Magnetism Magnetic Force

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

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

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

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

Charged Particles in a Magnetic Field

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 force out of the palm, negative force into the palm

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

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

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

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)

Magnetic Force on a Current-Carrying Conductor

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

Galvanometers Galvanometer