If two electric bulbs have 40 W and 60 W...

If two electric bulbs have 40 W and 60 W rating at 220 V , then the ratio of their resistances will be

A

10 ohm

B

20 ohm

C

30 ohm

D

40 ohm

Verified by Experts

The correct Answer is:

C

`i=90/30 = 3A, R_(b) = (30)^(2)/90 =(30 xx 30)/90 = 10 Omega`
`i=120/(10+ R) rArr 3 = 120/(10+ R) rArr R = 30 Omega`

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