Question

An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 2 resistor. The ratio of
the currents at time t = 0 and at t = 40 s is close to : (Take e2 = 7.389)
А
1.46
B
1.06
c
0.84
D
1.15​

Answer 1

Answer:

c is the answer

Explanation:

mark me as brain list

Answer 2

Explanation:

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

• We have τ = L / R
•                   = 10 x 10^-3 / 5
•                   = 0.01 / 5
•                   = 0.002
• So i = io(1 – e^t/0.002)
•        = io (1 – e^-500t)
•       So at t = 40 s
• So i40 = io (1 – e^-500 x 40)
•           = 20 / 5 (1 – e^-20000) [ I = V/R)
•           = 4 (1 – e^-20000)
• At t = infinity we have,
• So i infinity = io (1 – e^-t/τ)
•                     = io (1 – e^-infinity)
•                    = 20/5 (1 – 0)
•                    = 4
• So I infinity / i40 = 4 / 4 (1 – e^-20000)
•                              = 1 / 1 – e^-20000
• Or 1 – e^-20000 < 1

Reference link will be

https://brainly.in/question/13605628