Year 9

The light of my life.

• Lesson 1; What is light?

Brain teaser.

• What is at the beginning of eternity, the end of time and space, the beginning of every end, and the end of every place?

What is light?

• Light is also called radiant energy.

• Light is composed of photons, which are small pieces of energy.

How does light travel?

• Light travels in straight lines, in a wave pattern.

Model; slinky

Electromagnetic spectrum

Handout

The electromagnetic spectrum.

• The EMS is a way of showing all of the different energy waves in the universe.

• They range from very short wavelengths, such as gamma rays (b), to very long wavelengths such as radio waves (a).

Gamma rays

• The shortest wavelength ray, thus it has the highest energy.

• Gamma rays are made when isotopes break down, releasing energy.

• Can be used to kill cancer cells in some people.

X rays

• The next longest wave.

• X rays are also high energy, they can pass through skin and muscle, but are stopped by bone.

• This is why they are used to look at peoples bones!

UV rays.

• Ultra-violet rays are the next longest ray.

• They are made in the Sun and travel to Earth.

• Most are reflected back into space by the ozone layer, but some travel to Earth’s surface.

• They cause sunburn, which is why we should…

Visible light.

• The part of the EMS we can detect.

• It is made of 7 different coloured wavelengths;

• Red, Orange, Yellow, Green, Blue, Indigo & Violet.

• Violet has the shortest ʎ and red the longest ʎ.

IR rays.

• Infra-red rays are longer than visible light, we can’t see IR but some animals can.

• IR is also called ‘heat waves’ and can be detected using a thermal camera (or a speed camera!)

Microwaves.

• Microwaves get water excited! It causes the molecules to vibrate more and more quickly and thus heat up.

• That’s how a microwave oven works; it gets the food to cook itself!

Radio waves.

• Long waves, up to 100km long!

• When received by an antenna, they are converted to sound.

What can we see?

• We can only see a very small part of the EMS, the visible light section (400 - 700λ).

• Some insects can see ultraviolet (UV) light and cats use infrared (IR) to see in the dark.

• Lesson 2; light and dark.

Luminosity.

• Luminous objects give off their own light; the Sun, lamps etc.

• Non luminous objects bounce light off their surfaces, but don’t make their own light; mirrors, the Moon etc.

Shadows.

• A shadow is formed when a solid object blocks light rays.

Shadows3

12 noon

15

2 4

SunriseSunset

Mid morning

Mid afternoon

5 1

4 23

Sundials.

Modern Aztec

• A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style (a thin rod or a sharp, straight edge) onto a flat surface marked with lines indicating the hours of the day.

• As the sun moves across the sky, the shadow-edge lines up with different hour-lines on the plate.

Summary; use the words to fill in the gaps.

Distance lamp medium shadow source straight vacuum

• A desk _______ gives out light. • Something that gives out light is called a _______ of

light.• Light travels in _______ lines.• Light does not need a ______ to travel through. • Light from the Sun travels through the _____ of space

to reach us. • A light year is the ______ light travels in one year.• When an object blocks light there is a

_____________.

• A desk lamp gives out light. • Something that gives out light is called a

source of light.• Light travels in straight lines.• Light does not need a medium to travel

through. • Light from the Sun travels through the

vacuum of space to reach us. • A light year is the distance light travels in

one year.• When an object blocks light there is a

shadow.

• Lesson 3; Reflectors and non reflectors.

Reflector or non reflector?

• Why do some surfaces reflect and others not?

• Collect a sample from the tray.

• Set up the light boxes and see what will reflect and what will not.

• What do the reflectors have in common?

• What about the non-reflectors?

Reflectors are…

• Smooth

• Pale in colour

• Shiny

Non reflectors are…

• Rough

• Dark in colour

• Dull

Transparent, translucent or opaque?

• Transparent: completely see through.

Glad wrap.

• Translucent: somewhat see through.

Wax paper.

• Opaque: not see through.

Tin foil, you

Law of reflection.

Law of reflection.

• The angle of incidence is always equal to the angle of reflection

Key

I= incident ray

R= reflected ray

N= normal line

Øi = angle of incidence

Ør = angle of reflection

• Lesson 4; drawing ray diagrams.

