Question

An electric bulb marked 40W-200V is used in a circuit of supply voltage 100V. Now its power is:

Answer 1

Answer:

Power of the bulb is 10 Watts.                

Explanation:

We have,

Power and voltage of electric bulb is 40 W and 200 V. Using this data we can find the resistance of the bulb.

Power, $P=\dfrac{V^2}{R}$

R is resistance

$R=\dfrac{V^2}{P}\\\\R=\dfrac{(200)^2}{40}\\\\R=1000\ \Omega$

The supplied voltage is 100 V.

Now power is given by :

$P=\dfrac{V^2}{R}\\\\P=\dfrac{100^2}{1000}\\\\P=10\ W$

So, now the power of the bulb is 10 Watts.