PHYSICS TALK

The power supplied to a circuit can be calculated using the following equation:

P = IV

where P is power in watts (W),

I is current in amperes (A), and

V is voltage in volts (V)

 

This equation may be rearrange to calculate the value of any of the terms.

Example:

A current of 0.83 A flows in a light bulb operating in a 120-V circuit.
Calculate the power of the light bulb.

P = IV

= 0.83 A X 120 V

= 100 W

The load limit of the electrical system for the universal dwelling is set at 2400 W, as outlined in the chapter scenario. It is also established by the design of the windmill power plant that 120 V will be applied to circuits within the dwelling. In this activity you learned what load limit means, and how to relate it to current and voltage. If the people in the dwelling try to run appliances that require more than 2400 W, the fuse will blow. In your home, you can always choose a different line to run the extra appliances. With only one generator, this is not an option in the universal dwelling. This will have direct application soon when you begin selecting appliances to be used in the dwelling.