90732 907320 3SUPERVISOR S Level 3 Science, 2012 90732 Describe selected properties and applications of EMR, radioactive decay, sound and ultrasound 9.30 am Wednesday 28 November 2012 Credits: Four Check that the National Student Number (NSN) on your admission slip is the same as the number at the top of this page. You should attempt ALL the questions in this booklet. If you need more space for any answer, use the page(s) provided at the back of this booklet and clearly number the question. Check that this booklet has pages 2 10 in the correct order and that none of these pages is blank. YOU MUST HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THE EXAMINATION. Achievement Criteria Achievement Achievement with Merit Achievement with Excellence Describe selected properties and applications of EMR, radioactive decay, sound and ultrasound. Explain selected properties and applications of EMR, radioactive decay, sound and ultrasound. Overall level of performance Discuss selected properties and applications of EMR, radioactive decay, sound and ultrasound. New Zealand Qualifications Authority, 2012. All rights reserved. No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
2 You are advised to spend 45 minutes answering the questions in this booklet. QUESTION ONE: IRRADIATION OF FOOD Food such as dried herbs and spices can be treated by irradiation using radioactive cobalt-60 to kill any microorganisms present. Cobalt-60 has a half-life of 5.3 years, and decays releasing both a beta particle and gamma radiation. Cobalt-60 is no longer suitable for use when the counts per second (c s 1 ) fall to 100 c s 1. Discuss the use of cobalt-60 in irradiating dried herbs and spices and calculate the useful lifespan of a sample with an initial activity of 144 c s 1. Your answer should include: completion of the decay equation for cobalt-60 a comparison of the properties of beta and gamma radiation how gamma radiation works to kill the micro-organisms without destroying the herbs and spices the useful lifespan of a sample of cobalt-60 with an initial activity of 144 c s 1. B Co Ni + β + D 60 60 27 A C A = B = C = D =
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QUESTION TWO: PHOTOGRAPHIC IMAGING Photographs (images) can be taken using visible light, x-rays, infra-red, gamma rays, ultraviolet radiation or radio waves. These radiations are all found on the spectrum of electromagnetic radiations. 4 For copyright reasons, this resource cannot be reproduced here. http://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/em_spectrum.svg/787px-em_spectrum.svg.png Light waves are commonly used to produce images of objects that are close to the viewer, but radio waves are often used to produce images of very distant objects (such as distant galaxies). For copyright reasons, this resource cannot be reproduced here. Light image Radio image http://upload.wikimedia.org/wikipedia/commons/c/ c2/m87_vla_vlba_radio_astronomy.jpg
5 Compare the properties of visible light waves and radio waves, and discuss the production of images from light and radio waves. Your answer should include: a labelled diagram of an electromagnetic wave showing amplitude and wavelength the properties of visible light and radio waves that allow the production of images the factors that result in the particular waves being more suitable for particular purposes.
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7 This page has been deliberately left blank. The examination continues on the following page.
8 QUESTION THREE: ACOUSTICS Music auditoriums and theatres are designed to ensure that all guests can hear the music or spoken performances well (ie that they have good acoustics). For copyright reasons, this resource cannot be reproduced here. Adapted from David Balker and Sandy Talbett, NCEA L3 Study Guide Science (Auckland: ESA Publications, 2005), p 240. Example of an auditorium For copyright reasons, this resource cannot be reproduced here. http://aiabuffalowny.org/images/design_awards/foit%20albert10a%20fletcher%20hall.jpg Discuss how the properties of sound waves affect the design of an auditorium to ensure good acoustics. Your answer should include: a description of the properties of sound waves: reflection, absorption, loudness, interference how the design of an auditorium uses the properties of sound to ensure good acoustics how the materials used ensure good acoustics.
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10 QUESTION NUMBER Extra paper if required. Write the question number(s) if applicable.
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