heat produced in a conductor of resistance 4.2ohm with 10A current is

@ gayathri 
I think the time must be given in the question , if not then u can directly apply the joules law of heating in that case 
which formula is 
H = I SQUARE R 
SO, BY CALCULATING 
H = 10 square * 4.2 
H= 100 * 4.2 
H= 420 JOULE . 
hope it clears your doubt 

all the best ...

heat produses many ways like sunheat is very product it can used elevators solar many types arein  our sun heat
 

We know that,H=I2RT

As we know it from JOULES LAW,

But T is not given,so,H=I2R

H=(10*10*4.2)

H=420JOULES/SEC

H=420/(4.2)=100CAL/SEC