Year 9

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Year 9

• The light of my life.

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• Lesson 1 What is light?

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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?

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What is light?

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

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How does light travel?

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

Model slinky
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Electromagnetic spectrum
Handout
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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).

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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.

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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!

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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 Earths surface.
• They cause sunburn, which is why we should

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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 ? and red the longest ?.

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IR rays.

• Infra-red rays are longer than visible light, we
  cant see IR but some animals can.
• IR is also called heat waves and can be
  detected using a thermal camera (or a speed
  camera!)

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Microwaves.

• Microwaves get water excited! It causes the
  molecules to vibrate more and more quickly and
  thus heat up.
• Thats how a microwave oven works it gets the
  food to cook itself!

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Radio waves.

• Long waves, up to 100km long!
• When received by an antenna, they are converted
  to sound.

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What can we see?

• We can only see a very small part of the EMS, the
  visible light section (400 - 700?).
• Some insects can see ultraviolet (UV) light and
  cats use infrared (IR) to see in the dark.

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• Lesson 2 light and dark.

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Luminosity.

• Luminous objects give off their own light the
  Sun, lamps etc.
• Non luminous objects bounce light off their
  surfaces, but dont make their own light
  mirrors, the Moon etc.

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Shadows.

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

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Shadows
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12 noon
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Mid afternoon
Mid morning
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Sunrise
Sunset
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2
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Sundials.
Modern
Aztec
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• 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.

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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
  _____________.

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• 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.

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• Lesson 3 Reflectors and non reflectors.

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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?

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Reflectors are

• Smooth
• Pale in colour
• Shiny

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Non reflectors are

• Rough
• Dark in colour
• Dull

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Transparent, translucent or opaque?

• Transparent completely see through.
• Glad wrap.
• Translucent somewhat see through.
• Wax paper.
• Opaque not see through.
• Tin foil, you ?

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Law of reflection.
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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
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• Lesson 4 drawing ray diagrams.

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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.

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

Light Box
Mirror
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Activity

• Complete a ray diagram for
• Plane mirror (measure angles)
• Deeply convex mirror
• Shallow convex mirror
• Deeply concave mirror
• Shallow concave mirror

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Plane mirror
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• Deeply convex mirror

Shallow convex mirror
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Shallow concave mirror
Deeply concave mirror
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• Lesson 5 fun with mirrors.

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Making shapes with light.
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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.

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Now..

• Draw the other half of the picture, using the
  mirror.
• Have a go with the mirror maze as well.

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Up periscope.
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• Lesson 6 Lasers.

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Lasers
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Alarm clock
Safe
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Laser burglar alarm

• Use the handout to complete the alarm task.

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• Lesson 7 Laws of refraction.

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Law of refraction

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

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Activity

• Complete a ray diagram for
• Oblong block
• Triangle block
• Convex lens block
• Half circle block

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Magic tricks

• Pencil and beaker.
• Coins and beaker.
• Prism.

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• KW 7?14
• How do we see?

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The eye.
http//www.kscience.co.uk/animations/eye_drag.htm
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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.

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Video.

• Lets watch the Discovery Channel video on sight!

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Make the model eye.

• Make the model eye, glue it into your notes and
  label the parts.
• Follow the colour code.
• Dont forget the clear layers.
• Colour the iris in the same colour as your own
  eye.

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• Lesson 9 the pinhole camera.

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The pinhole camera.

• Follow the instruction to make a pringles
  pinhole camera.

Neat!
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The image is upside down!

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

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Today

• Lesson 10 eye dissection.

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Eye dissection

• Follow me as we complete the eye dissection.
• Remember this came from a living animal, so
  respect the materials provided for you.

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Lenses.

• Concave
• Diverging lens

• Convex
• Converging lens

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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.

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Optical illusions.

• Take a look at the optical illusion cards,
• Whats happening?
• Your eye tricks your brain!
• http//www.youtube.com/watch?vSvNjsOl1Ag0

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Today

• Lessons 11 ?13 project work.

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Today

• Lesson 14 The colour of light.

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The colour of light.

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

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White light is actually

• Made up of
• Red
• Orange
• Yellow
• Green
• Blue
• Indigo
• Violet
• ROYGBIV

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Its about waves!

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

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Newtons colour wheel.

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

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• Primary colour lights.

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Primary colour lights.
Magenta
Yellow
White
Cyan
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Activity

• Read Pg 65, in Science book Y9.
• Copy the notes about primary colour lights.
• Then answer Q5 on Pg 67.

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Reflection of colour.
Blue
Green
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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.

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Colour blindness
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• Lesson 16 revision.
• Complete the revision sheet, then play the
  millionaire game.

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Today

• Lesson 17 Final test today.