Quick induced current from magnetic field question direction of current?

In summary, the RHR-1 states that the force acting on a charge in a magnetic field will result in a current moving counter-clockwise along the rod, as determined by the Lorentz force and Lenz's Law. The direction of the current is determined by the direction of the force and the attempt to counter its cause, which in this case is the increasing flux enclosed within the loop.
  • #1
michaelw
80
0
With RHR-1, if the rod moves to the right in a field coming into the page, the force will move positive charge up (in reality move negative electrons down) in the rod, and induce a current
but why is the current counter clockwise?
 

Attachments

  • nw0975-n.gif
    nw0975-n.gif
    5.5 KB · Views: 639
Physics news on Phys.org
  • #2
There are two ways to answer what I think is your question.

1) Think of the Lorentz force on a charge in a magnetic field, [itex]\vec{F} = q(\vec{v} \times \vec{B})[/itex]. Using the RHR tells you that the force acts upwards along the rod, making the current want to go up the rod and hence counter-clockwise. Taking this a step further, this Lorentz force merely results from an electric field that is set up in a moving conductor in a B-field. This electric field set up across the rod propagates through the rest of the loop, forcing the current to travel in the required direction.

2) Think of Lenz's Law. The current will be set up in the loop in a manner that attempts to counter its cause. The cause in this case, is the increasing flux (B.A) enclosed within the loop as the rod moves to the right. Hence, the current will go in a direction that will try to reduce this flux. So naturally, the current wants to induce a magnetic field in a direction opposite to the existing field. Again, you can use the right hand thumb rule to tell that it takes a counterclockwise current to induce a field coming out of the plane of the paper.
 
  • #3


The direction of the induced current can be determined using the Right Hand Rule (RHR-1) for electromagnetic induction. According to this rule, if the rod is moving to the right in a magnetic field that is coming into the page, the force on the positive charge will be upwards. This means that the positive charge will move in a direction perpendicular to both the direction of motion and the magnetic field.

Since the force on the positive charge is upwards, the direction of the induced current will be counterclockwise. This is because the direction of the current is always opposite to the direction of the force on the positive charge, as per the RHR-1. Therefore, the negative electrons in the rod will actually move in a downward direction, but the overall current will be counterclockwise.

In summary, the direction of the current is determined by the direction of the force on the positive charge, which is perpendicular to both the direction of motion and the magnetic field. This is why the current is counterclockwise in this scenario.
 

Related to Quick induced current from magnetic field question direction of current?

1. How is induced current created by a magnetic field?

Induced current is created when a conductor (such as a wire) moves through a magnetic field or when a magnetic field changes around a stationary conductor. This movement or change in magnetic field causes a force on the electrons in the conductor, which creates a flow of electricity, or current.

2. What is the direction of induced current in relation to the magnetic field?

The direction of induced current is determined by the right-hand rule. If you point your thumb in the direction of the magnetic field and your fingers in the direction of the conductor's movement, the direction your palm faces is the direction of the induced current.

3. How does the strength of the magnetic field affect induced current?

The strength of the magnetic field directly affects the magnitude of the induced current. A stronger magnetic field will create a larger force on the electrons, resulting in a greater current. Similarly, a weaker magnetic field will result in a smaller induced current.

4. What factors can affect the direction of induced current?

The direction of induced current can be affected by the direction and strength of the magnetic field, as well as the speed and orientation of the conductor in the magnetic field. Additionally, the material of the conductor and its resistance can also impact the direction of the induced current.

5. How is induced current used in practical applications?

Induced current has many practical applications, such as in generators, transformers, and electric motors. It is also used in technologies such as magnetic resonance imaging (MRI) and induction cooktops. Induced current can also be harnessed for renewable energy production through methods such as electromagnetic induction in hydroelectric power plants.

Similar threads

  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
341
Replies
8
Views
528
  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
350
  • Introductory Physics Homework Help
Replies
12
Views
268
  • Introductory Physics Homework Help
Replies
5
Views
280
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
979
  • Introductory Physics Homework Help
Replies
1
Views
808
Back
Top