Question

The rms value of an arc of $50Hz$ is $10A$. The time taken by an alternating current in reaching from zero to maximum value and the peak value will be

• A. $2\times {10}^{-2}sand14.14A$
• B. $1\times {10}^{-2}sand7.07A$
• C. $5\times {10}^{-3}sand7.07A$
• D. $5\times {10}^{-3}sand14.14A$

Answer 1

The correct option is D $5\times {10}^{-3}sand14.14A$

from zero to maximum value is the $\frac{1}{4}$th of one complete cycle .
It has frequency of $50Hz$. Time period$\frac{1}{50}sec.$
The time taken by an alternating current in reaching from zero to maximum value$=\frac{1}{50}\times \frac{1}{4}=5\times {10}^{-3}sec$
$i_{rms}=\frac{i_{peak}}{\sqrt{2}}$
$i_{peak}=i_{rms}\sqrt{2}=10\times 1.414=14.14A$