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Year 8 Science — Light, shadows and reflection

Tell luminous objects from non-luminous, use the straight-line rule to explain shadows, and give the four properties of an image in a plane mirror.

Name: ________________________

Before you start

A torch, an opaque object and a screen — the three parts of a shadow set-up.

1234
  1. 1. Torch
  2. 2. Object
  3. 3. Screen
  4. 4. Shadow

Take away any one of the three and there is nothing to see: no light, no object to block it, or no surface for the dark patch to land on. In everyday life a wall, a floor or the ground plays the part of the screen.

  1. 1.A red ball and a blue ball of the same shape are held in the same place in front of a torch. What can you say about their shadows?

    • a) The red ball casts the darker shadow, because red is the deeper colour
    • b) One shadow is reddish and the other bluish
    • c) Both shadows are the same, because changing an object's colour does not change its shadow's colour
    • d) The blue ball casts no shadow, because blue lets light through

  2. 2.A candle flame shines through a pinhole in a card onto a screen behind it. What does the image look like?

    • a) Too faint to have a shape
    • b) Upside down
    • c) Left and right swapped, but the right way up
    • d) The right way up

  3. 3.Why does a kaleidoscope show so many different patterns?

    • a) Its three mirrors reflect each other's reflections, and turning it rearranges the pieces
    • b) The tracing paper at the end scatters the light into new colours
    • c) The coloured pieces inside change colour as the tube warms
    • d) Its single mirror flips the pattern each time it is turned

  4. 4.What three things do you need in order to see a shadow?

    • a) A source of light, an opaque object, and a screen
    • b) A source of light, a transparent object, and a mirror
    • c) A mirror, an opaque object, and a screen
    • d) Sunlight, a coloured object, and a dark room

  5. 5.A shiny plate held in sunlight throws a bright patch onto a shaded wall, because it has changed the direction the light was travelling in. What is that change of direction called?

  6. 6.Match each item to what it does.

    • A pinhole camera
    • An opaque object
    • A transparent object
    • A shadow
    • blocks light completely
    • lets light pass almost completely through
    • forms an inverted image
    • the dark region formed behind an object

  7. 7.A pen stands in front of a plane mirror, drawn here as the tall bar in the middle. The image is the one drawn with a broken outline. Tap the image of the pen.

    Write the number of the part.

    123

  8. 8.Why is the word AMBULANCE painted reversed across the front of an ambulance?

    • a) So that it can be read from a great distance
    • b) So that it stays readable when the ambulance is moving fast
    • c) So that it reads the right way round in the rear-view mirror of the vehicle ahead
    • d) So that it looks different from ordinary vehicle lettering

Answer key — Year 8 Science — Light, shadows and reflection

  1. 1. c) Both shadows are the same, because changing an object's colour does not change its shadow's colour
  2. 2. b) Upside down
  3. 3. a) Its three mirrors reflect each other's reflections, and turning it rearranges the pieces
  4. 4. a) A source of light, an opaque object, and a screen
  5. 5.
    • reflection
    • reflection of light
  6. 6. A pinhole camera → forms an inverted image; An opaque object → blocks light completely; A transparent object → lets light pass almost completely through; A shadow → the dark region formed behind an object
  7. 7. 3 — The image
  8. 8. c) So that it reads the right way round in the rear-view mirror of the vehicle ahead