What are these devices have in common?

Magnifying Glass

Microscope

Telescope

LensIs a curved piece of glass or some other transparent material that used to refract light.

A piece of curved and polished glass or other transparent material that forms an image by refracting and focusing light passing through.

Two types of lens

Diverging lens or Concave lens

Converging lens or Convex lens

Converging or Convex lenses

Are those which thicker in the middle than they are at the

edge.

Types of Converging or Convex lenses

Double Convex

Plano convex

Concavo convex

Parts of a Convex Lens

Principal Axis ( P )

Parts of a Convex Lens

Centre of Curvatures

C C’

Parts of a Convex Lens

Principal Focus

F F’

Parts of a Convex Lens

Optical Centre

Parts of a Convex Lens

Focal Length

Image Formation of Convex Lens

F’

The ImageReal and Inverted

Real Focus

Diverging or Concave lenses

Are those which thinner in the

middle than they are at the edge.

Types of Diverging or Concave lenses

Double Concave Plano Concave Concavo -concave

Parts of Concave Lens

Principal Axis ( P )

Parts of Concave Lens

Centre of Curvatures

C C’

Parts of Concave Lens

Principal Focus

F F’

Parts of Concave Lens

Optical Centre

Parts of Concave Lens

Focal Length

Image Formation of Concave Lens

F

The Image

Virtual and Upright

Virtual Focus

Applications of Lenses

Lenses are one of the most important devices used in Optical Instruments.

Answer the following questions:

When rays parallel to the principal axis of a concave lens are refracted, they pass through ___.

a. any point along the axis b. the center of curvature c. the principal focusd. the midpoint of the lens

Which property of light waves makes the images seen through lenses?a.reflection b.refractionc.diffraction d.interference

A lens is used to __. a. refracts light b. reflects light c. diffracts light d. all of the above

A kind of lens which is thicker at the middle and thin at the edges.a.converging lensb.diverging lens c.concave lensd.double concave lens

A kind of lens which is thinner at the middle and thicker at the edges.a.converging lensb.diverging lens c.concave lensd.double concave lens

Bring the following

PencilRuler

Laboratory Manual

F2F 2F’F’