Download presentation

Presentation is loading. Please wait.

Published byDarwin Kimberly Modified over 2 years ago

1
I I

3
Magnetic field similar to a bar magnet For a very long solenoid, the magnetic field can be considered to be confined to the region inside the coils.

4
2a2a z x 2a2a

5
x z a z r x components cancel z >> a a r

6
i At a point along the axis z >> a current loop in xy-plane magnetic dipole moment right hand screw rule

7
H B Diamagnetic material m < 0 (small) B = o (1+ m ) H Permeability = o (1+ m ) =slope of B-H line

8
Ideal magnetic material or paramagnetic material m > 0 (small) B = o r H = H = constant = slope of B-H curve B H

9
L11.5 : Magnetization If H is large or substance strongly magnetic (e.g. ferromagnetic), as H increases, the magnetization M (and hence B) may increase nonlinearly: Measure from the graph So r varies with H. Could also use “differential permeability” High field region where slope decreases is called "saturation" region.

10
L11.6 : Magnetization Hysteresis Ferromagnetic materials also show a “hysteresis” effect, where decreasing the applied magnetic field, or H, doesn’t produce the reverse effect of increasing the field: B r = “remanence” or “residual magnetism” H c = “coercivity”

11
L11.7 Magnetization “hard” magnetic materials: H c is high, area of the loop is large, used for permanent magnets. “soft” magnetic materials: H c is small, area of loop is small, used for transformer cores & electromagnets. Material can be demagnetized by striking or heating it, or go round the hysteresis loop, gradually reducing its size. "Degaussing"

12
L9.1 : Magnetic fields due to currents Magnetic fields are produced by currents. Biot-Savart law Ampere’s law Example: so

13
L9.2 : Magnetic fields due to currents A solenoid: (n is number of turns/length) Therefore(inside)

14
L9.3 : Magnetic fields due to currents Use the Biot-Savart law to derive the magnetic field on the axis of a current loop: and Therefore

15
L9.4 : Magnetic fields due to currents Magnetic field of the Earth

16
L9.5 Magnetic fields due to currents The magnetic field of a magnetic dipole: This magnetic field has the same shape as the electric field of an electric dipole: do the exercise in the Exercise Set. (I , A 0)

18
w t I B - + + + + + + + - - - - - - - - - charge carriers are electrons for copper Right hand rule electrons are deflected down bottom of probe is negative Z X Y

19
w t I B Z X Y

20
M HM H Saturation of M coercivity retentivity (remanence) Saturation of M Area enclosed = energy dissipated in a cycle in reversing the magnetic domains

21
A B C D F J E K H I L I G

Similar presentations

OK

We have looked at the magnetic field from a single loop of wire

We have looked at the magnetic field from a single loop of wire

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on natural disasters in hindi Ppt on air pollution act Ppt on direct and online marketing Make a ppt on election system in india Ppt on bacterial zoonoses Waters view ppt online Ppt on surface water pumps Maths ppt on surface area and volume class 10 Ppt on underground metro rail in india Ppt on itc group of hotels