Scale & Measurement

Module Outcomes• Have an understanding of the

metric system• Be able to compare metric sizes

and have an understanding of the nanoscale

• Be able to use scientific instruments for measuring small quantities.

The Metric System• Based on powers of 10 • Used by scientists worldwide so there

is no confusion• What countries do not

use the metric system? Why not?

Give them 0.254 metres

and they’ll

take 1.14!

What does this mean?

Scientific Notation• Also called standard form• More convenient than writing numbers with many

zeros• First number is written between 1 and 10• Second number indicates how many places the

decimal point has been moved• Easier to work with powers of 10 when multiplying

and dividing very large and small numbers.

Number Scientific notation

32 000 3.2 x 104

0.0000056 5.6 x 10-6

Activity 1Metric Conversions

Activity 2Sorting By Size

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 106 m

Images: Alicia Solario @ stock.xchng, Earth = woodley wonderworks @ flickr

Did You Know?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.

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?

You Tube clip of longest fingernails at - http://au.youtube.com/watch?v=8HuKB1drzbgImages courtesy of: Sunshinecity @ flickr

The average human fingernail grows about one nanometre per second.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?The earth’s continents drift at about 1 nanometre per second.

Did You Know?A typical cell in the human body is around 7,000 to 10,000 nanometres in diameter.

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? Viruses, often said to

straddle the boundary between living and nonliving objects, can range from about 75 to 100 nanometres wide.

Image: Scripps Research Institute

Influenza virus75 - 100 nm

Did You Know?Carbon nanotubes, composed of bonded carbon atoms are 1000 times thinner than an average human hair but can be 200 times stronger than steel!

Image: Schwarzm, Wikipedia

Each carbon nanotube is ~7Nanometres in diameter

Did You Know?

Image: NIST

• Scientists have created carbon nanotubes that could be used as tiny hypodermic needles

• They are capable of injecting molecules one at a time

• 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.

10μm

Experiment 1 Measurement

Instruments for measurement

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?.

…With microscopes

Different types of microscopes have specific uses:1. Stereo (or binocular) microscopes are used to

magnify relatively large items such as insects x202. Light (or monocular) microscopes3. Transmission electron microscopes (TEM)4. Scanning electron microscopes (SEM)5. Atomic force microscopes (AFM)6. Synchrotron.

Image: chrisbb @ flickr

Stereo Microscopes• Stereo (or binocular) microscopes

are used to magnify relatively large items such as insects x20

• This video clip was taken using a stereo microscope with a digital camera/video eyepieceThe small worm (size 3mm)was on a flower petal, whilst recording, it bore a hole through the petal and crawled through the hole.

Watch video- http://aunet.com.au/stereo_microscope.htmImage: Wikimedia

Experiment 2 Light Microscope

Measuring using a Light microscope

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

TEM Image of Plant Cell

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 ImagesBee eyeball Edge of mosquito

wing

Hairs on a fly

Images: The Bugscope Project, Beckman Institute, University of Illinois at Urbana-Champaign. http://bugscope.beckman.uiuc.edu/

Atomic Force microscopy (AFM)

A fine ceramic or semiconductor tip moves over a surface much the same way as a photograph needle scans a record.

Image: © The Exploratorium, www.exploratorium.edu

AFM Images

Virus crystal DVD recording marks

SynchrotronA 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 proteinsThere is an Australian synchrotron in Melbourne.

Other Ways of MeasuringWe 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

Did you know…

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• What is light?• What is the speed of light?• What is the natural source of light?• What is laser light?• What is a luminous object?• What is a non-luminous object?• What is the electromagnetic spectrum?• What is the wavelength of visible light?• What is diffraction?

Revision Questions1. What is a nanometer?2. List 3 objects that are in the

nanometre range.3. What is the average diameter of a

human hair?4. Why do scientists want to measure

and visualise the nanoscale?5. What is the link between the

synchrotron and nanotechnology?