Standard Grade Physics Health Physics Ink Exercise G1 1. Sounds can travel through : A a vacuum B solids only C liquids only D gases only E solids, liquids and gases 2. A doctor uses a stethoscope like the one shown in the diagram to listen to the sounds of a patient s heart. (a) Explain how the stethoscope acts as a hearing aid for the doctor. Your explanation must give the purpose of each of the parts labelled in the diagram. (b) Why is it important that the bell makes firm contact with the patient s body (KU3) 3. The table below gives sound levels from different sources of sound. Source of sound Sound level (db) 1 metre from a disco loudspeaker 120 5 metres from a pneumatic drill 100 beside a busy motorway 90 inside the cab of a tractor 90 inside a busy supermarket 70 inside a busy office 60 normal conversation 50 When one source of sound is twice as loud as another, the sound level increases by 10 db. (a) Which of the above sources of sound is twice as loud as the level inside a busy office? (b) When working in very noisy surrounding, what precaution should a person take to guard against hearing damage?
4. (a) Information on two types of thermometer, P and Q, is given below. (i) Which thermometer would be better for measuring the temperature of melting ice? Explain your answer. (ii) Which thermometer would be better for measuring a patient s body temperature? Explain your answer. (b) Describe how body temperature is measured using a clinical thermometer. (c) A doctor measures a patient s body temperature as 39 degrees Celsius. Explain how this measurement assists the doctor in making a diagnosis. TOTAL 15
Standard Grade Physics Health Physics Ink Exercise G2 1. Which of the following shows the correct path of a ray of light passing through air and into a block of glass? 2. (a) Describe an experiment which would allow you to measure the focal length of a convex lens. If you wish, you may draw a diagram to illustrate your answer. (KU3) (b) Andrew has an eye defect. He can see clearly an object which is very close to his eye but distant objects appear blurred. (i) What name is given to this eye defect? (ii) State the type of spectacle lens which would allow Andrew to see distant objects clearly. 3. A pupil looks at a sheet of paper which has the letter F drawn on it as shown below. F Draw the image of the letter which would be formed on the pupil s retina. 4. Different types of radiation are used in the detection and treatment of illnesses and injuries. Four of these radiations are : infrared laser light ultraviolet X-rays Which of the above radiations is used for each of the following? (a) In optical surgery to repair small tears in the retina. (b) To treat a skin condition such as acne or eczema. (c) To detect a broken bone in an arm. (PS3)
5. A pupil uses a Geiger-Muller tube and a counter to measure the activity of the background radiation in the laboratory. The counter is switched on for a certain time and a count is recorded. The pupil records the time on a stopclock. The readings obtained are shown on the diagram below. Calculate the activity of the background radiation. 6. State two safety precautions which are necessary when working with a radioactive substance. 7. Martin was in an accident and breaks a bone. (a) To find the position of the break a doctor could use : (A) ultraviolet rays ; (B) X-rays; (C) gamma rays. (i) Which one of the above should the doctor use? (ii) Explain why one of the other rays would not have been suitable. (b) As a result of his injuries, Martin will have to spend a lot of time on his back unable to raise his head. His classmates have designed a pair of special spectacles using triangular glass prisms instead of lenses. One of these prisms is shown below. (i) Copy and complete the diagram to show clearly the effect of the prism on the light and how the light gets to Martin s eye from objects in the room. (ii) What name is given to the effect which the prism has on light? TOTAL 20
Standard Grade Physics Health Physics Ink Exercise C1 1. Ultrasound is used to obtain information about the growth of unborn babies. Ultrasound of frequency 6.0 MHz is transmitted through the mother s body at a speed of 1500 m/s. (a) What is the wavelength of the ultrasound in the mother s body? (b) Why is ultrasound, rather than X-rays, used to obtain information about the unborn baby? 2. During a game, a player injures a knee. An X-ray is taken to check whether the leg has been broken, Ultrasound is used to determine if any fluid has formed in the knee. Figure 1 shows the position of the X-ray transmitter and figure 2 the position of the ultrasound transmitter and receiver in front of the knee. (a) (i) Copy figure 1 and indicate where the receiver for the X-rays should be placed. (ii) State why the ultrasound transmitter and receiver are on the same side of the knee as shown in figure 2. (iii) It is decided to treat the knee injury using ultrasound to speed the healing process. The ultrasound used in the treatment has a power of 8W. The energy to be delivered to the site of the injury is 2400J at each treatment. How many minutes should each treatment last? (b) Read the following passage. The limit of human hearing is 20kHz but other animals, such as bats and dolphins, make use of sound in the 30 100 khz range. Sound above the range of human hearing is called ultrasound. Ultrasound behaves in a similar manner to audible sound, having a speed of 340 m/s in air, a speed of 1500 m/s in soft tissue and a speed of 4100 m/s in bone. Ultrasound is used not only to diagnose the cause of injury but also to help in the healing of injuries. When used in the healing process absorption of ultrasound takes place. (i) State the lowest frequency of ultrasound. (ii) What is the speed of ultrasound in soft tissue? (iii) State whether energy is absorbed or reflected when ultrasound is used to help the healing process.
