Lenses and Light Quiz

Lenses and Light

• Lenses use refraction to focus or disperse light
• Convex lenses bulge outwards, causing parallel light rays to converge at the principal focus (also called the focal point)
• Convex lenses are also called converging lenses
• Concave lenses cave inwards, causing parallel light rays to disperse or spread out
• Lenses have a principal focus on both sides, equidistant from the center
• The focal length is the distance between the principal focus and the center of the lens.
• A shorter focal length indicates a more powerful lens, meaning it refracts light more strongly.
• Lens power can be increased by making the lens more curved or using a material that refracts light more strongly.

Real and Virtual Images

• Images form at points where light rays from a point on an object appear to converge
• Real images are formed when light rays actually converge. These images can be captured on a screen.
• Virtual images are formed when light rays do not actually converge. These images cannot be captured on a screen.
• Examples
  • Real image: The image formed on the retina of your eye
  • Virtual image: The image you see in a mirror
  • Real images can be either upright or inverted, larger or smaller than the object.
  • Virtual images are always upright and smaller than the object.