1. Electromagnetic Induction
Chapter 29
Electromagnetic Induction

2. To consider Faraday’s Law To consider Lenz’s Law To study motional emf
Goals for Chapter 29
To consider Faraday’s Law
To consider Lenz’s Law
To study motional emf
To explore induced electric fields
To summarize Maxwell’s equations and see their application to displacement current

3. Introduction
The motion of a magnet can induce current in practical ways. If a credit card has a magnet strip on its back, “swiping” the card can generate tiny currents that send information to cash registers.
A coil of wire and magnets set into motion around each other will generate currents in the wire. A source of mechanical energy can drive the rotation and make a waterfall into an electrical power station.

4. Induced current
Joseph Henry worked in the United States and Michael Faraday worked in England to discern the details of current generated in wire and permanent magnets in motion relative to each other.
See Figure 29.1 below.

5. Knowing the magnetic flux
Regardless of what moves, knowing the magnetic flux around a conducting entity will allow determination of current induced.
See Figure 29.3 at right and Figure 29.4 below.

6. Emf and the current induced in a loop
Follow Example 29.1.
Figure 29.5 illustrates the example.

7. Find the direction of an induced emf
Consult Figure 29.6 and the text on the bottom of page 997 and top of page 998 and solve.

8. Faraday’s Law Follow Problem-Solving Strategy 29.1.
Refer to Example 29.2.
Figure 29.7 illustrates Example 29.2.

9. The search coil, generator example I
Follow Conceptual Example 29.3.
Consider Example 29.4 and Figures 29.8 and 29.9.

10. Generator example II
The example considers a DC generator and back emf in a motor.

11. Generator example III Follow Example 29.6.
Figure illustrates Example 29.6.

12. Work and power in a slidewire generator
Follow Example 29.7.
Figure illustrates Example 29.7.

13. Lenz’s Law
The direction of any magnetic induction effect is such as to oppose the cause of the effect.
Follow Conceptual Example 29.8.
Follow Example 29.9; Figure illustrates the example.

14. A conducting rod moving in a uniform magnetic field
The rod, velocity, and current are mutually perpendicular.
See the direction of the induced current in the circuit below.
Follow Example

15. The Faraday Disk dynamo
Follow Example
Figure illustrates Example

16. Induced electric fields I
The windings of a long solenoid carrying a current I

17. Induced electric fields II
Refer to Figure below.
Follow Example

18. Eddy currents Consider Figure 29.19 at right.
Consider Figure below.

19. Displacement current and Maxwell’s equations
A varying electric field will give rise to a magnetic field.
Explains electromagnetic waves.

20. Superconductivity and the Meissner effect
When cooled below the critical temperature, superconductive materials lose all resistance to electrical current.
Refer to Figures and at right.