(a) (i) Explain why x-rays can be used to produce photographs of fractures in bones. (ii) List four uses of x-rays other than in medicine. (b) State the energy transformations which takes place during the operation of an x-ray tube. (c) (i) Explain three named dangers to which human beings may be exposed when subjected to large doses of x-rays. (ii) State two precautions that must be taken by persons working with x-rays. (d) In an x-ray tube, an electron is accelerated from rest towards a tungsten target biased at a potential of 33 kV. Calculate, for the electron, the (i) kinetic energy; (ii) velocity. [h = 6.6 x 10\(^{-14}\) Js; Me = 9.1 x10\(^{-31}\) kg; c = 3.0 x 10\(^4\) ms\(^{-1}\); e = 1.6 x 10\(^{-19}\) C.]
Explanation
(a)(i) X-rays can produce photographs of fractures in bones; it can pass through fractures but cannot penetrate bones. (ii) Uses of x-ray other than in medicine: —detection of cracks in metallic products —detection of alternations in art works —detection of fake gems —examination of bags and luggage —identification of chemical elements and their isotopes. (b) The energy transformations: Electrical energy —> Heat energy —> Kinetic energy —> Electromagnetic energy —> X-rays and Heat energy.
(c)(i) Dangers of over exposure to x-rays are: — Cell mutation, i.e. change in cell genetic codes. — Leukaemia: the destruction of living cells, tissues and organs. — Skins harm, causes skin burn and tanning.
(ii) A person working on x-rays should take the following precautions: — wear lead protective coats — wear dosimeter — wear protective goggles — go for routine regular medical check-up.
(d)(i) K.E. = eV = 1.6x10\(^{-19}\) x 33 x 10\(^3\) = 5.28 x 10\(^{-15}\)J V = \(\sqrt{\frac{2K.E}{m}} = \sqrt{\frac{2 \times 5.28 \times 10^{-15}}{9.1 \times 10^{-31}}}\)
