Question

you have two electrical lamps having rating 40 volt to 20 volt and 60 volt to 220 volt which of the two have higher resistance give reason for your answer if these two lamps are connected with the source of 220 volt which will glow brighter.
Only Right answer please ​

Answer 1

Correct Question

You have two electrical lamps having rating 40W of 220V and 60W of 220V which of the two have higher resistance give reason for your answer. If these two lamps are connected with the source of 220V which will glow brighter.

Solution

Given that, two electrical lamps having rating 40W of 220V and 60W of 220V.

P1 = 40W, P2 = 60W and V1 = V2 = 220V

We have to find the which of the two have higher resistance.

Relation between P, V and R is:

P = V²/R

For 1st lamp:

P1 = (V1)²/R1

40 = (220)²/R1

R1 = 48400/40

R1 = 1210 ohm

For 2nd lamp:

P2 = (V2)²/R2

60 = (220)²/R2

R2 = 48400/60

R2 = 806.67 ohm

Also, resistance is inversely proportional to power. So, the lamp having less power have more resistance.

Therefore, the resistance of first lamp is higher or more.

In second part of the question we have to if these two lamps are connected with the source of 220 volt which will glow brighter.

So, if both the lamps are connected in the same source of 220V then the lamp having less resistance will glow brighter.