Energy and Change Light Electricity Energy
Introduction
Questions to
think about
How we see
Reflection
Refraction
What is refraction?
Exploring prisms
Lenses & images
Refraction
Gems
Summary
Colour
Conclusion
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Introductory activity: What is refraction? Overall management

Many of the optical devices you examined at the start of this module, such as the telescope, microscope and magnifying glass, use lenses.
How do lenses work?

Refraction
Refraction is a scientific term. It has many everyday effects. It is the cause of heat haze, and of the dappled light at the bottom of a shallow pool. It helps makes diamonds sparkle and plays a part in rainbows.

What to use
The equipment is set out at stations around the room.
What to do Strategies
Your group should move from station to station as they become available and examine the equipment there. Then answer the Investigation questions for each station. At the end of the lesson, these questions will be discussed by the whole class.
Depth of two coins (Station 1)

  1. Examine the two coins by looking vertically downwards from above the beaker.
    One coin is in a beaker of water and another is alongside the beaker.
    A coin in a beaker of water
Investigation question:
  1. What did you observe about the appearance of the coin in the beaker compared with the coin alongside the beaker?
Bent and broken pencil (Station 2)
  1. Dip the pencil in the large beaker of water at about 45° to the vertical.
  2. Examine the appearance of the pencil when viewed from the side of the beaker, and from looking down at an angle to the surface of the water.
    A pencil viewed through a beaker of water
Investigation question:
  1. What did you observe about the appearance and shape of the pencil?
Wavy window glass (Station 3) Hints
  1. Stand near a window and look through a pane of glass at a small angle to the surface of the glass.
    Looking out a window at an angle
  2. Look at the distant scene through the glass and gently move your head about. Some glass is not perfectly flat and this will affect what you see.
Investigation question:
  1. Describe any wavy effects you saw when you looked through the glass pane.
Watch glass magnifying glass (Station 4)
  1. Partly fill a deep watch glass with some water.
  2. Carefully hold the watch glass over some writing and observe the effect.
    Looking through a watch glass at writing Hints
Investigation question:
  1. Describe the effect you observed when you looked through the watch glass of water.
Face through a beaker (Station 5)
  1. Look at a member of your group whose face is close behind a large beaker of water.
  2. Observe the shape of his or her face.
    Looking through a beaker of water
Investigation questions:
  1. Describe the appearance of the face of the person behind the beaker.
  2. Would this effect occur if the beaker was empty?
  3. What would happen if the beaker contained milk?
Water drop microscope (Station 6)

Hints One of the first microscopes invented used a small drop of water as the magnifying glass. The drop is held in a smooth round hole in a sheet of metal or stiff plastic.



  1. Place a drop of water on the apparatus provided.
  2. Examine a small object such as the text on this page through the drop.
 A water droplet used to view objects
Investigation question:
  1. How does changing the size of the drop affect the magnification of the image?
Heat waves (Station 7)
  1. Turn the slide projector on.
  2. Focus the light onto the white screen 3 m from the projector.
  3. Light the Bunsen burner and place it in the light of the projector 40 cm in front of the screen.
  4. Observe the patterns on the screen.
    Heat wave patterns
Investigation questions:
  1. Make a sketch of what you observed.
  2. Where might you have seen this effect before? Do different flames (air hole of the Bunsen burner open or closed) make different effects on the screen?
Examining eye glasses (Station 8)
Hints Examine the range of eye glasses at this station.

  1. Hold them about 30 cm from your eyes and examine writing on a page in a book or newspaper.
  2. Hold up the eye glasses at arm's length and look at the scene outside the window.
Investigation questions:
  1. Which pair of glasses enlarged the image of the text on this page?
  2. Which pair made the text look smaller?
  3. Which made the scene outside the window look smaller?
  4. Which made the scene outside the window look upside down?
  5. Did any of the glasses make the images look stretched and distorted?
  6. Do the pairs of glasses that had the same effects have anything in common?

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