# Electric power = I2*R= (0)2*infinity = can be any thing for open circuit?

1. Nov 5, 2014

### leojun

In an open circuit resistance is infinity and therefore current is zero.(voltage 220V)
power=iv=0*220=0 watt
power=I2*R=(0)2*infinity=can be any thing (V=IR)
so,is power consumed zero or any thing?

Last edited by a moderator: Nov 5, 2014
2. Nov 5, 2014

### CWatters

A resistor dissipates power in the form of heat (eg it gets warm or even hot). Would an open circuit get hot?

3. Nov 5, 2014

### CWatters

power=I2*R

Consider what happens as R approaches infinity and I approaches zero. Lets say you start with some value of R and then keep doubling it. At each step the current halves but the power changes by how much ? Work it out.

4. Nov 7, 2014

### Sunny Singh

Here the current does not tend to zero but is exactly 0. Hence, 0*R where R tends to infinity is exactly zero, not just any value. So power dissipated must be zero. if i would have tend to zero, i.e, went very near zero then i*Rwould have taken any value..