Question

The peak value of an alternating current is $5$A and its frequency is $60$Hz. Find its rms value and time taken to reach the peak value of current starting from zero.

• A. $2.536A;4.167ms$
• B. $3.536A;15ms$
• C. $6.07A;10ms$
• D. $3.536A;4.167ms$

Answer 1

Answer: (D)

The correct option is A $3.536A;4.167ms$
The RMS value of the current is given as:

$i_{rms}=\frac{i_0}{\sqrt{2}}=\frac{5}{\sqrt{2}}=3.536A$

The time period of the current is:

$T=\frac{1}{f}\Rightarrow \frac{1}{60}s$

So, the current takes one-fourth of the time period to reach the peak value starting from zero .

$t=\frac{1}{4\times 60}=4.167$ms.