Electrical – How to find the power rating of the following circuit diagram


How do you find the power rating for lamp 1 and lamp 2 and could you please explain exactly how you do it?
enter image description here

Best Answer

I will not provide the direct answer as this is obviously a homework.

"Power rating" refers to the minimum power that a device can dissipate. When powered, a lamp consume energy and transforms it into light and heat. For this kind a basic problem, we mostly assume that all the energy goes into heat.

The dissipated power is measured in Watts and correspond to the amount of energy per seconds that the lamp will converts to heat. If the lamp is small, or made of plastic for example, it may not be able to dissipate that heat, which mean it will burn (or damaged at least). If it's big enough, or installed on a radiator, it may not burn and the temperature will stabilize before it burns.

An electrical component normally have the capacity to dissipate a specific amount of power. For instance, we can say : this lamp is able to dissipate 90W. More than that, it will burn.

In you problem, finding the power ratings means finding the amount of power (watts) that is consumed by the lamps. Then you can say, this lamps needs to dissipate at least this amount of power.

Electrically speaking, the power dissipated by a element is given by the product of voltage and current across your lamp.


Just find the voltage around each lamps and multiply by the current going across it