yes mr lonely's sentence is convincing to me...that we cannot generalise an eqn by just seeing a piece of wire.........thaks dude i just happened to get a wrong result (did already know it was wrong)when i was playing with the equation.....just wanted to analyse the faults........ ...............definitely radius does not increase with the increament in L good question by bidhan abt P=I2R and P=v2/R i appreciate everybody'd comments...........