Question

Two bulbs have the following ratings:
40 W, 220 V
20 W, 100 V
The ratio of their resistance is
(a) 1:2
(b) 2:1
(c) 1:1
(d) 1:3​

Answer 1

Answer:

40w, 220v=1:1and 20w, 100v=1:2

Explanation:

hope it help you

Answer 2

Answer:

Power of 1 bulb=40W in 220V so

$p = {v }^{2} \div r$

so

R=v^2÷p so

R=(220×220)÷40=1210ohm

Power of bulb 2=20W in 100v

So

r=(100×100)÷20

r=500ohm

Now

R:r=1210:500=121:50

None of answer is correct.