1. Chapter 21: Electromagnetic Induction
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2. Goals for Chapter 21
To overview electromagnetic induction and Faraday's law.
To observe examples of Lenz's law.
To study motional electromotive force.
To understand eddy currents.
To study and calculate mutual and self-inductance.
To understand and calculate the action of transformers.
To study and calculate magnetic field energy.
To study R-L and L-C circuits.
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3. Does the Field Induce a Current or Not? – Figure 21.1
In each situation, discuss why a current would be produced or not.
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4. Investigating Induced Currents – Figure 21.2
Changes in the magnetic field or the coil will be detected on the multimeter.
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5. Magnetic Flux Through an Area – Figure 21.3
Recall back to Chapter 17 and Gauss's law. See Conceptual Analysis 21.1 and Example 21.1.
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6. Magnetic Flux at Various Orientations – Figure 21.4
The flux depends on angle of the sample surface.
Refer to Conceptual Analysis 21.1 and Example 21.1.
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7. Faraday's Law – Figure 21.7
The induced current is proportional to the time and the field strength.
Refer to Example 21.3, Conceptual Analysis 21.2, and Problem Solving Strategy 21.1 in your text.
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8. You Can Induce emf in a Coil of Wire – Figures 21.9 and 21.10
This progression of ideas regarding the creation of induced emf in moving conductors leads to the simple alternator.
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9. Lenz's Law – Figure 21.15
To derive the direction as well as the magnitude of an induced field, Lenz expanded on Faraday's law. Notice that it follows the right-hand rule.
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10. Force on a Slide Wire Rod – Figure 21.17
The movement of the rod implies a force.
Refer to Example 21.5 in your text.
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11. The Same Principle in an R-C circuit – Figure 21.17
Refer to Example 21.6 in your text.
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12. Motional Electromotive Force – Figures 21.19 and 21.20
Refer to Example 21.7 and Conceptual Analysis 21.3.
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13. Eddy Currents – Figure 21.21
So far, the magnetism we have studied in circuits was well-defined. This organized behavior is the norm in circuits and along wires.
Like the rotating disk in an electric meter outside your home, swirling patterns of induced currents occur at specific regions and allow for a net force to occur.
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14. Eddy Currents – Figure 21.22
Metal detectors depend on the eddy currents that a concealed weapon could produce.
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15. Mutual Inductance
Circulation of powerful currents generate a field in one device that will induce a current in a separate device.
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16. The Tesla Coil – Figure 21.24
Mutual induction is applied to allow two sets of wire turns, one long and one smaller, to transform voltages.
Refer to Examples 21.8 and 21.9 in your text.
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17. Self-Inductance – Figures 21.25 and 21.27
Any circuit which carries a varying current self-induced from its own magnetic field.
Refer to Example in your text.
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18. Transformers Two coils are wound on the same core.
One coil will generate a field in the core which induces a current in the second coil.
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19. Transformers – Figure 21.28 Refer to Example 21.11 in your text.
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20. Energy Associated with an Induced Current
As energy is introduced at a field, energy is stored in an electronic device.
Refer to Example in your text.
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21. The R-L circuit – Figure 21.30
When an inductor is part of a wired circuit, voltages, currents and capacitor charges are a function of time, not constants.
Refer to Example in your text.
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22. The L-C circuit – Figure 21.33
When an inductor is part of a wired circuit with a capacitor, the capacitor charges over time.
Commonly used in radio as a tuner for the induced current from an antenna.
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