USA uses imperial measurements – probably because it is too expensive to convert Britain uses inches and miles for distances Point out that the correct Australian spelling is METRE. USA uses METER
Common examples of these prefixes are Gigalitres – water reservoirs Megalitres – swimming pools Micrometres – measuring cells under the microscope Nanometres – size of large molecules Emphasize the correct use of prefixes – ML and mL are very different μ m – discuss the use of Greek alphabet in scientific work
Using the cards is important to develop this difficult concept of scale Using the smallest sizes on the left will ensure the number line is the same as used in mathematics. Using the largest sizes on the left will allow easier conversions as the decimal point will move in the same direction All students will probably have only been exposed to linear scales before this task. Emphasize this is a logarithmic scale where each item is 10 times bigger than the previous one.
Video at http://www.micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html
You Tube clip of longest fingernails at - http://au.youtube.com/watch?v=8HuKB1drzbg It would take around 24 years to grow nails to 76cm long
Clip can be seen at http://aunet.com.au/stereo_microscope.htm
If you need some light revision, here are some optional research questions, and a fact sheet is provided
Scale & Measurement Module
Scale & Measurement
Module Outcomes <ul><li>Have an understanding of the metric system </li></ul><ul><li>Be able to compare metric sizes and have an understanding of the nanoscale </li></ul><ul><li>Be able to use scientific instruments for measuring small quantities. </li></ul>
The Metric System <ul><li>Based on powers of 10 </li></ul><ul><li>Used by scientists worldwide so there is no confusion </li></ul><ul><li>What countries do not use the metric system? Why not? </li></ul>Give them 0.254 metres and they’ll take 1.14 ! What does this mean?
Scientific Notation <ul><li>Also called standard form </li></ul><ul><li>More convenient than writing numbers with many zeros </li></ul><ul><li>First number is written between 1 and 10 </li></ul><ul><li>Second number indicates how many places the decimal point has been moved </li></ul><ul><li>Easier to work with powers of 10 when multiplying and dividing very large and small numbers. </li></ul>Number Scientific notation 32 000 3.2 x 10 4 0.0000056 5.6 x 10 -6
Activity 2 <ul><li>Sorting By Size </li></ul>Comparison of Size Nanoparticle Marble Earth 260 nm = 0.00000026 m = 2.6 x 10 -7 m 26 mm = 0.026 m = 2.6 x 10 -2 m 2,600 km = 2,600,000 m = 2.6 x 10 6 m Images: Alicia Solario @ stock.xchng, Earth = woodley wonderworks @ flickr
Did You Know? <ul><li>If you stretched a metre to cover the distance from Melbourne to Perth, a nanometre would still only be the size of an aspirin tablet. </li></ul>Watch video on size comparison to get an idea of the size of a nanometre. Watch video-http://www.micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html
Did You Know? <ul><li>The average human fingernail grows about one nanometre per second. </li></ul>You Tube clip of longest fingernails at - http://au.youtube.com/watch?v=8HuKB1drzbg Images courtesy of: Sunshinecity @ flickr So how long did it take for the Guinness World Record holder for the longest nails to get them to 76cm long?