Drawing ray diagrams

1. Draw the outline of ray box and mirror.2. Draw a dot where the light leaves the ray

box, another dot further along the light ray, and join the two using a ruler.

3. Draw a normal where the light ray hits the mirror surface with a ruler.

4. Put a dot where the light ray leaves the mirror and another further along the ray. Connect the dots with a ruled line.

5. Label lines/apparatus and draw arrows showing the direction of the light.

Light Box

Mirror

Activity

• Complete a ray diagram for;

1. Plane mirror (measure angles)

2. Deeply convex mirror

3. Shallow convex mirror

4. Deeply concave mirror

5. Shallow concave mirror

Plane mirror

Deeply convex mirrorShallow convex mirror

Shallow concave mirror Deeply concave mirror

• Lesson 5; fun with mirrors.

Making shapes with light.

Mirror drawing

• Fold a piece of paper in half and rule a line down the middle.

• Draw a simple picture on one side of the line, place the mirror along the line.

Now..

• Draw the other half of the picture, using the mirror.

• Have a go with the mirror maze as well.

Up periscope.

• Lesson 6; Lasers.

Safe

Alarm clock

Laser burglar alarm

• Use the handout to complete the alarm task.

• Lesson 7; Laws of refraction.

Law of refraction

• When light enters an optically denser medium it slows down and bends towards the normal.

Activity

• Complete a ray diagram for;

1. Oblong block

2. Triangle block

3. Convex lens block

4. Half circle block

‘Magic’ tricks

• Pencil and beaker.

• Coins and beaker.

• Prism.

• KW 714

• How do we see?

The eye.

http://www.kscience.co.uk/animations/eye_drag.htm

How do we see?

• Incoming light must pass through the cornea and pupil.

• The lens then focussing the light on to the retina.

• The retina then sends electrical signals to the brain, telling you what can see.

Video.

• Let’s watch the Discovery Channel video on sight!

Make the model eye.

• Make the model eye, glue it into your notes and label the parts.

• Follow the colour code.

• Don’t forget the clear layers.

• Colour the iris in the same colour as your own eye.

• Lesson 9; the pinhole camera.

The pinhole camera.

• Follow the instruction to make a ‘pringles’ pinhole camera.

Neat!

The image is upside down!

• The image transferred to your retina is upside down and must be flipped by your brain.

Today;

• Lesson 10; eye dissection.

Eye dissection

• Follow me as we complete the eye dissection.

• Remember this came from a living animal, so respect the materials provided for you.

Lenses.

• Concave

• Diverging lens

• Convex

• Converging lens

The lens

• The light enters the eye and is focussed on the retina.

• Set your ray box with a convex lens.

• Draw a ray diagram showing the focal point.

Optical illusions.

• Take a look at the optical illusion cards,

• What’s happening?

• Your eye tricks your brain!• http://www.youtube.com/watch?v=SvNjsOl1Ag0

Today;

• Lessons 11 13 project work.

Today;

• Lesson 14; The colour of light.

The colour of light.

• Set up a prism inside the rainbow box and observe the light which leaves the prism.

White light is actually…

• Made up of• Red• Orange• Yellow• Green• Blue• Indigo• VioletROYGBIV

It’s about waves!

• Each colour has a different wave length, when they combine they create white light.

Newton’s colour wheel.

• Make a colour wheel.• 900 Red• 450 Orange• 450 Yellow• 450 Green• 450 Blue• 450 Indigo• 450 Violet

• Primary colour lights.

Primary colour lights.

Yellow

White

Magenta

Cyan

Activity

• Read Pg 65, in Science book Y9.

• Copy the notes about primary colour lights.

• Then answer Q5 on Pg 67.

Reflection of colour.

Blue

Green

Filters.

• Through a red filter; red colours look brighter, light colours look pink and all other colours look dark.

• Through a blue filter; blue colours look brighter, light colours look blue and all other colours look black.

• Through a green filter; green colours look brighter, light colours look green and all other colours look black.

Colour blindness

• Lesson 16; revision.

• Complete the revision sheet, then play the millionaire game.

Today;

• Lesson 17; Final test today.