OBJECT: To determine the focal length of concave mirror
want answer's photoas from shivlaal practical book
Answers
Answer:
Centre of curvature: For a curved mirror, the centre of curvature, C can be defined as the centre of a hollow glass sphere of which a curved mirror is a part.
Radius of curvature: For a curved mirror, the radius of curvature, R can be defined as the radius of the hollow glass sphere of a spherical mirror is part.
Principal axis: Principal axis is defined as the imaginary line passing through the pole and centre of curvature of the spherical mirror.
Principal focus: Principal focus is defined as a point at which the reflected rays meet or appear to meet for the spherical mirror. For a concave mirror, the principal focus is in the front and for a convex mirror, the principal focus is at the behind.
Below is an experiment to determine the focal length of a concave mirror and convex lens.
Aim
To determine the focal length of:
Concave mirror
Convex lens by obtaining the image of a distant object.
Theory
How to find focal length of concave mirror?
Following are the ways to obtain the focal length of the concave mirror:
A concave mirror is defined as the spherical mirror whose reflecting surface is curved inwards and follows laws of reflection of light.
The light rays coming from a distant object can be considered to be parallel to each other.
If the image formed is real, inverted and very small in size, then the parallel rays of light meet the point in the front of the mirror.
The image formed by the convex lens is real and can be obtained on the screen.
f is used to denote the difference between the principal axis P and the focus F of the concave mirror.
How to find the focal length of convex lens?
Following are the ways to obtain the focal length of convex lens:
The convex lens is thicker in the middle and thinner at the edges and is also known as the converging lens.
The refracted rays from the parallel beam of light converge on the other side of the convex lens.
If the image is obtained at the focus of the lens, the image would be real, inverted and very small.
f is the focal length which is the difference between the optical centre of the lens and the principal focus.
The image can be obtained on the screen as the image formed by the lens is real.
To determine focal length of a given concave mirror
Materials Required
A concave mirror
A measuring scale
A screen holder
A mirror holder
A mirror stand