Electric Circuits - Mission EC3 Detailed Help


When plugged into a 120-Volt outlet, a light bulb does 100 Joules of work each second that it is lit. What is the power of the light bulb?


 
Definition of Power:
Power is the rate at which work is done upon an object. As applied to electrical circuits, electrical power is the rate at which work is done upon a charge. The work done upon a charge results in a change in the electric potential energy of the charge. Thus, power can be defined in electrical terms as the rate at which a charge changes its electric potential energy.


 
Power (P) is the rate at which a charge changes its electric potential energy (∆E) as it moves from one location to another location. This can be expressed as

P = ∆E / t.


 
Light bulbs have a power rating. The power rating describes the rate at which the light bulbs uses the electrical energy of moving charge to produce light energy (and thermal energy). A 60-Watt bulb will consume 60 J of electrical energy per second of time when plugged into a typical U.S. outlet. As descried in the Formula Frenzy section, the power rating is simply the ratio of energy used per time of use.