If voltage across a bulb rated $220 \,V$- $100\, W$ drops by $2.5\%$ of its rated value, the percentage of the rated value by which the power would decrease is
- $20\,\%$
- $2.5\,\%$
- $5\,\%$
- $10\,\%$
The Correct Option is C
Solution and Explanation
As the resistance of the bulb is constant
$\therefore \frac{\Delta P}{P}=\frac{2\Delta V}{V}$
$\%$ decrease in power $=\frac{\Delta P}{P} \times 100$
$=\frac{2\Delta V}{V}\times 100$
$=2\times2.5\%=5\%$
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Concepts Used:
Current Electricity
Current electricity is defined as the flow of electrons from one section of the circuit to another.
Types of Current Electricity
There are two types of current electricity as follows:
Direct Current
The current electricity whose direction remains the same is known as direct current. Direct current is defined by the constant flow of electrons from a region of high electron density to a region of low electron density. DC is used in many household appliances and applications that involve a battery.
Alternating Current
The current electricity that is bidirectional and keeps changing the direction of the charge flow is known as alternating current. The bi-directionality is caused by a sinusoidally varying current and voltage that reverses directions, creating a periodic back-and-forth motion for the current. The electrical outlets at our homes and industries are supplied with alternating current.