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GCE JAN 2011 : AS 2 Waves, Photons and Medical Physics - Revised

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY General Certificate of Education January 2011 Physics assessing Module 2: Waves, Photons and Medical Physics AY121 Assessment Unit AS 2 [AY121] MONDAY 17 JANUARY, AFTERNOON TIME 1 hour 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Answer all questions. Write your answers in the spaces provided in this question paper. For Examiner s use only Question Marks Number 1 INFORMATION FOR CANDIDATES The total mark for this paper is 75. Quality of written communication will be assessed in question 2. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question. Your attention is drawn to the Data and Formulae Sheet which is inside this question paper. You may use an electronic calculator. 2 3 4 5 6 7 8 9 111606 10 Total Marks 6457.05R 1 (a) Mechanical waves can be classified as longitudinal or transverse. Describe the difference between a longitudinal and a transverse wave in terms of the movement of the source that creates the disturbance. Examiner Only Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [2] (b) (i) Light from a lamp is unpolarised. Explain what is meant by unpolarised. ________________________________________________________ _ _________________________________________________________ _______________________________________________________ [1] (ii) Give an example of a wave that cannot be polarised and explain why it cannot be polarised. _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 6457.05R 2 [Turn over 2 Describe an experiment to determine an accurate value for the refractive index of glass using a rectangular glass block. Your answer should include: l a diagram of the apparatus used, l the measurements needed and the instruments used to take them, l how the results are processed to obtain an accurate value for the refractive index of glass. Examiner Only Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [6] Quality of written communication 6457.05R [2] 3 [Turn over 3 When an object is placed 32 cm in front of a converging lens, a virtual image is formed. The image is 2.7 times larger than the object. This is the magnification of the lens which is defined by Equation 3.1 v Magnification = u Examiner Only Marks Remark Equation 3.1 (a) State the defect of vision that this lens could be used to correct in the human eye. ___________________________________________________________ [1] (b) (i) Calculate the power of the lens and state the units of power. Power = ______________ Units of power = ______________ [4] (ii) A person s near point when using this lens is 25 cm from the eye. What distance from the eye is the person s near point when unaided by this lens? Distance to near point = ______________ cm 6457.05R 4 [2] [Turn over 4 Fig. 4.1 shows a loudspeaker mounted near the open end of a tube of length 1.40 m. The loudspeaker is connected to a variable frequency a.c. supply. The frequency of the supply is gradually increased. The sound heard becomes very loud at several distinct frequencies. Examiner Only Marks Remark 1.40 m Signal Generator variable frequency a.c. supply Fig. 4.1. (a) (i) Describe how the standing waves that cause the loud sounds are formed. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (ii) One such loud sound is heard when the frequency is 304 Hz. The speed of sound in air is 340 m s 1. Calculate the wavelength of the sound wave. Wavelength = ________________ m (iii) On Fig. 4.1 sketch the standing wave formed in the tube at frequency 304 Hz. [1] [2] (b) The air in the tube is replaced with helium gas, in which the speed of sound is 965 m s 1. Calculate the minimum frequency of sound that would be required to produce a standing wave in the same tube. Frequency = ________________ Hz 6457.05R [2] 5 [Turn over 5 (a) Laser light is monochromatic. What is meant by monochromatic? Examiner Only Marks Remark _____________________________________________________________ ___________________________________________________________ [1] (b) Fig. 5.1 is a sketch of an arrangement used to measure the wavelength of light from a laser. (Not to scale) Laser Double Slit Screen Fig. 5.1 (i) Describe the pattern that will be seen on the screen in Fig. 5.1. _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 6457.05R 6 [Turn over (ii) The distance from the slits to the screen is 2.80 m. The centres of the slits are 0.24 mm apart. If the distance between the position of one maximum intensity and the next is 7.4 mm, calculate the wavelength of the laser light. Give your answer in nm. Wavelength = ________________ nm Examiner Only Marks Remark [3] (iii) State two ways in which the arrangement could be changed, using the same laser, so that the distance between positions of maximum intensity seen on the screen would be increased. _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 6457.05R 7 [Turn over 6 Fig. 6.1 shows the intensity response with frequency of a human ear. It is used as a measure of perceived loudness which matches the response of the human ear. Examiner Only Marks Remark 120 e thr Intensity level/dB 100 sh 80 ol d of 60 he ari ng 40 20 not detected detected 0 20 40 1 10 100 1000 10000 100000 Frequency/Hz Fig. 6.1 (a) State the main feature of the scale which allows it to match the response of the ear. ___________________________________________________________ [1] (b) Dogs typically have a range of hearing from approximately 20 Hz to 50 kHz. (i) State one similarity and one difference between the frequency range of a dog and a human. Similarity: _________________________________________________________ Difference: _______________________________________________________ [2] 6457.05R 8 [Turn over (ii) Using the intensity level/dB scale for a human ear, the intensity level corresponding to the threshold of hearing of a dog is 20 dB. Dogs ears are most sensitive at a frequency of 5000 Hz. On the axes of Fig. 6.1, sketch a graph of the intensity response with frequency of a dog s ear. The curve should have a similar shape to that of the human ear in Fig. 6.1. [2] Examiner Only Marks Remark (iii) Describe and explain the difference in how a sound of frequency 5000 Hz would be perceived by a human and a dog. