5.3 Using Lenses to Form Images

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5.3 Using Lenses to Form Images

• A lens is a piece of transparent material that
  can bend, or refract, light rays in useful ways
  to help form a well-focused image.
• A lens can be concave or convex.

See page 190
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Concave Lenses

• Concave lenses are thinner in the middle than at
  the edge.
• Concave lenses cause light rays to diverge.
• Concave lenses produce images that are upright
  and smaller than the object.
• Concave lenses are sometimes used in eyeglasses
  and telescopes.

See page 191
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Concave Lenses
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Convex Lenses

• Convex lenses are thicker in the middle than at
  the edge.
• Convex lenses cause light rays to converge.
• When parallel rays strike a convex lens they come
  together at the focal point.
• A magnifying glass is a good example of a convex
  lens.

See page 192
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Focal length in Convex Lenses
The distance from the centre of the lens to the
focal point is called the focal length. The type
of image a convex lens forms depends on where the
object is relative to the focal point.
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Focal Length in Convex Lenses
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Focal Length in Convex Lenses
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Focal Length in Convex Lenses
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Focal Length in Convex Lenses
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