Power: P = VI

Power

The power of an appliance is the work it does in unit time — how fast it works, or the electrical energy it uses in unit time.

Figure to be added

Figure 10.2 — an appliance connected across a supply with potential difference V, taking a current I and giving out energy.

Power = potential difference × current

P = VI

With V in volts (V) and I in amperes (A), P is in watts (W).

Example 1 — a filament bulb on 12 V takes 2 A. Its power?

P = VI = 12 × 2 W

P = 24 W

Example 2 — a 2000 W oven on a 230 V supply. The current it takes?

2000 = 230 × I

I = 2000 ÷ 230 ≈ 8.7 A