MediumPhysicsHigh School (9–10)Electricity & Magnetism › Current ElectricityNumerical

A heater is marked 1320 W for a 220 V supply.

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

A heater is marked $1320\ \text{W}$ for a $220\ \text{V}$ supply. Find the current it takes, and the resistance of its coil.

Need a reminder? The key ideaShow

Joule's law: $H = I^2 R t = VIt = \dfrac{V^2}{R}\,t$ . Power $P = VI = I^2 R = \dfrac{V^2}{R}$ , in watts. A fuse, in the live wire, melts when the current is too large.

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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← An appliance takes 0.75 A from a 230 V supply.A bulb is marked 220 V, 40 W. Find the current it takes at 220 V. →

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