# Calculate Solenoid Self Force Pressure w/ Corrected B Field

• B
• RingNebula57
In summary: However, I have seen that this is also the value that is used in other cases in which we have self-forces. For example, when we have a beam that is subjected to a torque due to its own weight. Do you have any more information on this?In summary, the equation for calculating the pressure experienced by the surface of a long straight solenoid with ##n## turns per unit length and current ##I## is B=μ0nI. However, this equation can also be used to calculate the pressure experienced by the surface of a solenoid with ends that are not in the center of the solenoid, due to the fact that the self-force of the solenoid at those points is excluded
RingNebula57
Hello everyone! I found in my textbook that in order to calculate the pressure experienced by the surface of a long straight solenoid with ##n## turns per unit length and current ##I## we don't use the typical magnetic field ##B=\mu_0nI## on a loop of the coil , but a corrected magnetic field ##B=\frac{\mu_onI}{2}## which excludes the contribution or "self force" of the loop. How can I prove this formula? (to calculate the pressure is not a problem if I know the formula for ##B##). Furthermore, I saw that this factor ##"\frac{1}{2}"## is used in other cases also in which we have self-forces.

RingNebula57 said:
we don't use the typical magnetic field 1) B=μ0nIB=\mu_0nI on a loop of the coil , but a corrected magnetic field 2) B=μonI2B=\frac{\mu_onI}{2} which excludes the contribution or "self force" of the loop. How can I prove this formula?
( my insertion )

1) is used for calculation of B in the center of an infinit long solenoid. So the solenoid is symmetrical around this center. The resulting B-value is a sum of the contributions from the left/right parts of the solenoid.

2) is used at the ends of the solenoid, because here only the solenoid to the left ( or to the right ) is contributing the B-value at this point. Thus the factor "½".

Hesch said:
( my insertion )

1) is used for calculation of B in the center of an infinit long solenoid. So the solenoid is symmetrical around this center. The resulting B-value is a sum of the contributions from the left/right parts of the solenoid.

2) is used at the ends of the solenoid, because here only the solenoid to the left ( or to the right ) is contributing the B-value at this point. Thus the factor "½".
I am aware of the problem that you solved, but this is not my point. What I am trying to say is that we have an infinitely long solenoid and we try to calculate the tensile force acting on one of its loops ( we can assume that the loop is in the middle) due to the magnetic field of the solenoid. But when we try to do this we have to substract the contribution of the loop itself. And after substracting that we obtain ##B=\frac{\mu_onI}{2}##.

## What is a solenoid?

A solenoid is a coil of wire that produces a magnetic field when an electric current is passed through it. It is often used to convert electrical energy into mechanical energy.

## What is self force pressure in a solenoid?

Self force pressure in a solenoid refers to the force that the magnetic field exerts on the wire itself. This force is caused by the interaction between the magnetic field and the electric current passing through the wire.

## What is the corrected B field in a solenoid?

The corrected B field in a solenoid takes into account any distortions or imperfections in the magnetic field. It is calculated by using the equation Bc = B0(1+k), where B0 is the ideal magnetic field and k is the correction factor.

## How do you calculate solenoid self force pressure with corrected B field?

To calculate solenoid self force pressure with corrected B field, you will need to know the length of the solenoid, the electric current passing through it, and the corrected B field. Then, you can use the formula P = (μ0/2)I^2(Bc^2), where μ0 is the permeability of free space and I is the electric current.

## Why is it important to calculate solenoid self force pressure with corrected B field?

Calculating solenoid self force pressure with corrected B field is important because it provides a more accurate measurement of the force exerted on the wire. Without taking into account any distortions in the magnetic field, the calculated force may be inaccurate and could potentially lead to incorrect conclusions or designs.

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