Inducing a magnetic field with a wire due to flux

In summary, a stationary loop of wire placed in a magnetic field directed into the page will have a clockwise current if the magnetic field is decreasing. This is due to Lenz's law, which states that the induced current creates a field opposing the change in the inducing magnetic field. Therefore, the change in the field, which is "out of the page" in this case, results in a current that goes into the page to counteract the change.
  • #1
wosman
3
0

Homework Statement


A stationary loop of wire is placed in a magnetic field directed into the page. The current in the loop of wire:

and then it lists 4 multiple choice options. the answer is: the current in the loop of wire is clockwise if the magnetic field is decreasing.


Homework Equations


non really


The Attempt at a Solution



My issue is when trying to solve this i realized that if the current is clockwise then a magnetic field will be created that is going into the page. BUT lenz's law states the induced current will create a magnetic field OPPOSING the inducing magnetic field.

So I would have answered the question by saying the current would be counterclockwise since this would make a magnetic field that comes out of the page (i.e. opposing the inducing magnetic field)

I'm not sure why the answer is the one that is written. Any help is appreciated.
 
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  • #2
Welcome to PF.
wosman said:
... lenz's law states the induced current will create a magnetic field OPPOSING the inducing magnetic field...
Not quite. The induced current creates a field opposing the change in the inducing magnetic field.

The inducing field is into the page, but decreasing. Therefore the change in this field is in what direction?
 
  • #3
Redbelly98 said:
Welcome to PF.

Not quite. The induced current creates a field opposing the change in the inducing magnetic field.

The inducing field is into the page, but decreasing. Therefore the change in this field is in what direction?

The change is "out of the page" thus the created field opposes this by going into the page!

Thanks so much!
 

1. What is flux and how does it relate to inducing a magnetic field with a wire?

Flux is a measure of the strength of a magnetic field passing through a given area. When a current-carrying wire is placed in a magnetic field, the flux through the wire changes, which in turn induces a magnetic field in the wire.

2. How does the direction of the magnetic field induced by a wire relate to the direction of the current in the wire?

The direction of the magnetic field induced by a wire is perpendicular to both the direction of the current and the direction of the magnetic field that the wire is placed in. This is known as the right-hand rule.

3. What factors affect the strength of the magnetic field induced by a wire?

The strength of the magnetic field induced by a wire is directly proportional to the current in the wire, the number of turns in the wire, and the permeability of the material surrounding the wire. It is also inversely proportional to the distance from the wire.

4. What is the practical application of inducing a magnetic field with a wire due to flux?

Inducing a magnetic field with a wire due to flux is commonly used in electromagnets, which are used in a variety of applications such as electric motors, generators, and MRI machines. It is also used in wireless charging technology.

5. How is the induced magnetic field in a wire affected by the shape of the wire?

The shape of the wire can affect the strength of the induced magnetic field. For example, a wire coiled into a solenoid will have a stronger magnetic field than a straight wire, due to the increased number of turns. However, the direction of the magnetic field will still follow the right-hand rule regardless of the wire's shape.

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