Converging lens

Object radiates light in all directions. The rays passing through a lens are refracted twice. Converging (convex) lens refracts light such that the rays parallel to principal axis sre refracted to the focal point of the lens.

The focal length is the distance between focal point and the axis of symmetry of the lens. Reciprosal of the focal length is the optical power of the lens in dioptres (D). +4.0 D eye glass is converging lens of 0,25 m focal length.

Try image formation of the converging lens. It is possible to have image/virtual image/no image at all. Examine how is it possible. If the image is formed by real rays of light it is real. The virtual image is created by purely imaginary, mathematical, extensions of the rays of light.

Thin lens equation: 1/f = 1/p + 1/q. Can you derive it using the similar triangles below?

The linear magnification m is determined as: m = hi / ho. Use the similar triangles above to show that m = q / p.