Did You Know? <ul><li>The earth’s continents drift at about 1 nanometre per second. </li></ul>
Did You Know? <ul><li>A typical cell in the human body is around 7,000 to 10,000 nanometres in diameter. </li></ul>Images L to R: National Institute of Health, Wikimedia, Wikimedia Human red blood cells = ~7000 nm Human tissue cells = ~10,000 nm
Did You Know? <ul><li>Viruses, often said to straddle the boundary between living and nonliving objects, can range from about 75 to 100 nanometres wide. </li></ul>Image: Scripps Research Institute Influenza virus 75 - 100 nm
Did You Know? <ul><li>Carbon nanotubes, composed of bonded carbon atoms are 1000 times thinner than an average human hair but can be 200 times stronger than steel! </li></ul>Image: Schwarzm, Wikipedia Each carbon nanotube is ~7 Nanometres in diameter
Did You Know? <ul><li>Scientists have created carbon nanotubes that could be used as tiny hypodermic needles </li></ul><ul><li>They are capable of injecting molecules one at a time </li></ul><ul><li>This sequence shows the creation of a nanotube by an infrared laser tugging on a polymer membrane. The nanotubes are about 1 centimetre long and stable enough to maintain their shape indefinitely. </li></ul>Image: NIST 10 μ m
Experiment 1 Measurement <ul><li>Instruments for measurement </li></ul>How do we measure small things? There are many instruments used by scientists to measure small quantities: • micrometers • Balances • Micropipettes • Microscopes. What are they used for? What units are used? Image: Splarka, Wikimedia
How Do We Visualise Small Things?. <ul><li>… With microscopes </li></ul><ul><li>Different types of microscopes have specific uses: </li></ul><ul><li>Stereo (or binocular) microscopes are used to magnify relatively large items such as insects x20 </li></ul><ul><li>Light (or monocular) microscopes </li></ul><ul><li>Transmission electron microscopes (TEM) </li></ul><ul><li>Scanning electron microscopes (SEM) </li></ul><ul><li>Atomic force microscopes (AFM) </li></ul><ul><li>Synchrotron . </li></ul>Image: chrisbb @ flickr
Stereo Microscopes <ul><li>Stereo (or binocular) microscopes are used to magnify relatively large items such as insects x20 </li></ul><ul><li>This video clip was taken using a stereo microscope with a digital camera/video eyepiece </li></ul><ul><li>The small worm ( size 3mm ) </li></ul><ul><li>was on a flower petal, whilst recording, it bore a hole through the petal and crawled through the hole. </li></ul>Watch video- http://aunet.com.au/stereo_microscope.htm Image: Wikimedia
Experiment 2 Light Microscope <ul><li>Measuring using a Light microscope </li></ul>Requires the specimen to be very thin so light can pass through it: •Used to magnify tissues and whole cells •x400 •Micrometers (_m) are used for measuring •1mm = 1000 _m. Image: David Duncan @ stock.xchng
Transmission Electron Microscope (TEM) Beams of light are passed through a thinly sliced specimen. • Magnify up to a million times • Reveal the detailed structures inside cells • Produce 2D images. Image: University of Melbourne
Scanning Electron Microscope (SEM) A beam of electrons move across a specimen and constructs an image showing details of its surface. • Produces 3D images • For high resolution surface topographical study of mainly biological specimens. Image: University of Melbourne
SEM Images Images: The Bugscope Project, Beckman Institute, University of Illinois at Urbana-Champaign. http://bugscope.beckman.uiuc.edu/ Bee eyeball Edge of mosquito wing Hairs on a fly
Synchrotron A synchrotron is a large machine (about the size of a football field) that accelerates electrons to almost the speed of light. As the electrons are deflected through magnetic fields they create extremely bright light. The light is channelled down beam lines to experimental workstations where it is used for research. It can be used to study the shape of molecules and proteins There is an Australian synchrotron in Melbourne.
Other Ways of Measuring We can also measure things with light… Diffraction of light can be used to determine the size of particles or the size of the spaces between because particles can make light bend (diffract) around them. The colors seen in a spider web are partially due to diffraction . Image: John Haslam @ flickr
Experiment 3 Diffraction <ul><li>Did you know… </li></ul>You can fit 1 billion nanometres in 1 metre So how small is a nanometre? Imagine slicing one hair into 50,000 distinct strands to get a strand one-nanometre thick. Light can be used to determine the size of particles. Particles can make light bend (diffract) around them. In this activity you will determine the diameter of your hair.
Light Basics <ul><li>What is light? </li></ul><ul><li>What is the speed of light? </li></ul><ul><li>What is the natural source of light? </li></ul><ul><li>What is laser light? </li></ul><ul><li>What is a luminous object? </li></ul><ul><li>What is a non-luminous object? </li></ul><ul><li>What is the electromagnetic spectrum? </li></ul><ul><li>What is the wavelength of visible light? </li></ul><ul><li>What is diffraction? </li></ul>
Revision Questions <ul><li>What is a nanometer? </li></ul><ul><li>List 3 objects that are in the nanometre range. </li></ul><ul><li>What is the average diameter of a human hair? </li></ul><ul><li>Why do scientists want to measure and visualise the nanoscale? </li></ul><ul><li>What is the link between the synchrotron and nanotechnology? </li></ul>
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