Question

two bulbs of 100w and 40w respectively connected in series across a 230v supply which bulb will glow bright and why?

Answer 1

Hey here is your answer-

There’s this formula of power versus voltage and resistance:

P = V^2/R

For the 100W bulb:

100 = 230^2/R

100 = 52900/R

R = 529 ohms

For the 40W bulb:

40 = 230^2/R

40 = 52900/R

R = 1322.5 ohms

The total current produced by the resistor in series:

I = V/R

I = 230/(529+1322.5)

I = 0.124 Amps

Now we will calculate the power in each bulb by using voltage divider.

100W bulb:

V = V(100W) / (V(100W) + V(40W)) * 230

V = 529/(1322.5+529) * 230 = 65.71 Volts

P = V * I = 65.71 *0.124 = 8.14 Watts

40W bulb:

V = V(40W) / (V(100W) + V(40W)) * 230

V = 1322.5/(1322.5+529) * 230 = 164.28 Volts

P = V * I = 164.28 *0.124 = 20.37 Watts

Therefore, the brigher bulb will be the 40W bulb.



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