3. Karen is tidying the reading spectacles on display in a store. The spectacles on the display are labelled 4.0 D, 3.25 D, 2.75 D and 2.5 D. She notices that the label is missing from one pair. Karen is asked to label correctly this pair of spectacles. She uses one of the spectacle lenses to focus a sharp image of a far-away window on to a piece of paper as shown below. The distance between the lens and the paper is 40 cm. Which label should Karen attach to the spectacles? You must show clearly your working which leads you to your answer. 4. The diagram below shows rays of light from a distant object entering the eye of a short-sighted person. Draw a diagram to show how a lens would correct the problem. (KU3) 5. A health physicist is developing a system for measuring temperatures inside the body. A thermocouple is inserted through a tube beside the optical fibres of an endoscope. The endoscope allows the doctor to see where the thermocouple is being positioned. The endoscope consists of two fibre bundles and a cold light source. (a) Explain the purpose of each of the two bundles of fibre (P and Q) in the endoscope. (b) What is meant by a cold light source? (c) Explain whether a filament lamp or a discharge lamp would be more suitable for the light source of the endoscope. TOTAL 20
Standard Grade Physics Health Physics Ink Exercise C2 1. (a) X-ray machines, as shown in figure 1, are used to destroy cancerous tissue in the body of a patient. The X-rays produced by the machine reach the patient from different directions by rotating the machine around the patient s body. In this treatment, the X-rays are not fired continuously in one direction. The different paths of the X-rays through the patient s body are shown in figure 2. (i) Explain why rotating the X-ray machine provides a safer way of ensuring that the cancerous tissue receives the maximum dose. (ii) Why is it important that the patient keeps still during the treatment? (b) After using the X-ray machine, an optical fibre is used to view the tissue inside the patient s body. Figure 3 shows the path of the ray of light as it passes along part of the optical fibre. (i) Which of the angles θ 1, θ 2, θ 3 and θ 4, marked on the diagram, is an angle of incidence? (ii) What name is give to the dotted line NP? 2. The table below gives information about the wavelength and output power of some types of laser. Type of laser Wavelength (m) Output power (W) Excimer 3.2 x 10-7 20.0 Argon 4.9 x 10-7 2.0 Dye 5.5 x 10-7 0.5 Helium-neon 6.3 x 10-7 0.005 The visible spectrum has wavelengths ranging from 4.0 x 10-7 m to 7.0 x 10-7 m. (a) Which laser emits infrared radiation? (b) Name one medical use of infrared radiation. (c) Calculate the frequency of light from the helium neon laser. (PS3)
3. (a) A hospital uses radioactive Technetium in the diagnosis of tumours. The Technetium is injected into the patient. The label on a sample which is delivered to the hospital is shown below. (i) What is meant by the term half-life? (ii) Why is a sample with a short half-life used in diagnosis? (iii) If the sample of Technetium is not used, the hospital is allowed to dispose of it. This is permitted once its activity has fallen below 75 MBq. Show, by calculation, the date and time when the sample will be ready for disposal. (b) The effect of radiation absorbed by living materials depends on a number of factors. Name two of the factors. (PS3) (c) Members of the hospital staff wear film badges to monitor any radiation to which they may become exposed. The film is contained in a plastic holder with windows of different materials as shown in the diagram. The whole badge is protected from light. (i) (ii) Copy the diagram and shade the window or windows where the film will be affected if the wearer is accidentally exposed to the radiation from the Technetium source. Describe how the badge is used to indicate how much radiation has been received. TOTAL 19