The resistance of the copper wire of length in meters and area of cross-section m2 is given by the formula
\( R=p\frac{t}{A}\)
The area of cross-section of the wire can be calculated as follows
\( A=n(\frac{Diameter}{2})^2\)
Substituting the values in the formula, we get
\(l = \frac{RA}{P}=\frac{10\,\times\,3.14\,\times(\frac{0.0005^2}{2})}{(1.6\,\times\,10^{-8})}=\frac{10\,\times\,3.14\,\times\,25}{4\,\times\,1.6}=122.72\,m\)
If the diameter of the wire is doubled, then the new diameter will be 1 mm or 0.001 m
Therefore, the resistance can be calculated as follows:
\( R= p\frac{l}{A}=1.6\,\times\,10^{-8}\times\frac{122.72\,m}{m(\frac{0.001}{2})^2}=250.2\,\times10^{-2}=2.5\,\Omega\)
The length of the wire is 122.72 m and the new resistance is 2.5 Ω.
Answered by Shivani Kumari | 1 year agoExplain the following.
a. Why is the tungsten used almost exclusively for filament of electric lamps?
b. Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
c. Why is the series arrangement not used for domestic circuits?
d. How does the resistance of a wire vary with its area of cross-section?
e. Why copper and aluminum wires are usually employed for electricity transmission?
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