1. KeyWords: ionising radiation, X-rays, evacuated tube, filament, electron gun, thermionic emission, potential difference, amperes, coulombs, inverse square law CAT scans, fluoroscope, P3 topic 2 (i) X-rays and ECGs This topic looks at: X-rays 1.How can you produce an X-ray with greater energy? 2.How can you increase the number of X-rays produced? Label the X ray machine using the terms in the box below Describe how X- rays are produced. (6 marks) Heated cathode, electron beam, X-rays emitted, vacuum, rotating anode What types of electromagnetic radiation are ‘ionising’? Current in X-ray machines is the rate of flow of particles. I = N x q I = current (in amperes), N = number of particles flowing per second, q = charge on each particle ( in coulombs) The charge on an electron is 1.6 x 10 -19 C 1. What is the current when the number of electrons is 8.4 x 10 14 per second? Kinetic energy = ½ mv 2 Kinetic energy = eV What is m in this equation? What is e in this equation? What is v in this equation? What is V in this equation? 1. What is the kinetic energy of an electron when the p.d. is 200kV? 2. If the mass of an electron is 9.11 x 10 -31 kg, then what is the velocity of an electron in question 1.? What is an electron gun? PANIC – Positive Anode, Negative is Cathode

2. KeyWords: inverse square law, CAT scan, fluoroscope, risks, benefits P3 topic 2 (ii) X-rays and ECGs This topic looks at: Using X-rays Describe what a fluoroscope is and what it is used for. 6 mark practice. Evaluate the use of X-rays and CAT scans to diagnose medical problems. (Remember ‘evaluate’ question, need pros, cons and a conclusion – in this case pros are benefits, cons are risks, conclusion – do the risks outweigh the benefits?) Describe what is meant by the inverse square law. Which people should not have CAT scans and why? Describe what happens in a CAT scan Describe why bones show up as white on X rays, but muscles show as dark areas.

3. KeyWords: action potential, electrocardiogram, time period, frequency, pulse oximeter, LED P3 topic 2 (iii) X-rays and ECGs This topic looks at: ECGs and pulse oximetry Frequency, f (hertz Hz) = 1/time period, T (seconds) Each larger square on an ECG is usually 0.2 seconds. Frequency of a heartbeat is usually given in beats per minute, so multiply frequency by 60 to find beats per minute. Describe how electrical signals in the heart muscle cells cause a heartbeat. Include the term ‘action potential’. Describe how the characteristic shape of a normal ECG relates to heart action. Why can the human body conduct electricity? Describe the use of a pacemaker to regulate heart action. Calculate the frequency of the heartbeats in the diagram top left. Assume each square is 0.2 seconds. Normal = Fast = Slow = Irregular = What is an ECG? How does pulse oximetry work and when is it used? Include the words, LED, red and infrared.