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 6457.05R 9 [Turn over 7 (a) The main components of an MRI scanner are the scanner magnet, field gradient coils, rf transmitter, rf receiver and computer. Examiner Only Marks Remark Describe briefly the function of the components listed below. Field gradient coils _____________________________________________________________ _____________________________________________________________ Computer _____________________________________________________________ ___________________________________________________________ [2] (b) Describe how the magnetic field of the scanner magnet is created. Explain how recent advances in technology have vastly reduced the cost of producing this magnetic field. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [3] (c) Outline three advantages of MRI compared to CT scanning. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [3] 6457.05R 1 0 [Turn over 8 A UV (ultraviolet) lamp is shone onto a magnesium surface. Examiner Only Marks Remark (a) (i) Show that, for UV light of wavelength 290 nm, the energy of each photon is 6.86 10 19J. [2] (ii) The magnesium surface has an area of 1.6 10 4 m2. The energy delivered to each square metre every second is 0.034 J. Calculate the number of photons that fall onto the surface each second. Number of photons = ________________ s 1 [3] (b) The frequency of the UV light remains constant and the energy of the incident photons is greater than the work function of the magnesium. (i) State and explain the effect of increasing the intensity of the radiation on the rate of emission of photoelectrons from the magnesium surface. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] (ii) State the effect of increasing the intensity of the radiation on the kinetic energy of the emitted photoelectrons from the magnesium surface. _________________________________________________________ _________________________________________________________ _______________________________________________________ [1] 6457.05R 1 1 [Turn over 9 Energy levels in atoms are described as being quantised. Examiner Only Marks Remark (a) State the meaning of the word quantised. ___________________________________________________________ [1] (b) When electromagnetic radiation passes through hydrogen gas, some frequencies of radiation are absorbed. Fig. 9.1 is a graph showing how the intensity of light transmitted through a sample of hydrogen gas depends on the frequency of the light. Transmitted intensity 6.05 6.10 6.15 Frequency 1014/Hz 6.20 Fig. 9.1 (i) Calculate the energy of the photons associated with the maximum absorption shown in Fig. 9.1. Energy of photons = ________________ J 6457.05R 1 2 [2] [Turn over (ii) Fig. 9.2 shows part of the energy level diagram for hydrogen. Draw an arrow on Fig. 9.2 to show the electron transition that occurs if the electron absorbs a photon of the energy calculated in (b)(i). Examiner Only Marks Remark 0.85 eV 1.50 eV 3.39 eV 13.6 eV Fig. 9.2 [3] (c) The term population inversion can be used in reference to the energy levels of electrons in atoms that emit laser light. Explain what the term population inversion means. _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [2] 6457.05R 1 3 [Turn over 10 Matter is described as having wave particle duality. Examiner Only Marks Remark (a) Explain what this means and outline experimental evidence that confirms that matter has wave properties. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [3] (b) (i) Describe how the de Broglie formula links the particle and the wave nature of matter together. _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] (ii) Calculate the de Broglie wavelength for an electron travelling at 8% of the speed of light. de Broglie wavelength = _____________ m 6457.05R 1 4 [3] [Turn over THIS IS THE END OF THE QUESTION PAPER Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. 111606R GCE (AS) Physics Data and Formulae Sheet Values of constants speed of light in a vacuum c = 3.00 108 m s 1 elementary charge e = 1.60 10 19 C the Planck constant h = 6.63 10 34 J s mass of electron me = 9.11 10 31 kg mass of proton mp = 1.67 10 27 kg acceleration of free fall on the Earth s surface g = 9.81 m s 2 electron volt 1 eV = 1.60 10 19 J Useful formulae The following equations may be useful in answering some of the questions in the examination: Mechanics Conservation of energy 1 mv 2 1 mu 2 = Fs 2 2 Hooke s Law F = kx (spring constant k) Sound intensity level/dB = 10 lg10 Two-source interference = for a constant force Sound Waves I I0 ay d Light Lens formula Magnification 111 += uvf v m = u Electricity Terminal potential difference Potential divider V = E Ir (E.m.f. E; Internal Resistance r) RV Vout = 1 in R1 + R2 Particles and photons de Broglie equation = h p AY111INS 6456.02 111605

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Additional Info : Gce Physics January 2011 Assessment Unit AS 2, Module 2: Waves, Photons and Medical Physics - Revised
Tags : General Certificate of Education, A Level and AS Level, uk, council for the curriculum examinations and assessment, gce exam papers, gce a level and as level exam papers , gce past questions and answer, gce past question papers, ccea gce past papers, gce ccea past papers

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