1. Magnetism
Magnetic Force

2. Charged Particles in a Magnetic Field
Constant magnetic fields do not exert force on stationary charges
Moving charges do experience a magnetic force when moving through a magnetic field
Likewise, a stationary charge would experience a magnetic force if the magnetic field changed
Magnetic force is maximized when charges move perpendicularly through a magnetic field and becomes zero if the charge is moving with the magnetic field lines
At our level, we charges will either move perpendicular or parallel to the magnetic field
So values are either at a maximum value or 0

3. Charged Particles in a Magnetic Field
Magnitude of a Magnetic Field
Magnetic Field = magnetic force on a charged particle / (magnitude of charge * speed of charge)
B = Fmagnetic / (q * v)
Magnetic field is measured in Telsas (T) = N/(C*m/s) = N / (A*m) = V*s/m2
Alternative right hand rule can be used to determine the direction of the magnetic force
Extend fingers and thumb at a 90° angle
Magnetic field is in the direction of the fingers
The charge is moving in the direction of the thumb
The force is directed out of the palm if the charge is positive
For negative charges, the force is directed into the palm

4. Alternative Right-Hand Rule: Force on a Moving Charge
Chapter 19
Section 3 Magnetic Force
Alternative Right-Hand Rule: Force on a Moving Charge

5. Charged Particles in a Magnetic Field
A charge moving through a magnetic field follows a circular path
Magnetic force is directed toward the center of the circular path
Changes the direction of the velocity not the magnitude of the velocity

6. Magnetic Force on a Current-Carrying Conductor
Current carrying wire experiences a force when placed in a magnetic field
Force on a Current-Carrying Conductor Perpendicular to a Magnetic Field
Magnitude of magnetic force = (magnitude of magnetic field) * current * (length of conductor within magnetic field)
Fmagnetic = B * I * l
Use the right hand rule to determine the direction of the magnetic force
Thumb in the direction of current
Fingers in the direction of the magnetic field
Positive for out of the palm, negative force into the palm

7. Force on a Current-Carrying Wire in a Magnetic Field
Chapter 19
Section 3 Magnetic Force
Force on a Current-Carrying Wire in a Magnetic Field

8. Magnetic Force on a Current-Carrying Conductor
Two parallel conducting wires exert a force on one another
Forces are perpendicular to the current
When the currents are in the same direction, the forces attract
When the currents are in the opposite direction, the forces repel
Thumb in the direction of current
Fingers coil in the direction of magnetic field

9. Force Between Parallel Conducting Wires
Chapter 19
Section 3 Magnetic Force
Force Between Parallel Conducting Wires

10. Magnetic Force on a Current-Carrying Conductor
Loudspeakers use magnetic force acting on a current carrying wire to produce sound
Sound is converted to a varying electric signal by the microphone
Signal is amplified and sent to the loudspeaker
At the loudspeaker, the varying electrical current causes a varying magnetic force on the coil
Results in vibrations of the attached cone which produce variations in the density of the air in front of it (sound waves)

11. Magnetic Force on a Current-Carrying Conductor

12. Galvanometers
Galvanometer is used in the construction of both ammeters and voltmeters, and therefore multimeters
A torque acts on a current loop in the presence of a magnetic field causing the loop to rotate
Torque is proportional to current
The needle deflects based on the amount of rotation of the coil which is based on the torque which is based on the current
A spring returns the needle to zero in the absence of a current

13. Galvanometers
Galvanometer