1.

Two electric lamps are rated as 220V,100W and 220V, 40W respectively. Their electric resistances are

Answer»

`484 Omega,1210 Omega`
`2.2 Omega,5.5 Omega`
`45.5 Omega 7.3 Omega`
100W,40W

Solution :RESISTANCE `R=V^2/P` where V= Voltage /potential DIFFERENCE and P=power
`therefore` ELECTRICAL resistance of 100W lamp `R_1=V^2/P_1=(220 TIMES 220)/100=484 Omega`
and electrical resistance of 40W lamp, `R_2=V^2/P_2=(220 times 220)/40=1210 Omega`


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