IV. Answer briefly.
1. Define focal length.
2. Give any two applications of a concave
and convex mirror.
3. State the laws of reflection
4. Define the refractive index of a medium.
5. State Snell's law of refraction
newer in detail.
Answers
1. Focal length: The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. It is the point where parallel rays of light meet or converge. The focal length varies with the sign (positive or negative) depending upon the nature of the lens and mirror(concave or convex).
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2. Laws of Reflection: The laws of reflection determine the reflection of incident light rays on reflecting surfaces, like mirrors, smooth metal surfaces, and clear water.
Following are the laws of reflection:
The incident ray, the reflected ray and the normal to the surface of the mirror all lie in the same plane.
The angle of incidence is equal to the angle of reflection.
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3. two applications of concave and convex mirror:
1. (Concave mirrors): 1. Concave mirrors are used while applying make – up or shaving, as they provide a magnified image. 2. They are used in torches, search lights and head lights as they direct the light to a long distance.
2. (Convex mirror): 1. Convex mirrors are used in vehicles as rear view mirrors because they give an upright image and provide a wider field of view as they are curved outwards. 2. They are found in the hallways of various buildings including hospitals, hotels, schools and stores. They are usually mounted on a wall or ceiling where hallways make sharp turns.
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