Download presentation
Presentation is loading. Please wait.
1
Electro-Magnetic Induction
© D Hoult 2008
2
The Laws of Electro-magnetic Induction
3
Lenz’s Law When e.m.i. occurs, any induced current will flow in such a direction as to
4
Lenz’s Law When e.m.i. occurs, any induced current will flow in such a direction as to oppose the change producing it
5
Lenz’s Law When e.m.i. occurs, any induced current will flow in such a direction as to oppose the change producing it It should be clear that Lenz’s law is an “electro-magnetic version” of
6
Lenz’s Law When e.m.i. occurs, any induced current will flow in such a direction as to oppose the change producing it It should be clear that Lenz’s law is an “electro-magnetic version” of the law of conservation of energy
7
Lenz’s Law Faraday’s Law
When e.m.i. occurs, any induced current will flow in such a direction as to oppose the change producing it Faraday’s Law The induced emf is directly proportional to the
8
Lenz’s Law Faraday’s Law
When e.m.i. occurs, any induced current will flow in such a direction as to oppose the change producing it Faraday’s Law The induced emf is directly proportional to the rate of change of flux linking the conductor
9
The sense of the induced current can be predicted using Fleming’s RIGHT hand rule
10
The sense of the induced current can be predicted using Fleming’s RIGHT hand rule
which is pretty much like Fleming’s left hand rule
11
The sense of the induced current can be predicted using Fleming’s RIGHT hand rule
which is pretty much like Fleming’s left hand rule except, guess what...
12
The sense of the induced current can be predicted using Fleming’s RIGHT hand rule
which is pretty much like Fleming’s left hand rule except, guess what... using the right hand instead of the left hand !
13
ThuMb Motion First finger Field SeCond finger Current
14
Both the laws of e.m.i. can be combined in a single mathematical statement
15
Both the laws of e.m.i. can be combined in a single mathematical statement
Faraday
16
Both the laws of e.m.i. can be combined in a single mathematical statement
Faraday Df E a Dt
17
Both the laws of e.m.i. can be combined in a single mathematical statement
Faraday Df E a Dt Faraday + Lenz
18
Both the laws of e.m.i. can be combined in a single mathematical statement
Faraday Df E a Dt Faraday + Lenz Df E a - Dt
19
Using the S.I. system of units the constant of proportionality is 1 so, if (as is often the case) the conductor is a coil of wire having N turns, we have
20
Using the S.I. system of units the constant of proportionality is 1 so, if (as is often the case) the conductor is a coil of wire having N turns, we have Df E = -N Dt
21
Using the S.I. system of units the constant of proportionality is 1 so, if (as is often the case) the conductor is a coil of wire having N turns, we have Df E = -N Dt This equation is often referred to as Neumann’s Law
22
For a wire moving at 90° to a field with speed v, the induced emf is given by
23
For a wire moving at 90° to a field with speed v, the induced emf is given by E = - B L v
24
E = - B L v
25
Ds E = - B L v = - B L Dt
26
Ds DA E = - B L v = - B L = - B Dt Dt
27
Ds DA Df E = - B L v = - B L = - B = - Dt Dt Dt
28
Ds DA Df E = - B L v = - B L = - B = - Dt Dt Dt This suggests that change of flux linking a conductor and flux cutting by a conductor are equivalent actions
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.