Lenses

Cards (71)

  • Lenses are precisely shaped pieces of glass that have been developed and used in corrective glasses, telescopes, microscopes, binoculars, and magnifying glasses.
  • Convex lenses are objects or shapes that curve or bulge outwards, like a circle or sphere.
  • Concave lenses are objects or shapes that curve inwards, rather than bulging outwards.
  • The principal focus of a lens is where light rays appear to converge or to diverge from.
  • In a ray diagram, a convex lens is drawn as a vertical line with outward facing arrows to indicate the shape of the lens.
  • The focal length of a lens is the distance between the centre of the lens and the focal point.
  • Concave lenses are thinner in the middle than they are at the edges, causing parallel rays to diverge.
  • In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.
  • The distance from the lens to the principal focus is called the focal length.
  • from the lens, the image formed by a convex lens is upright and magnified.
  • Lenses are precisely shaped pieces of glass that have been developed and used in corrective glasses, telescopes, microscopes, binoculars, and magnifying glasses.
  • The images formed by a lens can be upright or inverted, magnified or diminished, real or virtual.
  • Magnification is the process of making an image larger or smaller than the object.
  • Convex and concave lenses are used in magnification.
  • Rays from a light source further from the principal axis will result in a smaller image than the object.
  • Rays from a light source will appear to come from the same side of the principal axis, meaning the image will be upright.
  • A real image is an image that can be projected onto a screen.
  • A virtual image appears to come from behind the lens.
  • A ray diagram is a diagram that represents the direction and angle of travel of light.
  • To draw a ray diagram, draw a ray from the object to the lens that is parallel to the principal axis.
  • Once through the lens, the ray should pass through the principal focus.
  • A ray which passes from the object through the centre of the lens is also represented in some ray diagrams.
  • Some ray diagrams may also show a third ray.
  • Convex lenses are objects or shapes that curve or bulge outwards, like a circle or sphere.
  • The type of image formed by a convex lens depends on the lens used and the distance from the object to the lens.
  • Magnification is the ratio of the image height to the object height when using lenses.
  • Cameras and eyes contain convex lenses.
  • Peep holes are set into doors so the occupant can identify a visitor before opening the door.
  • Lenses and curved mirrors can produce magnified images.
  • Ray diagram for an object placed less than one focal length from a convex lens.
  • Film must be loaded into the projector upside down so the projected image is the right way up.
  • This works when the object is placed at a distance less than the focal length.
  • Only the person using the magnifying glass can see the image.
  • A magnifying glass is a convex lens used to make an object appear much larger than it actually is.
  • Concave lenses always produce images that are upright diminished virtual.
  • When a light ray splits up or spreads out on the other side of the lens, it is deflected from a straight path.
  • In a film or data projector, this image is formed on a screen.
  • For an object viewed through a concave lens, light rays from the top of the object will be refracted close refracted.
  • Projectors contain convex lenses.
  • For a distant object that is placed more than twice the focal length from the lens, the image formed by a convex lens is upright and magnified.