Loading in 5 sec....

Chapter 27 Sources of Magnetic FieldPowerPoint Presentation

Chapter 27 Sources of Magnetic Field

- 54 Views
- Uploaded on
- Presentation posted in: General

Chapter 27 Sources of Magnetic Field

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Chapter 27Sources of Magnetic Field

- The Biot-Savart Law
- Gauss’s Law for Magnetism
- Ampere’s Law

A point charge produces an electric field.

When the charge moves it produces a

magnetic field, B:

m0 is the magnetic

constant:

As drawn, the field

is into the page

Example:

Compute field at

point P, due to particle

moving along z axis

Example:

When the expression for B is extended

to a current element, Idl, we get the

Biot-Savart law:

The magnetic field

at a given point P1 is

the sum of the field from each element

P

The magnetic field due to an infinitely long

current-carrying wire can be computed

from the Biot-Savart law. The magnitude of

the magnetic field is:

Recall that the force on a

current-carrying wire in

a magnetic field is

Therefore, two parallel wires,

with currents I1 and I2 exert

a magnetic force on each

other. The force on wire 2 is:

Just as we did for electric fields, we

can define, for a magnetic

field, a flux in a similar

way:

But there is a profound difference

between the two kinds of flux…

Isolated positive and negative electric

charges exist. However, no one has ever

found an isolated magnetic north or south

pole, that is, no one has ever found a

magnetic monopole

Consequently, for any closed surface the

magnetic flux into the surface is exactly

equal to the flux out of the surface

This yields Gauss’s law for magnetism

Unfortunately, however, because this law

does not relate the magnetic field to its

source it is not useful for computing

magnetic fields. But there is a law that is…

I

If one sums the dot product around

a closed loop that encircles a steady current

I then Ampere’s law holds:

That law can be used to compute magnetic fields, given a problem with sufficient symmetry