If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be

Q: If a wire of resistance $R$ is melted and recasted to half of its length, then the new resistance of the wire will be

a (a) $R \propto {l^2} \Rightarrow \frac{{{R_1}}}{{{R_2}}} = {\left( {\frac{{{l_1}}}{{{l_2}}}} \right)^2}$$ \Rightarrow \,\frac{R}{{{R_2}}} = {\left( {\frac{l}{{l/2}}} \right)^2} = 4 \Rightarrow {R_2} = \frac{R}{4}$.

SECTION - A [PHYSICS - MCQ]

GSEB - English Medium

If a wire of resistance $R$ is melted and recasted to half of its length, then the new resistance of the wire will be

A$R/4$
B$R/2$
C$R$
D$2R$

Easy

STD 11 Science
NEET
STD 12 - 3. current electricity
Physics

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