PhysicsChapter 7: Current Electricity
Power of A Device
Introduction
Electrical power is the rate at which a device transfers or converts electrical energy. P = Wt In an electric circuit: P = VI Using Ohm's law, for a resistor: P = I²R and: P = V²R Unit: watt (W)
Definition
Meaning of Power Rating
A **60 W lamp transfers approximately 60 J of energy each second** when operating at its rated conditions.
Worked Example
A device operates at: `V = 12 V` `I = 2 A` **P = VI** 0 **P = 24 W**
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Review the key facts, formulas and checks before you move on.Power of A Device
Sticky Notes · Quick Revision
P=VI
- P=VI
P=I²R
- P=I²R
P=V²/R
- P=V²R
1 W
- 1 J/s