A resistance of 40Ω is connected to a source of alternating current rated 220 V, 50 Hz. Find the time taken by the current to charge from its maximum value to the rms value :

Option 1 - 2.5 ms

Option 2 - 1.25 ms

Option 3 - 2.5 s

Option 4 - 0.25 s

3 Views|Posted 6 months ago

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Answered by

Vishal Baghel | Contributor-Level 10

6 months ago

Correct Option - 1

Detailed Solution:

Let l = l₀ cos wt

l = l₀, at t₁ = 0

& $l = \frac{l_{0}}{\sqrt[]{2}}, a t ω t = \frac{π}{4} \Rightarrow t_{2} = \frac{π}{4 ω}$

$t_{2} = \frac{π}{4 ω} = \frac{π}{4} * \frac{T}{2 π} = \frac{T}{8}$

$t_{2} = \frac{1}{8} * \frac{1}{υ} (T = \frac{1}{υ})$

$t_{2} = \frac{1}{8 * 50}$

^{$t_{2} = \frac{1}{4 * 1 0^{+ 2}}$}

= 0.25 * 10^-2

t₂ = 2.5 ms

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