1. RAD 254 Chapt 4/5 Electromagnetic Radiation Photons –No mass/charge –Have velocity, frequency, wavelength & amplitude –Follow the “duality theory” –Travel in discrete bundles of energy “Quantum”

2. Velocity is the speed of light –3 X 10 10 cm/sec OR 3 X 10 8 m/sec –Is the smallest quantity of any type e/m/radiation –Have both electric (A/C) and magnetic qualities –Travel as sine waves

3. Units of electromagnetic concerns Amplitude = height of the sine wave Frequency (f) = length of successive points in the sine wave/cm –As frequency goes up, so does energy (energy is DIRECTLY proportional to frequency) As velocity decreases, so does frequency –Velocity = frequency X wavelength V = f X λ

4. Electromagnetic Spectrum Three ranges : visible light, RF, X-ray –All travel the speed of light, but may have differing frequency and wavelength –Visible light is I’d by it’s wavelength, RF by it’s frequency, and x-rays by energy –Radiation can be ionizing or non-ionizing Non-ionizing can be reflected as well as absorbed Ionizing cannot be reflected BUT can be absorbed and/or scattered Absorbed = attenuated –Radiolucent vs. Radiopaque

5. Inverse Square Law Radiation intensity is inversely related to the square of the distance from the source I 1 (D 2 ) 2 I 2 =(D 1 ) 2 DRAW THE PICTURE FILL IN THE KNOWNS/UNKNOWNS SOLVE DO A “QUICK MENTAL CHECK”

6. Planck’s Quantum Equation E = h X f ( e= photon energy, h = Planck’s Constant and f= photon energy in hertz) Planck’s Constant = 6.63 X 10 -34 J/sec (or 4.15 X 10 -15 eVs)

7. Photon Energy Photon energy is directly proportional to its frequency Photon energy increases as wavelength decreases Photon energy increases as kVp increases

8. Electricity & Magnetism The PRIMARY purpose of an x-ray tube is to convert electric energy into ELECTOMAGNETIC RADIATION

9. Laws of electrostatics Unlike charges attract Like charges repel Electrostatic force is DIRECTLY proportional to the product of the charges and the SQARE of the distance between them When objects are electrified, the charges are distributed throughout the object – BUT tend to be greatest at “pointed” spots

10. Electric terms Electrodynamics = study of electron flow in MOTION (current – AMP) Conductors = Matter that CONDUCTS electrical current Insulators – Matter that INHIBITS current flow –Semi-conductor = depending on conditions, can be either Superconductor = like an MRI unit low resistance (niobium/titanium)

11. Electric Terms, con’t Electric Potential = Volt (V) Resistance = Increasing electric resistance (ohm’s) = LESS current flow in amps (A) Ohm’s law = voltage across the total circuit is equal to the CURRENT X the resistance (V= IR) I=current in amps; R= resistance in ohms; V= potential in volts WATT(W) = measurement of electrical power

12. Current Direct Current (DC) electron flow in only one direction Alternating Current (AC) sinusoidal form each way (+ & -) –Magnetism and AC are very closely related (+/- or N-S pole charges) –Magnets are classified according to their origin (natural, permanent, electromagnet)

13. Magnetic Laws Every magnet has TWO poles Like poles repel – unlike poles attract Magnetic charges and lines may be induced –Magnetic lines are ALWAYS closed –Magnetic force and the distance from the magnet are INVERSELY proportional to the square of the distance – BUT the attraction is GREATEST at the POLES rather than the sides of the magnet