1.

If a wire of resistance R is melted and recasted tohalf of its length, then the new resistance of thewire will bea) R/4 b) R/2 (c) R (d) 2R

Answer»

Resistance of the wire before melting=R

Original length =l

Original area =A

WKT

R=ρl/A

New resistance R'=ρl/'A'

=ρl/2/2A

1/4ρl/A

= 1/4R

R' = R/4

why area is double?



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