The Direction and magnitude of current in the inductor

In summary, the current in an inductor changes with time based on the equation ε = -L* dI/dt, where ε represents the induced emf, L is the inductance, and dI/dt is the rate of change of current. The negative sign in the equation causes the current to flow in the opposite direction of the induced emf. This explains why the current in the given diagram is increasing rather than decreasing, as indicated by option D in the possible answers. Additionally, knowing the direction of the induced emf can help determine the direction of current flow in an inductor.
  • #1
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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  • #2
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.
 
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  • #3
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.
 

1. What is an inductor?

An inductor is an electrical component that is used to store energy in the form of a magnetic field. It is typically made up of a coil of wire and is often used in electronic circuits to control the flow of current.

2. How does an inductor affect the direction and magnitude of current?

An inductor resists changes in current and can cause current to lag behind the applied voltage. This means that the direction and magnitude of current in an inductor will depend on the voltage applied and the inductance of the component.

3. What factors affect the direction and magnitude of current in an inductor?

The direction and magnitude of current in an inductor can be affected by the inductance of the component, the voltage applied, the frequency of the current, and the resistance of the circuit.

4. How is the direction and magnitude of current in an inductor measured?

The direction and magnitude of current in an inductor can be measured using a multimeter or other measuring device. The inductance of the component can also be measured using specialized equipment.

5. What are some practical applications of understanding the direction and magnitude of current in an inductor?

Understanding the direction and magnitude of current in an inductor is important for designing and troubleshooting electronic circuits. It is also used in the design of various devices such as transformers, motors, and generators.

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