Did I Solve the RL Circuit Problem Correctly?

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
3 replies · 3K views
musiliu
Messages
43
Reaction score
0

Homework Statement



An emf of 10V is connected to the RL circuit (R = 10 Ohms, L = 1.0 H)
shown below for long, long time (the switch is in position 1). Then, at t = 0
the switch is thrown into position 2. Find the current in the circuit at t = 0.2
s. When will the current drop to 0.001 A?
[PLAIN]http://img132.imageshack.us/img132/5139/physicsproblem.jpg

Homework Equations



"Discharge" of RL circuit: I(t) = I0e-Rt/L

The Attempt at a Solution



Part 1:
This looks like simple plug-in problem:
I0 = E / R after "long, long time"
E = 10 V, R = 10 Ohms, L = 1 Henry
I(0.2) = 0.135 A

Part 2:
I set I = .001 A and solved for t:
t = 0.691 s

Are my answers correct and did i do this problem correctly?
 
Last edited by a moderator:
on Phys.org
What did you use as Io, how did you do part 2?
 
I used Io equal to E / R, voltage over resistance from Ohm's Law, because for "long, long time", the initial current is equal to that...

so is my answer correct?