Please explain the concept of Power.
When do we use V2/R and I2R.
Consider this problem:
4 resistors (bulbs) are connected in series and then in parallel. What is the ratio of the heat produced in series and in parallel?
The answer has used V2/R i.e. power is inversely proportional to resistance.
Why cant i use I2R, since the current through the resistors is the same in series?

Please explain.

Question

Please explain the concept of Power.
When do we use V2/R and I2R.
Consider this problem:
4 resistors (bulbs) are connected in series and then in parallel. What is the ratio of the heat produced in series and in parallel?
The answer has used V2/R i.e. power is inversely proportional to resistance.
Why cant i use I2R, since the current through the resistors is the same in series?

Please explain.

anonymous · Answer

Please give some examples to clear the concept.

anonymous · Answer

The problem says they are first connected in series (currents are the same) and next they are connected in parallel (what are the currents then?) where the voltage drops are the same. Use what you want, but be careful of what the equivalent resistances are...

anonymous · Answer

Thank you, I had not taken the resistances into consideration.

anonymous · Answer

both will give same result if u will find the correct value of all the parameters

anonymous · Answer

we should use v^2/r when voltage and resistance are given and i^2r when current and resistance are given