Induced current and mag. f

The camera sees the induced current going counterclockwise as you bring the magnet closer to the coil. But from our point of view, looking down at the coil, the current is going clockwise. So it depends on your point of view.In summary, the conversation discusses the direction of the induced current and magnetic field in a coil when a magnet is brought closer or farther away from the coil. The right hand rule is used to determine the direction of the current and it is dependent on the change in flux through the coil. The passage from Wikipedia is correct, but the direction of the current may appear different depending on the point of view.
  • #1
36
0
Please see question at . . . . http://www.flickr.com/photos/37144556@N07/3476115300/sizes/o/ [Broken]

(i) I am not sure which hand rule to use??
I think its the right hand rule, so does that mean the answer to question (i) is clockwise.

(ii) is the answer " in a circluar direction perpendicular to the wire?? as seen here http://etc.usf.edu/clipart/36000/36057/mag_field_36057_lg.gif

Thanks.
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
jayjay112 said:
(i) I am not sure which hand rule to use??
I think its the right hand rule, so does that mean the answer to question (i) is clockwise.
You would use a right hand rule, but the answer is not clockwise. How is the field through the loop changing? The induced current acts to oppose that change.

(ii) is the answer " in a circluar direction perpendicular to the wire?? as seen here http://etc.usf.edu/clipart/36000/36057/mag_field_36057_lg.gif
No. Realize that these two questions are related. The induced current creates the induced magnetic field.
 
  • #3
If you bring the magnet away from the coil, you are decreasing the flux through the coil. Therefore, the current should be induced in the clockwise direction.

So how is it going anticlockwise, what is the induced current opposing?
 
  • #4
jayjay112 said:
If you bring the magnet away from the coil, you are decreasing the flux through the coil.
Right! So current must be induced in a direction that will increase the flux through the loop. Using the right-hand rule, what direction will that induced current flow?
Therefore, the current should be induced in the clockwise direction.
How did you conclude this?
 
  • #5
Doc Al said:
How did you conclude this?

I had my hand the wrong way, so my thumb should point up in the direction to compensate for the decrease in mag field therefore inducing a current to flow the direction of my fingers ie anticlockwise!

Which also means the induced mag field should point out of the page upwards.

So is this passage from wikipedia incorrect..."Take the north pole of a permanent magnet and a coil in front of it and put a microscopic camera on top of the magnet. As you bring the magnet closer to the coil, you are increasing the flux through the coil. Then by Lenz's law, the current will be in counterclockwise direction as viewed by the camera.
If you bring the magnet away from the coil, you are decreasing the flux through the coil. Therefore, the current should be induced in the clockwise direction as viewed from the camera."
 
  • #6
jayjay112 said:
I had my hand the wrong way,
D'oh!
so my thumb should point up in the direction to compensate for the decrease in mag field therefore inducing a current to flow the direction of my fingers ie anticlockwise!
Good!

Which also means the induced mag field should point out of the page upwards.
Right!
 
  • #7
Doc Al said:
D'oh!

Good!


Right!

Thanks for your help, appreciated.
 
  • #8
jayjay112 said:
So is this passage from wikipedia incorrect..."Take the north pole of a permanent magnet and a coil in front of it and put a microscopic camera on top of the magnet. As you bring the magnet closer to the coil, you are increasing the flux through the coil. Then by Lenz's law, the current will be in counterclockwise direction as viewed by the camera.
If you bring the magnet away from the coil, you are decreasing the flux through the coil. Therefore, the current should be induced in the clockwise direction as viewed from the camera."
No, that passage is OK. Note that the camera is on the magnet, so you're looking at the coil from underneath.
 

What is induced current?

Induced current is a flow of electric charge that is created in a conductor when it is exposed to a changing magnetic field.

What is the relationship between induced current and magnetic field?

The strength of the induced current is directly proportional to the rate of change of the magnetic field, as described by Faraday's law of electromagnetic induction.

How is induced current different from direct current?

Induced current is created by a changing magnetic field and is not dependent on a continuous power source, unlike direct current which is produced by a constant voltage source.

How is induced current used in everyday life?

Induced current is used in a variety of devices such as generators, transformers, and electric motors. It is also used in wireless charging technology for electronic devices.

What factors affect the strength of induced current?

The strength of induced current is affected by the strength of the magnetic field, the speed at which the field changes, and the properties of the conductor such as its length and material.

Suggested for: Induced current and mag. f

Back
Top