# A constant voltage is applied to the two ends of a uniform metallic wire. Some heat is produced in it. The heat developed is doubled if

$\begin {array} {1 1} (A)\;Both\: the\: length\: and\: the\: radius\: were\: halved \\ (B)\;Both\: the\: length \: and \: the \: radius\: were \: doubled \\ (C)\;The\: radius \: is \: doubled \\ (D)\;The\: length\: is\: doubled \end {array}$

When both length and radius are doubled, the resistance is halved
and hence power dissipation is doubled as the power is inversely proportional to resistance
Ans : (B)

edited Sep 10, 2014