mag fields

How to produce a magnetic field

Using a permanent magnet

Using an electric current

Right hand rule

Thumb - current

Fingers around pen - direction of mag field

Left hand rule

Thumb force i

Index field

Middle current

Magnetic flux density

strength of a magnetic field in a region , vector quantity

Motor effect

production of a magnetic field when the conductor is perpendicular to the field

Tesla

strength of magnetic flux density that produces a force of 1 newton on a wire of 1m with a current of 1 ampere flowing perpendicularly to the field

Force on a charged particle

field is perpendicular to velocity so force will act on it causing it to take a circular path at a constant speed ( no work done)

Radius of curvature

beam of charged particles take a circular path with no work done , centripetal force provided by magnetic force

Mass spectrometer

Used to detect relative abundances of isotopes in a gas

No resultant force , magnetic = electric

Only ions of a specific velocity can pass in a straight line

Cyclotron

Features

2 hollow semicircular electrodes

Uniform magnetic field perpendicular to the electrode plane

Alternating pd between electrodes

Alternating pd do particles accelerate back and forth n between gap region and gain KE as it repeats . Eventually radious is large and particles leave as high speed/ energy beam

Circular deflection - of particle speeds up its due to the electric field , faster speed = larger radius

Problems - mass increases when near speed of light so frequency would have to change

Synchrotron radiation - circular path so the particle accelerates so it emits photons of radiation