Single Choice

An electric wire of length $$'l$$ and area of cross-section $$a$$ has a resistance $$R$$ ohm. Another wire of the same material having same length and area of cross section $$4a$$ has a resistance of

A$$4\ R$$
B$$R/4$$
Correct Answer
C$$R/16$$
D$$16\ R$$

Solution

we know $$R=\dfrac {\rho l}{a}$$
where a is the area and l is the length of wire
For first wire an $$R=\dfrac {\rho l}{4a}=\dfrac {R}{4}$$ for second wire.

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