Download Electric fields ppt File

What are the only two forces your
body has ever experienced???
• GRAVITY
• ELECTRIC
CHARGED PARTICLES IN
ELECTRIC FIELDS
• EXAMPLES
LHC Cern
circumference = 27 km
depth= 100 m
X ray tube
FIELDS
In physics, a field is a region
where a non contact force acts.
e.g. a gravity field
Gravity Field
Gravity force
Force is in the direction of the field
• Electric Fields are created by charged
particles (electrons or protons)
Force
What shape is the electric field
around her head?
Charged wire in oil.
Floating threads show the field
• Field lines are in the same direction
as the force on a positive charge
Force
extension
• Predict the shape of the field around
a proton and an electron
extension
FIELD BETWEEN PARALLEL PLATES
• Predict the shape of the field
between a negative and positive plate.
Platipii have electric field sensors
in their beaks to detect the
electric fields produced by muscles
in their prey
Force on a charge in an Electric
Field
Force on a mass in a Gravity Field is
F  mg
Force on a charge in an Electric Field is
F  qE
Energy Changes in Fields
Gravity Field
Electric Field
d
h
mass m
W  F  d force F
W  mg  h
E  mgh
charge +q
W  F d
W  Eq  d
E  Eqd
force F
Particle Accelerators
Particle Accelerators are designed to
accelerate charged particles to very
high speeds.
Uses range from TVs to huge colliders.
cathode
anode
filament
Kinetic energy gained by the electron is
E  Eqd
LHC Cern
circumference = 27 km
depth= 100 m
Proton Tube
Particle Detector
Voltage
When a charge moves between the
plates, it gains or loses electrical
potential energy.
Voltage
The VOLTAGE is the energy gained (or
lost) by a Coulomb of charge
energy change
voltage 
ch arg e
E
V
q
an easier way to measure electric
field strength……
E
V
q
E  Eqd
Vq  Eqd
V  Ed
excellence question
E  Eqd
V  Ed
20 mm
5000 V
Calculate the electron’s energy gain.
excellence question for 2.7
E  Eqd
V  Ed EK 
1
2
20 mm
5000 V
Calculate the electron’s velocity as it
passes through the hole.
mv
2
X ray tube
105 V
Calculate the speed of the electrons when they hit the target
Cathode Ray Tubes
With switch open…
With switch closed…
The downward force is constant so the
path of the electron is a parabola
Cathode Ray Tube