The Direction and magnitude of current in the inductor

AI Thread Summary
The discussion centers on the behavior of current in an inductor, specifically why the current is increasing rather than decreasing despite its rightward direction. The equation ε = -L * dI/dt indicates that the induced emf opposes the change in current, leading to an increase in current when dI/dt is positive. The voltage in the circuit acts to the right, supporting the notion that the current is increasing. The correct answer to the posed question is that the current is increasing and leftward, reflecting the dynamics of inductive behavior. Understanding these principles is crucial for analyzing circuits involving inductors.
hidemi
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Homework Statement
The diagram (see attachment) shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

A. The current is constant and rightward
B. The current is constant and leftward
C. The current is increasing and rightward
D. The current is increasing and leftward
E. None of the above

The answer is D.
Relevant Equations
ε = -L* dI/dt
I understand that the current is going rightward because of the negative sign in the equation above, but why is the current increasing not decreasing?
The current doesn't stay constant because it changes with the time based upon the equation above again.
 

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hidemi said:
Homework Statement:: The diagram (see attachment) shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

A. The current is constant and rightward
B. The current is constant and leftward
C. The current is increasing and rightward
D. The current is increasing and leftward
E. None of the above

The answer is D.
Relevant Equations:: ε = -L* dI/dt

I understand that the current is going rightward because of the negative sign in the equation above, but why is the current increasing not decreasing?
The current doesn't stay constant because it changes with the time based upon the equation above again.
A good way to understand inductors is to impress a known current (for instance, using a high series resistance) and see what voltage obtains. In the example shown, the voltage acts to the right. You only have options for "current increasing", making dI/dt is positive. As L is also positive, e opposes the current direction by flowing to the left.
 
tech99 said:
A good way to understand inductors is to impress a known current (for instance, using a high series resistance) and see what voltage obtains. In the example shown, the voltage acts to the right. You only have options for "current increasing", making dI/dt is positive. As L is also positive, e opposes the current direction by flowing to the left.
Thank you so much.
 
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