Capacitors

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4/7/06 Capacitors Diodes

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Capacitors
Example (Chapter 12, Exercise 9, p. 419) Two
capacitors are identical except that one has a
thinner insulating layer than the other. If the
two capacitors are storing the same amount of
separated electric charge, which one will have
the larger voltage difference between its plates?
Example (Chapter 12, Exercise 11, p.
419) Suppose a battery is transferring (negative)
charges from one plate of a capacitor to the
other. Why does the work that the battery does
in transferring a charge increase slightly with
each transfer?
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• Quantum Physics
• Wave-Particle Duality
• Energy Levels
• Pauli Exclusion Principle

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Energy Levels in a Solid
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Energy Levels in a Solid
Conductor
Insulator
Photoconductor
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Start with good insulator
Semi-conductors and p-n junction
Add small impurity that opens up some space
in the valence band P(ositive)-type or p-type
Add small impurity that add some electrons to
conduction band N(egative)-type or n-type
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Example (Chapter 12, Exercise 5, p. 419) Thermal
energy can shift some of the electrons in a hot
semiconductor from the valence levels to the
conduction levels. What effect do these shifts
have on the semi-conductors ability to conduct
electricity?
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Start with good insulator
Semi-conductors and p-n junction
Add small impurity that opens up some space
in the valence band P(ositive)-type or p-type
Add small impurity that add some electrons to
conduction band N(egative)-type or n-type
Taken from howstuffworks.com http//electronics.ho
wstuffworks.com/led1.htm
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Biasing the Junction