Physics with Calculus II

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Physics with Calculus II
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Where weve been

• Mechanics, which includes
• Motion
• Work Power
• Rotational Motion
• Static Equilibrium
• Law of Gravitation
• Fluid Mechanics
• Thermodynamics

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Ch 23 Introduction
Here we begin a study of the electric forces and
the electric field. In daily life we find the
electrical force operating everywhere, because it
is the force that holds most things together. In
particular, the electric force binds atoms
together as in molecules or even as liquids and
solids. The force of gravity is also common, but
it is only capable of holding objects together
when at least one is very massive. On the other
hand, the electrical force acts on the atomic
level in binding electrons to the atomic nucleus
and especially in the formation of molecules, and
is the force most responsible for chemical
reactions.  
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Where were going
Electricity and Magnetism
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Where were going
Ch 23 Electric Fields (23.1) Properties of
electric charges (23.2) Insulators and
conductors (23.3) Coulombs Law (23.4) The
Electric Field ( E ) (23.5) E of continuous
charge distribution (23.6) Electric Field
Lines (23.7) Motion of charges in Electric Field
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(23.1) Properties of electric charges

• Charge is quantized
• Charge is conserved (transfer body to body)
• Unlike charges attract like charges repel
• Force between charges

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(23.2) Insulators and conductors
Conductor readily allows charges to
flow Insulator inhibits charge flow
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(23.3) Coulombs Law
(-) ? attraction () ? repulsion

• Applies ONLY to point charges

More
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(23.3) Coulombs Law, contd
So, one electron has the value
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(23.3) Coulombs Law, contd
This is the charge of the electron AND the proton.
Problem 23.7
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(23.4) The Electric Field ( E )
Where q 0 ? test charge
Compare with Gravitational Field
More
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(23.4) The Electric Field ( E ), contd
Check the units for Electric Field (E)
Problem 23.18
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(23.5) E of continuous charge distribution
And, of course, when q is NOT a point charge.
More
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(23.5) E of continuous charge distribution, contd
Charge distribution for volume
Charge distribution for area
Charge distribution for length
More
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(23.5) E of continuous charge distribution, contd
Problem Ex 23.7, page 724
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(23.6) Electric Field Lines

• Page 727
• The lines begin on a positive charge and end on a
  negative charge.
• Number of lines is proportional to magnitude of
  Q.
• No two field lines may cross.
• Also called Electric Flux lines.

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(23.7) Motion of charges in Electric Field
Problem 23.43
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• The End