(a) State two;
(i) properties of x-rays
(ii) reasons to show that x-rays are waves
(iii) uses of x-rays other than those in medicine;
(iv) hazards of x-rays.
(b) The potential difference between the cathode and target of an x-ray tube is 5.00 x 10\(^4\)V and the current in the tube is 2.00 x 10\(^{-2}\)A. Given that only one percent of the total energy supplied is emitted as x-radiation, determine the ospheric pressure.
(i) maximum frequency of the emitted radiation
(ii) rate at which heat is removed from the target in order to keep it at steady temperature. [Planck's constant, h = 6.63 x 10\(^{-34}\) Js, electronic charge e = 1.60 x 10\(^{-19}\) C]
Verified Correct Answer: .
Physical Principles & Numerical Solution
(a)(i) Properties of X-rays are:;
They (a) penetrates substance
(b) travel in straight lines
(c) are able to ionise gases.
(d) affect photographic plate or paper making them to fogge
(e) undergo reflection, or refraction, or polarization or diffraction etc.
(ii) X-rays are electromagnetic waves with wave properties such as;
- reflection
- refraction
- diffraction
- polarisation
- travel in straight line
- cannot be deflected by magnetic or electric field.
(iii) X - rays (a) used to ionise gases causing them to become conducting.
(b) used in industries to locate fractures in machines and metal castings.
(c) used to analyse crystal structure i.e. crystallography.
(iv) X - rays are hazardous because they
- kill mall organisms
- cause leukaemia can damage riving tissues
- cause genetic mutation
- cause damage to cells of large animals.
(b)(i) hf = eV
f = \(\frac{eV}{h}\)
f = 1% of eV = \(\frac{1 \times 1.60 \times 10^{-17} \times 5.00 \times 10^4}{100 \times 6.63 \times 10^{-34}}\) = 1.207 x 10\(^7\) Hz.
(ii) Times rate at which heat is removed = 99% x I x V
= \(\frac{99}{100}\) x 2.00 x 10\(^{-2}\) x 5.00 x 10\(^4\)
= 990W
Source: Myschool Past Questions Archive (Record #53959)