Credit card • Magnetic strip contains iron-based “domains” that can be aligned by a magnetic field • Each magnetic particle in the stripe is a tiny bar magnet about 20-millionths of an inch long • To encode information on to the magnetic strip, the domains can be polarised in either north or south, representing a two-state system much like binary • This process is called “flux reversal” • Magnetic fields: ‣ Flemings left hand rule ‣ F = BIL ‣ When a current flows through a wire a magnetic field is produced around the wire Card reader • The magnetic stripe reader reads the information by detecting the changes in the magnetic field caused by the flux reversals on the card’s magnetic stripe • Screen generated by photons of light ‣ Light is refracted as it changes medium from air to plastic screen back into air again • Spring system in the buttons obeying Hooke’s law: F=ke • On a table - obeying Newton’s Third Law. Card reader exerts forces on table so table exerts equal and opposite (in direction) force on the card reader Question
Credit cardMagnetic strip contains iron-based domains that can
be aligned by a magnetic eldEach magnetic particle in the stripe is
a tiny bar magnet about 20-millionths of an inch longTo encode
information on to the magnetic strip, the domains can be polarised
in either north or south, representing a two-state system much like
binaryThis process is called ux reversalMagnetic elds:!Flemings
left hand rule!F = BIL!When a current ows through a wire a magnetic
eld is produced around the wireCard readerThe magnetic stripe
reader reads the information by detecting the changes in the
magnetic eld caused by the ux reversals on the cards magnetic
stripeScreen generated by photons of light!Light is refracted as it
changes medium from air to plastic screen back into air againSpring
system in the buttons obeying Hookes law: F=keOn a table - obeying
Newtons Third Law. Card reader exerts forces on table so table
exerts equal and opposite (in direction) force on the card
readerQuestion
