If voltage across a bulb rated 220 ,V, 100 ,W | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) The power consumed by a bulb is given by $P = \frac{V^2}{R}$, where $V$ is the voltage and $R$ is the constant resistance of the bulb.Taking the l

Vedclass · Accepted Answer

$5$

Vedclass · Answer

(B) The power consumed by a bulb is given by $P = \frac{V^2}{R}$, where $V$ is the voltage and $R$ is the constant resistance of the bulb.Taking the logarithmic derivative, we get $\frac{dP}{P} = 2 \frac{dV}{V}$.Here, the percentage change in voltage is $\frac{dV}{V} = -2.5 \% = -0.025$.Therefore, the percentage change in power is $\frac{dP}{P} = 2 	imes (-2.5 \%) = -5 \%$.The negative sign indicates a decrease in power.Thus, the power decreases by $5 \%$ of its rated value.

If voltage across a bulb rated $220 \,V, 100 \,W$ drops by $2.5 \%$ of its rated value, then the percentage of the rated value by which the power would decrease is (in $\%$)

Similar Questions

An electric kettle takes $4\, A$ current at $220\, V$. How much time will it take to boil $1\, kg$ of water from room temperature $20\, ^\circ C$? The temperature of boiling water is $100\, ^\circ C$. (Assume specific heat of water $c = 4200\, J/kg\, ^\circ C$)

The heat produced by a $100\, W$ heater in $2\, minutes$ will be equal to:

The emf of a battery is $2\, V$ and its internal resistance is $0.5 \,\Omega$. The maximum power which it can deliver to any external circuit will be ............. $watt$.

If the power in the external resistance $R$ is maximum,then which of the following statements are correct?
$(i) R = r$
$(ii)$ Power in $R$ is $\frac{E^2}{4R}$
$(iii)$ Input power is $\frac{E^2}{2R}$
$(iv)$ Efficiency is $50\%$

How many $60 \,W$ bulbs may be safely run on $220 \,V$ using a $5 \,A$ fuse?

Vedclass Test Series

Exam Paper Generator

Online Exam Module