Question

A copper wire of resistivity 1.6× 10*-8 ohm metre has a cross sectional area 20× 10 raise to minus 4 cm square calculate the length of the wire required to make 10 ohm coil​

Answer 1

★ For a copper wire -

Given :-

$\sf{Resistivity \: (p) = 1.6\times 10^{-8} \: ohm \: m}$

$\sf{Cross \: Section \: Area \: (A) = 20\times 10^{-4} \: cm^{2} = 20\times 10^{-8} \: m^{2}}$

$\sf{Resistance \: (R) = 10 \: ohm}$

To Find :-

$\sf{required \: length \: of \: the \: copper \: wire = ? \: }$

Using Formula :-

$\sf{Resistance \: (R) =p\dfrac{L}{A}}$

Solution :-

By USING ABOVE FORMULA -

$\sf{L =\dfrac{RA}{p}}$

$\sf{L =\dfrac{10\times 20\times 10^{-8}}{1.6\times 10^{-8}}}$

$\sf{L =\dfrac{200}{1.6}}$

$\sf{L =\dfrac{25}{0.2}}$

$\sf{L =\dfrac{250}{2}}$

$\sf{L = 125 \: metre}$

We Got -

$\sf{We \: require \: 125 \: metre \: copper \: wire \: to \: make \: 10 \: ohm \: coil .}$