current through inductor

Discussion in 'Homework Help' started by vvkannan, Oct 22, 2008.

1. vvkannan Thread Starter Active Member

Aug 9, 2008
138
11
I have a doubt about regarding inductors
If i connect a 1v source to an 1H inductor (without a resistor) would the current vs time(x axis) graph be a straight line with slope 'one' passing through the origin before reaching the curent reaches a constant value?

Apr 20, 2004
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3. vvkannan Thread Starter Active Member

Aug 9, 2008
138
11
Thank you for replying.I meant to ask what would exactly happen if there is nothing in the circuit except the constant voltage source and inductor.
The inductor would oppose the current initially.so zero current.and at steady state say a constant current flows.In between (though a very small time) will it be a straight line(i.e) a line with slope 1 if voltage is 1v and inductance is 1H according to the equation i=(1/L)*(integral(V dt)).

4. mik3 Senior Member

Feb 4, 2008
4,846
67
It will be a straight line to a close approximation because inductors are not purely inductive, they have resistance too due to the copper wire.

5. steveb Senior Member

Jul 3, 2008
2,433
469
Strictly speaking, the response is an exponential shape, but initially is will look very close to a straight line. This assumes you are asking about doing an actual experiment, which your question seems to imply.

Obviously, theoretically, a perfect inductor and perfect voltage source would create a straight line (with slope 1) that goes to infinity and never reaches a constant value.

6. vvkannan Thread Starter Active Member

Aug 9, 2008
138
11
I understand.Thank you

7. hgmjr Moderator

Jan 28, 2005
9,030
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It is my understanding that an ideal inductor when driven from an ideal voltage source is described by the equation:

The slope in this case would vary depending on the value of V and L. There are of course values of V and L that would produce a slope of 1. An example would be a 1H inductor together with a 1V source.

hgmjr

8. steveb Senior Member

Jul 3, 2008
2,433
469
Yes, that's what I meant, but I should have been more clear. His question specifically mentions 1V supply with 1 H inductor. So, I was just trying to address his question.