Question

Three $100W,150V$ lamps are connected across $150V$ line.Find voltage across each and power disseminate in 3 bulbs.

Answer 1

Given, $150v,100w$

IF these three the first two are reliable to change according to a given, circuit but the resistance of a device is fairly constant.

Let us take $150-100$ so the resistance of the filament is:

Since we know that,

$p=\frac{v^2}{R}\Rightarrow R=\frac{v^2}{p}$ When $v=150v,p=100w$

$R=\frac{150\times 150}{100}=225\Omega$

Let the two bulbs are in series, the total resistance is$R^{\prime }=225+225=450\Omega$

Let them powered by $150$

Now, the current flow through the either $I=\frac{v}{R^{\prime }}=\frac{150}{450}=0.33A$

Since the bulbs are in series, the same amount of current flows each of them.

Since the two bulbs are identical, the voltage across each bulb is $v=IR=0.33\times 225=74.25v$

So, the power supplied:

$p=v\times I=I^{2}R={0.33}^2\times 225=24.5025watt$