Two resistors, and inductor and a source of emf are connected with two switches

Question

Two resistors, and inductor and a source of emf are connected with two switches as shown in the figure below. Their values are R_1 = 4.00 KOhm, R_2 = 2.00 KOhm, L = 18.0 mH, and epsilon = 36.0 V. At time t = 0.0 mus switch S_1 is closed. What is the current in the circuit at t= 4.00 mus? After sufficient time for the current in the circuit to reach steady state value, switch S_1 is opened while switch S_2 is simultaneously closed. What is the current through the resistor R_2 10.0 mus after S_2 is closed?

Explanation / Answer

8) given R1 = 4 kohm

R2 = 2 kohm

L = 18 mH

= 0.018 H

emf = 36 volts

Time constant of the ckt, T = L/(R1+R2)

= 0.018/(4000 + 2000)

= 3*10^-6 s 3 micro s

a) I = Imax*(1 - e^(-t/T))

= (36/(4000+2000))*(1 - e^(-4/3))

= 4.42*10^-3 A

b) Imax = 36/(4000+2000) = 6*10^-3 A

Time constant, T = L/R2 = 0.018/2000 = 9*10^-6 s

at t = 10 micro s

I = Imax*e^(-t/T)

= 6*10^-3*e^(-10/9)

= 1.98*10^-3 A

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.