Law Of Reflection

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LAW OF REFLECTION
When a light ray strikes a plane mirror it changes its direction which is known as “reflection”. The light ray, which strikes the mirror, is known as “incident ray” and the ray after reflection is known as “reflected ray”. The perpendicular line which bisects the incident ray and reflected ray is called normal drawn to the point of intersection. The incident ray, reflected and the normal drawn to the point of intersection lie on the same plane. (Fig 1)

When the light reflects in plane mirror the angle of incidence is always equal to the angle of reflection.

Example

When a light ray is directed to a plane mirror from 30’ to the normal, it strikes a point in the other side of it, after reflecting. The angle between the place where light is directed and normal will always be equal to the angle between normal and the point where the light strikes after reflecting.

• Angle of incidence = 30’
• Therefore, angle of reflection = 30’

How do we see the objects in a plane mirror?
We need light to see any object. To see an image of an object in a mirror, you should see in the line of the object. As you sight at the object, light from the object travels to your eye after reflecting in the mirror. The diagram shows that the light reflects off the mirror in such a manner that the angle of incidence is equal to the angle of reflection.

Characteristics of the images formed in a plane mirror
• Virtual
• Laterally inverted
• Equal in size
• Formed at equal distance between the object and the mirror.

REFLECTION IN CURVED MIRRORS
All the light rays follow the reflective laws. We find the image of an object using those reflection laws. The image is the place where two or more rays gets converged at a si...

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...ght can enter the camera. Most cameras have functions that allow a person to view the scene to be recorded, allow for a desired part of the scene to be in focus, and to control the exposure so that it is not too bright or too dim. A data display, often a liquid crystal display, permits the user to view settings such as film speed, exposure, and shutter speed.

HOW DO WE GET THE IMAGE IN A CAMERA?

The above diagram shows the functional ray diagram of a camera. The light enters the camera passing two convex or converging lenses. The lenses of the camera is adjusted in a way that the light from the object passes through the pole of the first lens. And the pole of the first lens is the centre of curvature of the second lens. There the light travels in a straight path.

Characteristics of the image formed in a camera
• Real image
• Inverted
• Diminished

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