X- Rays

Question 1

(2) Suggest why people are not scanned with X-rays in an airport but have X-rays
in a hospital.

Answer 1

(X-rays/they) are harmful
to health (1)
 airport use non-essential/
hospital use essential (1)
 idea that benefits outweigh
risk in hospitals (1)

Question 2

(2) The security people work near the X-ray machine.

Explain how they are protected from the X-rays.

Answer 2

A suggestion linking:
lead casing / shielding (1)
absorbs X-rays (1)

Question 3

(2) Explain what is meant by thermionic emission.

Answer 3

cathode is heated
(1)
 (electrons) given enough
energy
(1)
 (electrons) escape (from
the surface)
(1)