# PHYSICS Lecture Notes - Lecture 10: Ground And Neutral, Electrical Network, Kilowatt Hour

## Document Summary

Starting with power, we have learned in the tutorial on work, energy and power that power is the rate of work done or rate of energy converted. Now, the equation for potential difference v between two points in a circuit is given by: E = qv which is equal to where v is the potential difference or voltage, e is the energy consumed (or work done in joule) and q is the charge in c (coulomb). If we substitute the above two equations, we"ll get p = qv / t. Now substitute q = it into the equation we just formed: p = vi. These equations will be very helpful to find the unknown (power in most cases). P = i2r (since v = ir) P = v2 / r (since i = v / r) A bulb is connected to 3 v battery of negligible internal resistance.