Transcript AP Chapter 21

AP Chapter 21
• Magnets
• Always a North and South pole
• Like poles repel
• Magnetic Field lines
• Magnetic Field
tesla 1 gauss = 10-4 tesla
F
B
qo ( v sin  )
• the angle is between the velocity and the
magnetic field
• Magnetic Force
• 1) Charge must be moving
• 2) there must be a velocity component
perpendicular to the magnetic field
• Right Hand Rule 1
• Fingers point in the direction of the magnetic
field
• Thumb points towards the velocity
• Palm points towards the force on a positive
charge
• Motion of a charge in Electric Field vs
Magnetic Field
• Since F and d are perpendicular no work is
done by Magnetic Fields
•
x
.
in to paper out of paper
• Mass Spectrophotometry
 er 2  2
m
B
 2V 
• Force on a current in a magnetic field
F  qvB sin 
F  ILB sin 
• Speakers, microphones
• Torque on a current-carrying wire
  FL sin 
  NIAB sin 
• NIA = magnetic moment
• N = # coils A= area L = length in the field
• Magnetic Fields produced by currents
• Long Straight Wire
• μ0 = 4πx10-7 Tm/A
o I
B
2 r
• R.Hand Rule 2
• Thumb in line with I, fingers curled is B
• Loop of wire
BN
o I
2R
• Solenoid
• n = # turns/m
B int .  0nI