direction of arrows - iis cremonadirection of arrows + intensity of force for test charge distance...
TRANSCRIPT
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Electric Field
Lesson 2 Level 4
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Lets see some electric Fields! Experiment and video
https://www.youtube.com/watch?v=63FnT0W-Hxc
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Direction of Arrows
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Intensity of Force for test charge
Distance is important!!
+ Try this!
A negative source charge (Q) is shown in the diagram below.
This source charge can create an electric field. Various
locations within the field are labeled. For each location, draw an
electric field vector in the appropriate direction with the
appropriate relative magnitude. That is, draw the length of the
E vector long wherever the magnitude is large and short
wherever the magnitude is small.
+ Review!
It is observed that Balloon A is charged
negatively. Balloon B exerts a repulsive
effect upon balloon A. Would the electric
field vector created by balloon B be
directed towards B or away from B?
A. Towards B
B. Away from B
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Density=Intensity of source
+ How to determine Electric field lines
+ How to determine Electric field lines
+ How to determine Electric field lines
+ Try Yourself!
Two negative charges
A positive and negative charge
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+ How can you show unequal
Amounts of charge?
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+ Final important Principles
Electric field lines always extend from a positively charged object to a negatively charged object, from a positively charged object to infinity, or from infinity to a negatively charged object.
Electric field lines never cross each other.
Electric field lines are most dense around objects with the greatest amount of charge.
At locations where electric field lines meet the surface of an object, the lines are perpendicular to the surface.
+ Concept Question
Which of these patterns is incorrect?
+ Concept Question
Consider the electric field lines shown in the diagram below. From the diagram, it is apparent that object A is ____ and object B is ____.
a. +, + b. -, - c. +, - d. -, +
e. insufficient info
+ Problem
Consider the electric field lines drawn at the right
for a configuration of two charges. Several
locations are labeled on the diagram. Rank these
locations in order of the electric field strength -
from smallest to largest.
+ What are the Charges?
+ Conductors
+ Like a point source Charge
+ Faradays Cage- How does it work?
example
+ Concept Question
Suppose that the sphere of a Van de Graaff
generator gathers a charge. Then the motor is
turned off and the sphere is allowed to reach
electrostatic equilibrium. The charge ___.
a. resides both on its surface and throughout its
volume
b. resides mostly inside the sphere and only
emerges outside when touched
c. resides only on the surface of the sphere
+ Shielding
+ Electro magnetic shielding of
the Earth https://www.youtube.com/watch?v=yEYy_nVC4L0
+ Effect of Surface
Curvature
Electric fields are strongest where
curvature is greatest
+ Problem
A diagram of an irregularly shaped charged
conductor is shown at the right. Four locations
along the surface are labeled - A, B, C, and D.
Rank these locations in increasing order of the
strength of their electric field, beginning with the
smallest electric field.
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Lightning!
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Polarization of Static Charge
reacts with earth like rod and paper
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Air is turned into plasma- as a
great conductor- to form a
lightning bolt!
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Step Leaders
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Streamers (lightning hits the
tallest building on Earth)
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Lightning Rods to the rescue!