The focal length of a convex lens is a measure of the lens's ability to focus light. It is the distance from the center of the lens to the point where parallel rays of light converge after passing through the lens. In a convex lens experiment, the focal length can be determined by measuring the distance from the lens to the point of convergence for a beam of parallel light rays.

One way to conduct a convex lens experiment to determine the focal length is to set up a simple optical bench. This consists of a light source, a lens holder, and a screen. The light source is placed at one end of the bench, and the lens holder is placed a certain distance away from it. The screen is placed at the other end of the bench, and the lens is placed in the lens holder.

To begin the experiment, the lens is positioned so that the light source is at its focal point. This is the point where the light rays coming from the source are brought to a focus by the lens. The distance from the lens to this point is the focal length.

Once the focal point has been located, the screen is moved along the bench until it is in focus. The distance from the lens to the screen is then measured, and this distance is the focal length of the lens.

Another way to determine the focal length of a convex lens is to use a lens formula. This formula relates the focal length of the lens to the indices of refraction of the lens and the surrounding medium, as well as the radii of curvature of the lens. By measuring these quantities, the focal length of the lens can be calculated.

There are several factors that can affect the accuracy of a convex lens experiment, including the quality of the lens, the alignment of the equipment, and any imperfections in the light source. It is important to carefully control these variables in order to obtain accurate results.

In conclusion, the focal length of a convex lens can be determined through a variety of methods, including optical bench experiments and lens formulas. Careful measurement and control of variables is essential for obtaining accurate results in a convex lens experiment.

## In an experiment a convex lens of focal length 15 cm is placed coaxially on an optical bench in front of a convex mirror at a distance of 5 cm from it. It is found that an object and its image coincide, if the object is placed at a distance of 20 cm from the lens. The focal length of the convex mirror is:

Which lens is called a diverging lens? The wire mesh is illuminated to get a bright image. Take out the mirror and place another needle, C, on the same side of the mirror. HYPOTHESIS: The relationship between u and v and the focal length f for a convex lens is given by. It is found that an object and its image coincide, if the object is placed at a distance of 2 0 c m from the lens. THEORY: The focal length of lens, f is related to the object distance, p and image distance, q according to the lens equation.