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- PHY102 Physics II © Dr.Cem Özdoğan
- 26-7 Power in Electric Circuits
- A battery “pumps” charges through the resistor (or any device), by producing a potential difference V between points a and b.
- A steady current i is produced in the circuit, directed from terminal a to terminal b.
- The amount of charge dq that moves from terminals a to b in time interval dt is equal to i dt.
- Its electric potential energy decreases in magnitude by the amount;
- The power P (rate of electrical energy transfer) dU/dt, given by
- How much work does the battery do to move a small amount of charge dq from b to a?
- dW = –dU = -dq×V = (dq/dt)×dt×V= iV×dt
- The battery “power” is the work it does per unit time:
- P = dW/dt = iV