Aim	To determine the focal length of a concave mirror.
Apparatus Required	A concave mirror A stand for the mirror A distant object (such as a building or a tree) A screen A measuring tape or ruler A light source (optional)
Theory	To find the focal length of a concave mirror, one can use the following steps: A concave mirror has a curved reflecting surface that is inwardly curved and follows the laws of light reflection. When light rays from a distant object fall on the concave mirror, they can be considered to be parallel to each other. If the image formed by the mirror is real, inverted, and very small, the parallel rays of light converge to a point in front of the mirror. The focal length, denoted by f, represents the distance between the principal axis P and the focus F of the concave mirror. How to determine the focal length of a convex lens: To find the focal length of a convex lens, one can use the following steps: A convex lens is thicker in the middle and thinner at the edges, and it is also known as a converging lens. When a parallel beam of light passes through the convex lens, the refracted rays converge on the opposite side of the lens. If the image is obtained at the focus of the lens, it will be real, inverted, and very small. The focal length, denoted by f, represents the distance between the optical center of the lens and the principal focus. The image formed by the lens is real and can be projected onto a screen.
Procedure	Set up the concave mirror on the stand in a well-lit room. Place the distant object in front of the mirror, beyond the center of curvature. Adjust the position of the mirror until a clear, sharp image of the object appears on the screen placed behind the mirror. Measure the distance between the object and the mirror (u) using a measuring tape or ruler. Measure the distance between the screen and the mirror (v) using a measuring tape or ruler. Repeat steps 3 to 5 for different positions of the object and the screen. Calculate the focal length (f) of the concave mirror using the mirror formula 1/f = 1/u + 1/v.
Observation and Result	Observations: A real, inverted image of the distant object is formed on the screen. The distance between the object and the mirror (u) and the distance between the screen and the mirror (v) are measured. Results: The focal length (f) of the concave mirror is calculated using the mirror formula. Experiment to determine the focal length of a convex lens:

Aim	To determine the focal length of a convex lens by obtaining the image of a distant object.
Apparatus	A convex lens A stand for the lens A distant object (such as a building or a tree) A screen A measuring tape or ruler A light source (optional)
Procedure	Set up the convex lens on the stand in a well-lit room. Place the distant object in front of the lens. Adjust the position of the lens until a clear, sharp image of the object appears on the screen placed behind the lens. Measure the distance between the object and the lens (u) using a measuring tape or ruler. Measure the distance between the screen and the lens (v) using a measuring tape or ruler. Repeat steps 3 to 5 for different positions of the object and the screen. Calculate the focal length (f) of the convex lens using the lens formula 1/f = 1/u + 1/v.
Observation and Result	Observations: A real, inverted image of the distant object is formed on the screen. The distance between the object and the lens (u) and the distance between the screen and the lens (v) are measured. Results: The focal length (f) of the convex lens is calculated using the lens formula.