(a)(1) State the energy transformations which take place during the operation of a modern x-ray tube.
(ii) Distinguish between hard and soft x-rays.
(iii) State three uses of x-rays.
(iv) Mention one hazard of over-exposure to x-rays in a radiological laboratory, and indicate any two safety precautions.
(b) A possible fusion reaction is (^2_1 H + ^2_1 H to ^3_1H + ^1_1H + Q)
where Q is the energy released as a result of the reaction. If Q = 4.03 MeV, calculate the atomic mass of (^3_1H) in atomic mass units. ((^2_1 H = 2.01410 U; ^1_1H = 1.00783 U; 1U = 931 MeV))
Explanation
(i) Electrical (to) thermal (to) mechanical (kinetic energy) (to) thermal (to) electromagnetic
(ii) Distinction between hard and soft X-rays
| Hard X-rays | Soft x-rays |
|
(i) High (target) voltage (ii) short wavelength (iii) High penetration (iv) produced by high voltage |
Low (target) voltage Long wavelength Low penetration Produced by low voltage |
(iii) Uses:
– Used to detect hidden cracks in materials
– Used to detect alteration to work of art
– To show broken bones in human body
– used in crystallography i.e. to study crystals
– used in diagnosis of ulcer
(iv) Hazards: genetic mutations
– skin burn
– leukemia
– Tissue damage
– Tissue damage
– baldness
– graying
– cataracts
(v) Safety precautions:
use of dosimeter, badges of GM counters
– wearing of lead coats
– Periodic medical counters
– wearing of lead coats
– periodic medical check up
(b)
(^2_1H + ^2_1H to ^3_1H + ^1_1H + Q)
Let atomic mass unit of tritium (^3_1H) be X
2.01410 x 2 x 931 = (x + 1.00783) 931 + 4.03
(frac{3750.254 – 4.03}{931}) = x + 1.00783
4.0238 – 1.0078 = x
3.106 = x