Question 214: AC fundamentals

Question

An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 $$\Omega $$
resistor. The ratio of the currents at time t = $$\infty $$ and at t = 40 s is close to : (Take e2 = 7.389)

Accepted Answer

i = i
0
(1 - $${e^{ - {{Rt} \over L}}}$$)
i
$$\infty $$
= i
0
(1 - $${e^{ - \infty }}$$) = i
0
$$ 	herefore $$ $${{{i_\infty }} \over {{i_{40s}}}}$$ = $${{{i_0}} \over {{i_0}\left( {1 - {e^{ - {{5 	imes 40} \over {10 	imes {{10}^{ - 3}}}}}}} ight)}}$$
= $${1 \over {\left( {1 - {e^{ - 2000}}} ight)}}$$ $$ \approx $$ 1
Then most appropriate option is 1.06

Answer

1.06

Answer

0.84

Answer

1.15

Answer

1.46

AC fundamentals

An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 $\Omega resistor. The ratio of the currents at time t = \infty $ and at t = 40 s is close to : (Take e2 = 7.389)

Choose the correct answer: