Two bulbs of 500 watt and 200 watt are manufactured to operate on 220 volt line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are joined in parallel and secondly in series, will be

Resistance R1 of 500 W bulb =  2202500Resistance R2 of 200 W bulb =  2202200When joined in parallel, the potential difference across both the bulbs will be same.Ratio of heat produced =   V2/R1V2/R2 = R2R1= 52when joined in series, the same current will flow through both the bulbs.Ratio of heat produced =   i2R1i2R2 = R1R2= 25