Question

A microwave oven running at 60 % efficiency delivers 900 w of energy per second to the interior. find the power drawn from the source.

Answer 1

The microwave has 60% efficiency, this means that the power delivered (P=900 W) is 60% of the original power of the source, while the other 40% is dissipated.
We can write it this way:

`P= 0.60 P_(i)`
where
`P_i` is the power of the source, which we can find by re-arranging the equation:

`P_i = (P)/(0.60)= (900 W)/(0.60)=1500 W`