Question

if the filament resistance of bulbs of 400 W and 200W design to operate on the same voltage,are R1 and R2 respectively then

Answer 1

Final Answer : R1/R2 = 1/2

Understanding :
1) Power of Bulbs is inversely proportional to Resistance.
P proportional to 1/ R.


Steps :
1) R1/R2 = P2/P1= 200W/400W = 1/2

Answer 2

Dear Student,

◆ Answer -

R1:R2 = 1:2

● Explanation -

Power of the bulb is given by -

P = V²/R

For 400 W bulb,

400 = V²/R1

For 200 W bulb,

200 = V²/R2

Dividing two equations,

400 / 200 = (V²/R1) / (V²/R2)

2 = R2/R1

R1/R2 = 1/2

Hence R1:R2 = 1:2.

Thanks dear. Hope this helps..