Light Reflection and Refraction Test - 17

If the upper half of the concave mirror is covered, the amount of light that gets reflected from the mirror will be reduced. Consequently, the brightness of the image that is formed on the screen will be reduced.

A lens has two spherical surfaces. An imaginary straight line passing through the two centres of curvature of a lens is called its principal axis. The principal axis of the lens should be parallel to the length of the optical bench while performing an experiment, so that errors in experimental values are avoided.

An image formed by a plane mirror is always erect, virtual and of the same size as that of the object. A convex mirror always forms an erect, virtual and a diminished image, for any position of the object.

The spherical mirror and the spherical lens - both are concave. The distance of the principal focus measured from the pole is called the focal length. According to the New Cartesian Sign Convention, the focal length of a concave mirror as well as that of a concave lens is considered negative.

A real image is an image which is located in the plane of convergence for the light rays that originate from a given object. If a screen is placed in the plane of a real image the image will generally become visible on the screen. Examples of real images include the image seen on a cinema screen (the source being the projector), the image produced on a detector in the rear of a camera, and the image produced on an eyeball retina

The net power of the resultant lens is given by the algebraic powers of the individual powers.

Equivalent power of the lens combination, P = P₁ + P₂ = (+4 D) + (-3 D) = +1 D

At the point of emergence, the angle of emergence is measured with respect to the normal at the point of emergence.