Physics

Question 1

frequency vs wavelength

Answer 1

frequency
how many time the wave shape repeats per unit time
- Hz

wavelength
distance over which shape repeats
- metres

Question 2

speed equation

Answer 2

speed =
frequency x wavelength

3x10*8 ms-1

Question 3

photon energy

Answer 3

EM radiation movement of energy
measured in eV

Question 4

basic production of xrays

Answer 4

electrons fired at atoms at very high speeds
on collision, kinetic energy of electrons converted to EM radiation (x-rays and heat)
x-ray photons aimed at subject

Question 5

what is binding energy

Answer 5

additional energy required to exceed electrostatic force

closer electron to nucleus, greater ES force and binding energy [k shell]

energy to move elecrron from inner to outer shell, equals difference in binding energy

Question 6

tungsten K shell = 69.5
tungsten L shell = 10.2

what is the energy required

Answer 6

59.3 keV

Question 7

what type of current does x-ray production require

Answer 7

unidirectional current

Question 8

mains electricity is AC - how do x-ray unit generators modify this

Answer 8

rectification = mimics DC

Question 9

intensity definition

Answer 9

quantity of photon energy passing through a cross sectional area of the beam per unit time

Question 10

inverse square law

Answer 10

intensity of xray beam is inversely proportional to the square of the distance between the xray source and point of measurement

intensity 1/distance*2

doubling distance will quarter dose

Question 11

if pt standing in the xray beam gets dose of 4grays at a distance of 1m from xray source
what is the dose at 4 metres

Answer 11

0.25Gy

doubling distance will quarter the dose

1m = 4gy
2m = 1gy
4m = 0.25gy