Download Walk of Discovery: Light

Walk of Discovery: Light
The year 2015 was the International Year of Light. To celebrate, we created a path of
discovery through our exhibits that focusses on the amazing spectacle of light: what it is,
how it works, and how we use it. Follow the trail on the map, and gather some extra
information from this resource. Happy exploring!
The Extra Stuff
Exhibits with some extra information here are labelled with a * on the map.

The Distorted Reflection mirrors reflect light at different directions, making the
image seem distorted. This is called the Law of Reflection, where the angle of light
hitting the mirror (incident light, i) will equal the angle of light reflecting (reflected
light, r) from the mirror (as in the diagram). This law can be seen in exhibits 1, 9, 10,
13, 14, 15, and 16.
i
r
Law of Reflection:
angle i = angle r
mirror
When the mirror is curved we see the reflection as warped, even though the rays of
light are still following this same rule – the drawing below shows how the reflecting
light on a convex (bulging outwards) mirror is spread out to make us look taller.

Air Message gives us a representation of an optical fibre. You may have heard about
the NBN (National Broadband Network); this network uses optical fibres to get
cybernetic information to and from our homes. The fibres are tiny, and each cable
contains 576 fibres – this allows the transfer of 2074 Petabits of information per
second. That’s equivalent to 32.4 million million phone calls per second!

In Smart Glass all the infrared light (which we can’t see but feel as heat) is reflected
away by the transparent coating, so the infrared light cannot heat the glass.
This allows Discovery to have beautiful sunshine light up the exhibits, without the
roasting heat. Since we don’t have to turn on the air conditioners as much, we
reduce out energy usage! This was part of Discovery’s energy efficiency and
sustainability upgrade. Other upgrade features can be seen in exhibits 4 and 6.

Activity: For a Sundial to work outdoors, which direction (North, South, East or
West) does the 12 o'clock need to point in order for it to work? And what happens
during Daylight Savings time?

Incandescent bulbs use 95% of their energy for heat (infrared light), and only 5% for
light that we can see – making them very inefficient! Light Emitting Diodes (LEDs)
do not emit heat, making them much more efficient. Such a Bright Idea.
Activity: Look at the different bulbs paper ‘rainbow’ glasses, if available. Do you see
any difference in the spectra, or rainbow, from each bulb?

Hot spot shows a technique used in Solar Thermal plants to create electricity. The
sun’s light is concentrated to a spot which heats up a material – the first step in
steam-driven electricity plants.

You might recognise the effects of See who? from TV series and movies, especially
crime shows! With the right lighting, this is a one-way mirror, just like in a
detective’s interview room.

Activity: In Frozen shadows, your shadow is sharp when you stand close to the wall
and blurry when you are further away. Try it out!

Looking through the Telescopes you are seeing an image of light that has travelled
millions and millions and millions of kilometres to Earth. Light can travel very very
far! But we can’t hear these galaxies because sound can’t travel in empty space like
light can, so we will never hear these galaxies…

Black holes are so names because they are 'dark': they don't emit any light!
Astronomy works by detecting, measuring and comparing the entire spectrum of
light: radio waves, microwaves, infrared waves, visible light, ultra violet, x-rays,
gamma rays. But black holes don't emit any of that, so we just can't tell what is going
on: we have no information – we are in the dark!

Activity: Across the Discovery Centre’s floor you can see a large rainbow. If this was
a real rainbow, where would the Sun be so you could see it from where you are
standing?
1. Distorted Reflection*
2. Air message*
3. Smart Glass*
18
6
4. Cool Shade
5. Sundial*
6. Bright Ideas*
7. Hot Spot*
17
6
8. Message Stick
13
9. Reflecting reflections
14
15 16
10. See who?*
1
2
11. Frozen Shadows*
3
12. Mirror Window
4
13. Distorted Image
5
14. Head on a platter
6
12
7
2
16. Mirror Corridor
8
17. Telescopes*
9
18. Black Hole*
10
1
15. See to infinity
11