Calculate the amount of heat produced per second (in calories ) when a bulb of `100 W ,220 W` glows, assuming that only `20 %` of electric energy is connected into light `J = 4.2 J cal^(-1)`

Answer

`19.05 cal`

Explanation

Electric energy consumed per second `= 100 J`
Heat produced `= 80 % = (80)/(100) xx 100`
`= 80 J = (80)/(4.2) = 19.05 cal`