## Monday, August 5, 2013

### PPT On Magnetic Forces Materials And Inductance

Magnetic Forces Materials And Inductance Presentation Transcript:
1.Magnetic Forces, Materials, & Inductance

2.Magnetic Field
A bar magnet has a magnetic field around it. This field is 3D in nature and often represented by lines LEAVING north and ENTERING south
To define a magnetic field you need to understand the MAGNITUDE and DIRECTION
We sometimes call the magnetic field a B-Field as the letter “B” is the SYMBOL for a magnetic field with the TESLA (T) as the unit.

3.Magnetic Force on a moving charge
If a MOVING CHARGE moves into a magnetic field it will experience a MAGNETIC FORCE. This deflection is 3D in nature.

4.Lorentz Force Equation
The force on a moving particle arising from both Electric and Magnetic fields.
C is the speed of light.

5.Lorentz Force Equation
Electron Orbits in Magnetron.
Proton Paths in cyclotron.
Plasma Characteristics in MHD generator.
Charge particle motion in both combined Electric and Magnetic Fields.

6.Force on a Differential Current Element
Assume two current loops

7.Force on a Differential Current Element

8.Force and Torque on a closed circuit

9.Torque

10.Force and Torque on a closed circuit
If B is uniform on the loop current , then the net force is zero (no displacement)
If B is not uniform, the net force is not always zero
The magnetic field causes a Torque on the loop
This torque will try to make the magnetic field due to the loop current in the same direction of the external magnetic field B

11.Force and Torque on a closed circuit

12.The Nature of Magnetic Materials
Materials have a different behavior in magnetic fields
Accurate description requires quantum theory
However, simple atomic model (central nucleus surrounded by electrons) is enough for us
There are 3 magnetic dipole moments:
1. Moment due to rotation of the electrons
2. Moment due to the spin of the electrons
3. Moment due to the spin of the nucleus

13.We will study 6 types:
Diamagnetic
Paramagnetic
Ferromagnetic
Ferrimagnetic
Anti-ferromagnetic
Super paramagnetic

14.Diamagnetic Materials
Without an external magnetic field, diamagnetic materials have no net magnetic field
With an external magnetic field, they generate a small magnetic field in the opposite direction
The value of this opposite field depends on the external field and the diamagnetic material

15.Atoms have a small net magnetic dipole moment
The random orientation of atoms make the average dipole moment in the material zero
Without an external field, there is no magnetic property