Magnetic Field of Wire

• Master J
In summary, the question is about the magnetic field inside and outside a long wire with radius R and current I. The Law of Biot & Savart (mu.I/2.pi.r) can be used to find the field a distance r from the wire. Additionally, the current elements on opposite sides of the wire will contribute to the field within the wire, considering their motion.

Master J

A long, current carrying wire has a radius R and current I.
What is the magnetic field inside, and outside the wire?

Now, if it asked what is the field a distance r from the wire, I could simply use the Law of Biot & Savart (mu.I/2.pi.r). I havn't dome electricity in a while and I am stuck on this one.

I am sure its simple, I just need a nudge.

Thanks guys.

Where will the current elements be carried on the wire? And as they are in motion consider the current elements on opposite sides of the wire and what their contribution would be to the field within the wire.

The magnetic field of a long, current-carrying wire can be described by the Biot-Savart law, which states that the magnetic field at a point is proportional to the current, the distance from the wire, and the direction of the current. The formula for the magnetic field inside the wire is given by B = (mu.I/2.pi.r), where mu is the permeability of the medium, I is the current, and r is the distance from the wire.

Inside the wire, the magnetic field will be circular and its strength will decrease as you move further from the center of the wire. Outside the wire, the magnetic field will also be circular, but its strength will decrease much more rapidly. This is because the wire acts as a source of the magnetic field and the strength of the field decreases with distance from the source.

The direction of the magnetic field can be determined using the right-hand rule, where the thumb points in the direction of the current, and the fingers curl in the direction of the magnetic field.

In summary, the magnetic field inside the wire will be circular and will decrease with distance, while outside the wire it will also be circular but will decrease more rapidly. The direction of the magnetic field can be determined using the right-hand rule.

1. What is a magnetic field of wire?

The magnetic field of wire is the region surrounding a wire in which a magnetic force is exerted on other objects or particles due to the flow of electric current through the wire.

2. How is the magnetic field of wire created?

The magnetic field of wire is created by the flow of electric current through the wire. As the electrons move through the wire, they create a circular magnetic field around the wire.

3. What factors affect the strength of the magnetic field of wire?

The strength of the magnetic field of wire is affected by the amount of current flowing through the wire, the distance from the wire, and the type of material the wire is made of.

4. How can the direction of the magnetic field of wire be determined?

The direction of the magnetic field of wire can be determined using the right-hand rule. Point your thumb in the direction of the current flow and your fingers will curl in the direction of the magnetic field.

5. What are some practical applications of the magnetic field of wire?

The magnetic field of wire has various practical applications, such as in electromagnets used in cranes and MRI machines, electric motors, and generators. It is also used in electronic devices like speakers and headphones.