Find the heat produced in joule if a current of 0.1 A is passed through a coil of resistance 50 ` Omega` for two minutes. Keeping other conditions the same if the length of the wire is reduced to `1/4` th the original length ( by cutting the wire), what will be the heat produced ?

Explanation

Data : I = 0.1 A , R = 50 `Omega` , t= 2 minutes = ` 2 xx 60 ` s = 120 s, H = ?
H = ` I^(2) Rt = ( 0.1 A)^(2) xx 50 Omega xx 120 s = 0.01 xx 50 xx 120 J = 60 J`
Heat produced = 60 Joules.
In the second case, the resistance of the wire will be `( 50 Omega)/4` . Hence, the heat produced = `( 60 J )/4 = 15 J`
[ Note : There is no change in I and t. ]