A `500 W` heating unit is designed to operate from a `200 V` line . By what percentage will its heat output drop if the line voltage drops to `160 V`? Find the heat produced by it in `10 min.`

Explanation

Actual power consumed is
`P = (( V)/( V_(0)))^(2) p_(0) = ((160)/(200))^(2) 500 = 320 W`.
Heat output drop is `500 - 320 = 180 W`.
Percentage heat drop is
`(180)/(500) xx 100 = 36%`
Thus , heat produced in `10 min ( 600 S)` is given by
` H = 320 xx 600 = 192000 J = 192 kJ`