Railway Science (Physics-Light and Optics) (Part-V)

Behind the retina. Hypermetropia (Long-Sightedness) - Lens used - Convex. Other eye diseases : Myopia (Near-Sightedness) - Image Location - Front of Retina. Lens Used - Concave Lens. Presbyopia - The gradual loss of your eyes' ability to focus on nearby objects. Lens - Bifocal Lens. Image Location - behind the Retina.

real and inverted. The retina is like the camera film of the eye. It's a layer at the back of your eye that's sensitive to light. When light hits it, it sends signals to your brain, which turns them into the images you see.

Black. In space, due to the absence of the atmosphere the light rays do not refract and reach the astronomer's eyes therefore it appears black. On Earth, the sky appears blue due to the presence of the atmosphere. Atmosphere refracts light rays coming from the sun and we see the color of the sky.

Radius of curvature is equal to twice the focal length. The equation R = 2f, represents the relationship between the radius of curvature (R) and the focal length (f) of a spherical mirror. This equation applies to both concave and convex spherical mirrors. For concave mirrors, the focal length is negative, and for convex mirrors, the focal length is positive.

At focus. Image Formation by Concave Mirror: Object at center of curvature - Image also at center of curvature. Object beyond center of curvature: Image between center of curvature and focal point. Object between C and F : position of image will be beyond C.

Positive. Convex mirrors: These are also known as diverging mirrors because they reflect light rays away from each other, creating a wider field of view than flat mirrors. Focal length : This is the distance between the mirror's surface and its focal point, where parallel rays of light seem to converge after reflection.

Both laws of refraction and reflection state that: The incident ray refracted ray, and the normal to the interface of two media at the point of incidence all lie on the same plane.

Air. Optical Density - A property of a transparent material that measures the speed of the light through the material. Highest optical Density - Diamond.

Air. The Refractive Index of a medium is defined as the ratio of the speed of light in a vacuum to the speed of light in the medium. It is also called an absolute refractive index. Absolute refractive index of some material media: Air (1.0003), Ice (1.31), Water (1.33), Alcohol (1.36), Diamond (2.42), Turpentine oil (1.47), Kerosene (1.44), Crown glass (1.52), Rock salt (1.54), Sapphire (1.77), Dense flint glass (1.65), Benzene (1.5).

Both are concave. According to the sign convention, the focal length of concave lens is always negative. The focal length of a convex lens is always positive. The focal length of a concave mirror is negative while that of a convex mirror is positive.