# Bar moving in a magnetic field.

• DannyBoy27
In summary, the conversation discusses a problem with finding the correct equation to solve a physics problem. The speaker mentions trying to use physics instead and deriving the equation. They then share their solution using the equation BLV and finding the velocity to be 0.9375 m/s. They also reference a website for comparison and mention that using BLV can be useful when Maxwell's equations don't work.
DannyBoy27
I have attached a copy of the question I am having issues with, I can't seem to figure out the equation I have to use to solve this. My lecturer did an example of this but for some reason I can't find it anywhere.

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If you cannot figure out the equation - use physics instead, and derive the equation.
What is happening, mechanically and electrically, in the problem?
What sort of law will apply here?

I think I solved the problem. Emf = BLV. And we know that emf will be equal to IR when the current is 0.5A.

0.5 x 9 = 4 x 1.2 x V

Therefore the velocity equals 0.9375 m/s.

Is this correct?

DannyBoy27 said:
I think I solved the problem. Emf = BLV. And we know that emf will be equal to IR when the current is 0.5A.

0.5 x 9 = 4 x 1.2 x V

Therefore the velocity equals 0.9375 m/s.

Is this correct?

Yes.
Good.
Using Blv works even when Maxwell's equations don't!

## 1. What is a "bar moving in a magnetic field?"

A "bar moving in a magnetic field" refers to a scenario in which a metal bar or rod is placed in a magnetic field and is allowed to move or rotate. This can be caused by a variety of factors, such as an external magnetic force or changes in the surrounding magnetic field.

## 2. How does the motion of the bar in a magnetic field occur?

The motion of a bar in a magnetic field is caused by a phenomenon known as electromagnetic induction. This is when a conductor, such as a metal bar, cuts through magnetic field lines and creates an electrical current, which in turn produces a force that causes the bar to move.

## 3. Can the direction of the bar's motion be controlled in a magnetic field?

Yes, the direction of the bar's motion can be controlled by changing the strength or direction of the magnetic field. This can be achieved by using permanent magnets, electromagnets, or by changing the orientation of the bar itself.

## 4. What factors affect the speed of the bar's motion in a magnetic field?

The speed of the bar's motion in a magnetic field depends on several factors, such as the strength of the magnetic field, the size and shape of the bar, and the material of the bar. Additionally, the speed can also be affected by external forces, such as friction or air resistance.

## 5. What are the practical applications of a bar moving in a magnetic field?

The motion of a bar in a magnetic field has various practical applications, including in generators and motors, where it is used to convert mechanical energy into electrical energy and vice versa. It is also commonly used in devices such as speakers, microphones, and accelerometers.

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