90732
3
907320
SUPERVISOR’S USE ONLY
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.
ASSESSOR’S USE ONLY
Achievement
Describe selected properties and
applications of EMR, radioactive
decay, sound and ultrasound.
Achievement Criteria
Achievement with Merit
Explain selected properties and
applications of EMR, radioactive
decay, sound and ultrasound.
Achievement with Excellence
Discuss selected properties and
applications of EMR, radioactive
decay, sound and ultrasound.
Overall level of performance
© 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.
60
27
Co →
60
A
A = ___________
Ni +
B
C
β + D
B = ___________
C = ___________
Science 90732, 2012
D = ___________
ASSESSOR’S
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3
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4
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.
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
Science 90732, 2012
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.
Science 90732, 2012
ASSESSOR’S
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6
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7
This page has been deliberately left blank.
The examination continues on the following page.
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8
QUESTION THREE: ACOUSTICS
ASSESSOR’S
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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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Science 90732, 2012
10
QUESTION
NUMBER
Extra paper if required.
Write the question number(s) if applicable.
Science 90732, 2012
ASSESSOR’S
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90732