1. X-ray production
Unit 20 strand 1 (P2)

2. X-rays were first discovered in 1895 by the German
physicist William Roentgen, when using a Crookes
tube
He called them ‘x’ rays, ‘x’ for ‘unknown’.

3. The first x-ray
photograph:
Roentgen’s wife
Bertha’s hand

5. X-rays are produced when high-speed electrons hit a metal target. In medical
x-rays this is usually tungsten.
X-rays are electromagnetic radiation of high frequencies (1017-1020 Hz)
Electrons are produced by thermionic emission.
They are accelerated across the vacuum tube towards the positive (anode)
target.
The electrons strike the target and lose about 99% of their energy in low-energy
collisions with the target atoms – this heats up the target. The remainder of the energy
reappears as x-ray radiation.
Overheating is prevented by using a rotating anode and circulating oil. Copper is used
for the anode mountings.