"Find the Current in a 25mH Inductor Circuit

  • Thread starter Thread starter hotstuff
  • Start date Start date
  • Tags Tags
    Revision
Click For Summary
SUMMARY

The discussion centers on calculating the current in a circuit containing a 25mH inductor, a 20-ohm resistor, and a 15V power supply after the switch is closed at t=0. The current at t=7 seconds is stated to be 750 mA. The calculation involves understanding the time constant of the RL circuit and the exponential growth of current over time, which approaches a steady-state value as time progresses. Key parameters include the inductance (L = 25mH), resistance (R = 20Ω), and the applied voltage (V = 15V).

PREREQUISITES
  • Understanding of RL circuit dynamics
  • Knowledge of Kirchhoff's voltage law
  • Familiarity with exponential functions and time constants
  • Ability to apply the formula for current in an RL circuit: i(t) = (V/R)(1 - e^(-Rt/L))
NEXT STEPS
  • Study the derivation of the current formula for RL circuits
  • Learn about the time constant in RL circuits and its significance
  • Explore the behavior of current at t=0 and t=infinity in RL circuits
  • Investigate the impact of varying resistance and inductance on circuit behavior
USEFUL FOR

Electrical engineering students, circuit designers, and anyone interested in understanding the transient response of RL circuits.

hotstuff
Messages
10
Reaction score
0
hi okay i have a question, it is an old test question so it would be nice is someone ans b4 8am cos that is when the test it but if not that is fine just incase someone is surfing this website at this time.. ha.n e ways the question is a 25mH inductor is connected in series with a 20ohm resisto thru a 15v power supply and a swiitch. if the switch is closed at t= 0 what is the current at t = 7 the ans is 750 but do not know how was derived. thks.
 
Physics news on Phys.org
Show me your efforts
 
hotstuff said:
hi okay i have a question, it is an old test question so it would be nice is someone ans b4 8am cos that is when the test it but if not that is fine just incase someone is surfing this website at this time.. ha.n e ways the question is a 25mH inductor is connected in series with a 20ohm resisto thru a 15v power supply and a swiitch. if the switch is closed at t= 0 what is the current at t = 7 the ans is 750 but do not know how was derived. thks.
What is the current when t=0?
What is the current when t=infinity?
if i(0)<i(7)<i(infinity)
Where in this range do you expect i(7) to be?
What is i'(7)?
How does i(t) evolve over time?
 

Similar threads

Replies
34
Views
8K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 22 ·
Replies
22
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
8K
  • · Replies 12 ·
Replies
12
Views
10K
  • · Replies 6 ·
Replies
6
Views
8K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 13 ·
Replies
13
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K