If a positive force the particle will be repelled, if a positive force the particles will be attracted
Use of electric force constant - K
Inverse square law - as the objects get closer the force becomes stronger at an exponential rate
Unlike gravity, elecric force can be positive and negative
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Electric Field Strength
force for each unit of charge
N/C
F=qE
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Radial Fields
Objects with charge at a single point - or can be modeled like that - such as a hollow charge sphere
At any given point field strength = kQ/r^2 - forumla book
Inverse square law
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Electrical Potential Energy
amount of energy requierd to move an object from infinety to a distance r from the particle
attracted particles will have a negative value
Eelec = 0 at infinte distance
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Electrical Potential
the amoutn of electrical potential energy per unit of charge
measured in volts
Velec
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Milikan's Oil drop experiment
found that all charges are some muliple of e
viscous drag - air resistance
for an object falling at terminal velocity all forces must be in equilibrium
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Charge Particles in a Magnetic Field
Force is acting at a right angle to current
F=ILB
F=QVB
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Motion of a charge particle in an electric field
CERN uses magnetic fields to bend particles
circular motion occurs due to a constantly changing current direction
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Particle Accelerators
when a charged is acclerated across a potential difference it gains kinetic energy
KE = qV
when at high speeds you need the gamma factor
Etotal = Erest + Ekinetic = gamma * m *c^2
Linear Accelerators - long evacuate tubes, series of alternating charged electrodes, alternating power supply - as particles are passed through the polarity is changed - electrodes are of increasing length as particle speeds up but AC supply doesn't
Circular Accelerators - bend particles with magnetic fields , radiate synchrotron energy making them less efficent - tighter circle more energy lost.
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