Question

The r.m.s. value of an ac of 50 Hz is 10 amp. The time taken by the alternating current in reaching from zero to maximum value and the peak value of current will be

• A. 2 × 10^–2 sec and 14.14 amp
• B. 1 × 10^–2 sec and 7.07 amp
• C. 5 × 10^–3 sec and 7.07 amp
• D. 5 × 10^–3 sec and 14.14 amp

Answer 1

Answer: (D)

5 × 10^–3 sec and 14.14 amp

Answer 2

Time taken by the current to reach the maximum value

$t = \frac { T } { 4 } = \frac { 1 } { 4 v } = \frac { 1 } { 4 \times 50 } = 5 \times 10 ^ { - 3 } \mathrm { sec }$

and $i _ { o } = i _ { r m s } \sqrt { 2 } = 10 \sqrt { 2 } = 14.14$amp