# Magnetic Suspension: Calculating I2

• Angie K.
In summary, A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. The current in the second wire is I2.
Angie K.

## Homework Statement

[/B]

A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. What is the current I2 in the second wire? (Enter a positive value if I2 is to the right, negative if it's to the left.)

B=mu0/2pi*(I)/r

## The Attempt at a Solution

I am not sure how to calculate I (current) without knowing the B (magnetic field) .

Can I use the equation from above to figure out the magnetic fields with plugging in different r values? If so, then would I just set them equal to find the other current?

Hello there,

Sort of. You can use your equation to calculate the magnetic field at the position of the lower wire.
Once you have that, you will need another equation to deal with the suspension part.
I expect you can write a force balance for the two forces working on the lower wire ?

BvU said:
Hello there,

Sort of. You can use your equation to calculate the magnetic field at the position of the lower wire.
Once you have that, you will need another equation to deal with the suspension part.
I expect you can write a force balance for the two forces working on the lower wire ?

By force balance, do you mean F=I*L*B ?

That is one force, yes.

Now: you know B (I hope). And what about F ? I2 is to be found, so we must invent something for L. Any ideas ?

Last edited:
Hello BvU once again and Angie
Angie K. said:

## Homework Statement

[/B]

A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. What is the current I2 in the second wire? (Enter a positive value if I2 is to the right, negative if it's to the left.)

B=mu0/2pi*(I)/r

## The Attempt at a Solution

I am not sure how to calculate I (current) without knowing the B (magnetic field) .

Can I use the equation from above to figure out the magnetic fields with plugging in different r values? If so, then would I just set them equal to find the other current?
That red equation is mu0i/2pi r or ## \frac{\mu_0i}{2πr} ##
I think you had a typo there and BvU was pointing it correct.

Hello Raghav !

RG: I did no such thing. And I don't think there was reason to do so.

AK: No reason for alarm: just written a bit awkward, so that a casual reader is easily wrong-footed.

I am sure you meant B = mu0/(2pi) * I / r

As you can see, RG's way of typesetting with LaTeX is much clearer and unambiguous. Worth looking into how to do that ! (see guidelines)

Raghav Gupta

## 1. What is magnetic suspension?

Magnetic suspension is a technology that uses electromagnets to levitate an object, thereby suspending it in mid-air without any physical contact.

## 2. How does magnetic suspension work?

Magnetic suspension works by using the principles of electromagnetism. By running an electric current through a coil, a magnetic field is created, which interacts with the magnetic field of a permanent magnet attached to the object. The interaction between these two fields creates a force that lifts and holds the object in place.

## 3. What is the purpose of calculating I2 in magnetic suspension?

Calculating I2 in magnetic suspension is important because it helps determine the strength of the current needed to generate the desired magnetic force to support the weight of the object. It is a crucial step in designing and controlling the system to achieve stable levitation.

## 4. How is I2 calculated in magnetic suspension?

I2 is calculated by using the formula F = (μ0 * I1 * I2 * N^2) / (2 * π * d). In this formula, μ0 is the permeability of free space, I1 is the current in the primary coil, N is the number of turns in the coil, and d is the distance between the coils. This formula helps determine the required current in the secondary coil to achieve the desired force for magnetic suspension.

## 5. What are the applications of magnetic suspension?

Magnetic suspension has various applications, including high-speed transportation systems, such as Maglev trains, magnetic bearings in machinery and equipment, and even levitating speakers. It is also being explored for potential use in space travel and energy storage systems.

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