Question

An electric bulb has marking 110V, 100W on it.
(a) How much energy is used per second by this bulb ?
(b) What is the resistance of this electric bulb

Answer 1

Need to FinD :-

• The energy is used per second by this bulb .
• The resistance of this electric bulb.

$\red{\frak{Given}}\Bigg\{ \sf The \ marking\ of\ the \: bulb \ is 110V , 100W .$

The given marking of the bulb is 110V ,100W . We know the rate of doing work is called Power or simply the rate by which energy is consumed is called power . Here 100W is the power of the bulb .

• It means 100J of energy is consumed by the bulb in 1 sec .
• Therefore answer of first question is 100J .

We know that ,

$\sf\longrightarrow Power =\dfrac{Voltage^2}{Resistance}$

• Here the voltage of the bulb is 110V , and the power is 100W . On substituting the respective values we have ,

$\\\sf\longrightarrow Power =\dfrac{Voltage^2}{Resistance} \\\\\\\sf\longrightarrow 100W =\dfrac{(110V)^2}{R} \\\\\\\sf\longrightarrow R =\dfrac{ 110 \times 110}{100}\\\\\\\sf\longrightarrow \underset{\blue{\sf Required\ Resistance }}{\underbrace{\boxed{\pink{\frak{ Resistance ( R) = 121\Omega }}}}}</p><p>$