Unit Summary

Questions

Summary

1. What objects emit their own light? What objects need a light source to be seen?

1.1 What objects emit their own light? What objects need a light source to be seen?

1.2 How is looking at the sun or bright light dangerous?

• Sources of light can be natural or artificial (man-made).
  
  
• Looking directly at the Sun and certain kinds of light sources can be dangerous.  Eye protection is necessary.

2. How does light interact with other materials?

2.1 How can we use light to classify objects as transparent, translucent, or opaque?

2.2 How do objects create shadows?

• Light passes through transparent objects.
  
  
• Light is blocked by opaque objects.
  
  
• Some light passes through translucent objects.
  
  
• Opaque and translucent objects create shadows.
  
  
• Shadows become larger as the object gets closer to its light source.
  
  
• Shadows are shortest at midday when the Sun is higher in the sky.

3. How does light travel?

3.1 What happens when light hits a surface? (absorbed, reflected, or refracted)

3.2. How can light be broken into colours or combined to make a new colour?

3.3 How do various optical devices work?

• Light is absorbed by dark, rough opaque surfaces.
  
  
• Light is reflected by shiny, smooth opaque surfaces.
  
  
• Light is refracted through various materials (or objects such as prisms and lenses).
  
  
• White light can be separated into a spectrum.
  
  
• Various colours of light can be combined to produce new colours.
  
  
• Because light can be reflected and refracted, it can be used in many optical devices.