Concave Lenses (T)

• What should you be able to do by the end of the video regarding concave lenses?

  Draw a diagram to show how an image is formed by a concave lens and describe the properties of the image.
• What are the properties of an image produced by a concave lens?

  • Diminished (smaller than the object)
  • Right way up
  • Virtual (rays do not actually cross)
• What is the difference in thickness between the center and edges of a concave lens?

  The edges are thicker than the center.
• How do concave lenses affect light rays?

  Concave lenses make light rays spread out, causing them to diverge.
• What is the term used for the point where light rays appear to come from in a concave lens?

  Principal focus.
• Why is the image produced by a concave lens described as virtual?

  Because the rays do not actually cross; they only appear to cross at the principal focus.
• What steps are involved in drawing a ray diagram for a concave lens?

  1. Draw a ray from the top of the object through the center of the lens without changing direction.
  2. Draw another ray from the top of the object that passes through the lens and is refracted.
  3. Draw a dotted line from the principal focus to indicate where the rays appear to come from.
  4. Mark the position where the lines meet to show the position of the image.
• How does a concave lens differ from a convex lens in terms of light ray behavior?

  Concave lenses cause light rays to diverge, while convex lenses focus parallel rays to a point.
• What happens if a screen is placed where the image appears in a concave lens?

  No image will be seen on the screen.