not for user
minium wires usually
Answers
Answer:
1)tungsten is an alloy which has a very high melting point and very high resistivity so it does not burn or melt easily at high temperature
2)the conductors of electric heating devices such as bread toaster and electric irons are made of alloy because the resistivity of an alloy is more than that of metals which produce large amount of heat
3)in series circuit voltage is divided each component of a series circuit receives a small voltage so the amount of current decreases on the device become hard does not work properly hence the series arrangement not used in domestic circuits
4)resistance of a wire is inversely proportional to its area of cross section that is when area of cross section increases the resistance decreases or vice versa
5)copper and Aluminium are good conductors of electricity also they have low resistivity so they are usually used for electricity transmission