Magnetic field and direction of motion

In summary, a potential difference can be induced across a wire when the angle between the direction of motion and the magnetic field is 0 and 90 degrees. For maximum destructive interference, two wavelengths must be out of phase by 180 degrees. In a standing wave, the phase difference between two waves at a node is 180 degrees.
  • #1
UrbanXrisis
1,196
1
Which two angles between the direction of motion of a wire and a magnetic field can a potential difference be induced across the wire?

1. 0 and 45
2. 0 and 90
3. 45 and 90
4. 45 and 180
 
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  • #2
motional EMF

For a motional EMF to be induced across the wire, the wire must have a component of motion perpendicular to the magnetic field.
 
  • #3
So it should be 0 and 90. By how many degrees should two wavelengths be out of phase to produce maxium destructive interference?
 
  • #4
UrbanXrisis said:
So it should be 0 and 90.
Nope. 0 degrees would be parallel to the magnetic field.
By how many degrees should two wavelengths be out of phase to produce maxium destructive interference?
Imagine (better yet, draw) two identical waves, one on top of the other. Have far would you have to slide one over to just cancel the other? (Hint: what fraction of a wavelength?)
 
  • #5
half a wavelength?
 
  • #6
so 180 degrees right?
 
  • #7
UrbanXrisis said:
half a wavelength?
You got it! How many degrees is that?
 
  • #8
UrbanXrisis said:
so 180 degrees right?
Right again!
 
  • #9
what if two waves traveling in the same medium interfere to produce a standing wave. What is the phase diference in degrees between the two waves at a node?
 
  • #10
standing waves: nodes and anti-nodes

UrbanXrisis said:
what if two waves traveling in the same medium interfere to produce a standing wave. What is the phase diference in degrees between the two waves at a node?
In a standing wave, there are nodes and anti-nodes. The nodes are the places where you see minimum or no amplitude--which means maximum destructive interference; the anti-nodes are the places with maximum amplitude--thus constructive interference.
 
  • #11
how do you find the phase difference though?
 
  • #12
UrbanXrisis said:
how do you find the phase difference though?
Reread the thread and I'll bet you can figure it out.
 

1. What is a magnetic field?

A magnetic field is a region in space where a magnetic force can be detected. It is created by moving electric charges or by the intrinsic magnetic dipole moment of elementary particles.

2. How does a magnetic field affect the direction of motion?

A magnetic field can exert a force on a moving charged particle, causing it to change direction. This is known as the Lorentz force and is perpendicular to both the magnetic field and the velocity of the particle.

3. What is the difference between a magnetic field and an electric field?

A magnetic field is created by moving electric charges, while an electric field is created by stationary or non-moving charges. Additionally, the force exerted by a magnetic field is perpendicular to the direction of motion, while the force exerted by an electric field can be in any direction.

4. How is the direction of a magnetic field determined?

The direction of a magnetic field is determined by the direction in which a compass needle would point in that field. The north pole of a compass needle points towards the south pole of a magnetic field.

5. Can the direction of a magnetic field change?

Yes, the direction of a magnetic field can change over time. This can occur due to the movement of electric charges or changes in the orientation of magnetic dipoles. Additionally, the direction of a magnetic field can also be affected by the presence of other magnetic fields.

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