Inductors physics forums

  • Thread starter dwn
  • Start date
  • #1
dwn
165
2

Homework Statement



A coil with an inductance of 2.0 H and a resistance of 10 ohm is suddenly connected to an ideal battery with E = 100 V. At 0.10 s after the connection is made, what is the rate at which:

(a) energy is being stored in the magnetic field, ans: 2.4*102
(b) thermal energy is appearing in the resistance, and ans: 1.5*102
(c) energy is being delivered by the battery? ans: 3.9*102

Homework Equations



UL=.5LI2
VR=E(1-e-t/tau)

The Attempt at a Solution



V=IR 100/10 = I = 10 A
UL= .5*2*102 = 100

Clearly I'm missing a step or another equation to derive the current because I don't believe 10 A is correct. Please advise!
 

Answers and Replies

  • #2
ehild
Homework Helper
15,543
1,909
10 A is the current after infinite time, and it is equal to Io= E/R. (E is the emf of the battery)

The current changes according to the function I=Io(1-e-t/τ).

You need to calculate the rate of changes of energies at t= 10 s.

ehild
 

Related Threads on Inductors physics forums

Replies
3
Views
9K
Replies
1
Views
892
Replies
3
Views
2K
  • Last Post
Replies
8
Views
622
  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
7
Views
1K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
2
Views
860
  • Last Post
Replies
2
Views
739
Top