"Find the Current in a 25mH Inductor Circuit

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A 25mH inductor is connected in series with a 20-ohm resistor and a 15V power supply. When the switch is closed at t=0, the current begins to increase according to the inductor's time constant. The expected current at t=7 seconds is 750 mA, but the user is unsure how to derive this value. The current at t=0 is 0 A, and it approaches its maximum value at t=infinity, which can be calculated using the formula I = V/R. The discussion emphasizes understanding the evolution of current over time in an RL circuit.
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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.
 
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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?
 

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