Ray diagrams

• What type of lenses cause light rays to diverge?

  Concave lenses
• What symbol represents a concave lens in ray diagrams?

  A V shape with outward points
• What is the axis in a ray diagram?

  A horizontal line through the lens
• What are the focal points in a ray diagram?

  Points on either side of the lens
• What is another name for the focal point?

  Principal focus
• What does the label 2f represent in a ray diagram?

  Twice the distance of the focal point
• How do you represent an object in a ray diagram?

  As a point near the top of the object
• What happens to the ray that passes through the center of a concave lens?

  It continues straight without refraction
• How is the angle of refraction determined for the first ray in a concave lens?

  By drawing a virtual ray to the focal point
• What type of image is formed by a concave lens?

  Virtual image
• Why is the image from a concave lens always virtual?

  Because one ray used is virtual
• What type of lenses focus light onto a single point?

  Convex lenses
• How do the V shapes at the ends of a convex lens differ from a concave lens?

  They point inward, getting narrower
• What happens to the ray passing through the middle of a convex lens?

  It continues straight without refraction
• How do you find the image location in a convex lens ray diagram?

  By finding where the rays cross
• What characteristics describe the image formed by a convex lens?

  Real, inverted, and smaller than the object
• What happens if the object is exactly two times the focal distance from a convex lens?

  The image is real and the same size
• What occurs if the object is between the focal point and the lens?

  The refracted rays won't meet
• How do you find the image when the object is between the focal point and the lens?

  Trace the rays backwards to find the image
• What characteristics describe the image formed when the object is between the focal point and the lens?

  Virtual, upright, and larger than the object
• What are the steps to draw a ray diagram for a concave lens?

  1. Draw the concave lens symbol.
  2. Add the axis and focal points.
  3. Draw incident rays from the object.
  4. Identify the point where rays cross.
  5. Comment on the image characteristics.
• What are the steps to draw a ray diagram for a convex lens?

  1. Draw the convex lens symbol.
  2. Add the axis and focal points.
  3. Draw incident rays from the object.
  4. Identify the point where rays cross.
  5. Comment on the image characteristics.
• What are the differences between images formed by concave and convex lenses?

  Concave lens:

  • Always virtual
  • Upright
  • Smaller than the object

  
  

  Convex lens:

  • Can be real or virtual
  • Inverted or upright
  • Size varies based on object distance