Copyright © 2007 Pearson Education, Inc. publishing as Addison-Wesley Goals for Chapter 18 To calculate electrical potential energy. To define potential

Copyright © 2007 Pearson Education, Inc. publishing as Addison-Wesley

Goals for Chapter 18 • To calculate electrical potential energy.

• To define potential.

• To study equipotential surfaces

• To review Millikan’s oil drop experiment.

• To examine capacitors.

• To determine electrical field energy


Electrical and gravitational forces - Figures 18.1-18.2• The forces are similar and conservative.


Work and energy changes - Figures 18.3• Work is done on the charge by the field.


Parallel plates and energy conservation – Example 18.2• See the worked example on page 588 and Figure 18.8.


Potential of point and plate charges – Examples 18.3,4• Refer to figures 18.9 and 18.10 with worked examples on pages 589-91.


The equipotential map around charges – Figure 18.11

•Around an charge or arrangement of charges regions of equal potential may be drawn as equal-potential lines.


Equipotential lines may not cross – Figure 18.12

• Considering conduction and geometry one may prove why the lines do not cross.

• Refer to page 592 in your text.


Robert Millikan and electronic charge – Figure 18.16

He suspended charged oil drops of various masses between the parallel plates of a capacitor. His determination found many different multiple of *the same number*. The number was the charge of a single electron, 1.60217653(14)x10-19C.


Energetics of a single electron – Figure 18.17

One electron suspended in a 1V field allows the definition of an energy equivalence.

1eV = 1.602x10-19J


The capacitor – Figure 18.18

Devices may be constructed which separate two conductors of various sizes with materials of various conductance.


The symbol and units of capacitance – Figure 18.19

• Refer to pages 596 – 598 in your text.

• Define the Farad and follow worked examples 18.6 and 18.7.


Capacitors are often joined – Figures 18.21

• Like resistors, capacitors may be combined sequentially (in series).


Capacitors are often joined II – Figures 18.22

• Like resistors, capacitors may be combined in simultaneous fashion (in parallel).


Capacitors store energy – Example 18.9

• This is the whine you can hear while an electronic flash charges.

•Refer to the worked example on pages 602-603.


What is between the conductors? – Figures 18.26,27• As we stated on an earlier slide, the amount of charge that may be stored in a capacitor depends in part on the “filler”.


Capacitors with different dialectrics – Figure 18.28

• Select the dialelectric from table 18.1.


Calculation with a specific dialectric – Example 18.10

Refer to the worked problem on page 605 and figure 18.29.

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Copyright © 2007 Pearson Education, Inc. publishing as Addison-Wesley Goals for Chapter 18 To calculate electrical potential energy. To define potential