Units of Instruction

-  Unit 1  -  Electromagnetism

-  Unit 2  -  The X-Ray Machine

-  Unit 3  -  X-Ray Production

-  Unit 4  -  X-Ray Emission

-  Unit 5  -  X-Ray Interaction With Matter

Review:

• The primary function of an x-ray machine is to convert electrical energy into electromagnetic energy.
• Protons and electrons are the two fundamental electric charges.
• Electrostatics involves the study of fixed electric charges.
• Electrification is a process whereby an object has either excess or insufficient electrons.
• The Earth is referred to as "ground" because it serves as a reservoir for stray electric charges.
• Friction, contact and induction are three methods in which an object can become electrified.
• Electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them.
• Coulomb's law describes the magnitude of an electrostatic force.
• 1 coulomb is equal to 6.3 times ten to the eighteenth power.
• Electrodynamics is the study of electrostatic charges in motion.
• Conductors allow for the free flow of electrons  -  copper, water, most metals
• Insulators hinder the flow of electrons  -  glass, dirt, rubber
• Semiconductors act as both conductors and insulators  -  germanium, silicon
• An electric circuit contains three components  -  voltage, amperage and resistance
• Ohm's Law    -     V=IR
• Series circuits  -  all elements connected in a line along the same conductor.
• Parallel circuits  -  elements bridge the circuit rather than lie in a line along the conductor
• Power  =  amperage  x  voltage     P=IV       -or-      Power =  amperage squared  x  resistance
• Power loss in a transformer is via the production of heat.
• Magnetic materials  -  iron, nickel, cobalt
• Unit of magnetic field strength is the tesla (older unit = gauss).   1 T  =  10,000 G
• The Earth's geographical north pole is its south magnetic pole.
• A lodestone is a natural magnet.
• Permeability  -  the ease at which a material can be magnetized
• Retentivity  -  the ability of a material to stay magnetized
• Permeability and retentivity are inversely proportional.
• Nonmagnetic materials  -  unaffected when brought into a magnetic field -  wood, glass, plastic
• Ferromagnetic materials  -  strongly attracted by a magnet  -  iron, nickle, cobalt
• Paramagnetic materials  -  slightly attracted by a magnetic field  -  platinum, aluminum
• Diamagnetic materials  -  weakly repelled by a magnetic field  -  beryllium, bismuth, lead, water
• Series circuits  -  amperage remains the same throughout the circuit, add individual resistors to find the total resistance, add the individual voltages to calculate the total voltage
• Parallel circuits  -  voltage remains the same throughout the circuit, the total resistance is inversely proportional to the sum of the reciprocals of each individual resistance, add individual amperages to find the total amperage
• The circuit must have a closed switch for electricity to flow.
• Electric charges are concentrated on the surfaces of the sharpest curvature.
• If a simple magnet is broken into smaller and smaller pieces, smaller magnets are produced.
• Opposite poles of a magnet attract, like poles of a magnet repel.
• Electrostatic charges are concentrated on the outside of an object
• In ferromagnetic materials, the magnetic dipoles are randomly aligned.  In a magnet, the dipoles are aligned in a single direction.
• The magnetic field exits the north pole of the magnet and reenters into the south pole of the magnet.
• A moving charged particle induces a magnetic field in a plane perpendicular to its motion.
• The unit of power is the watt or horsepower.  1 horsepower is equal to 746 watts.