Light and Mirrors

A reflecting telescope uses concave mirrors as they produce images similar to the images produced by convex lenses i.e. upright and smaller than the object.

The magic lantern used a concave mirror in back of a light source to direct as much of the light as possible through a small rectangular sheet of glass.

Concave mirrors project a beam of light outward, which is required in a cinema projector.

Concave mirror forms an image of the sun at a distance of 12 cm.
So the focal length of mirror is 12 cm.
Radius of mirror is $f \times 2=24cm$
For shaving we need to get a virtual image which should be magnified and erect.
So the mirror must be kept at a reasonable distance of 8-10 cm which is within focus and pole.
As the radius is 24cm the object placed at center forms image at the same place
Options $B,C$ are correct.

Concave mirrors are used in telescope to reflect light.

The concave mirror is used by the dentist as the image formed by the concave mirror when placed between pole and focus is magnified and erect and it provides a clear image to repair tooth cavities.

A ray of light which bounces off the surface of mirror is called reflected ray.

Normal is perpendicular drawn to the surface at the point of incidence so that angle between incident ray and normal is angle of incidence.

Normal is the line drawn perpendicular to the surface of the mirror at the point of incidence. 

According to definition, when a beam of light appears to meet at a point, after reflection, from a mirror then the image formed is known as virtual image. It cannot be obtained on a screen.

According to definition, the perpendicular drawn to the surface of the mirror at the point of incidence is known as normal ray.

When a mirror forms an image, the left and right sides of the image are interchanged. This phenomenon is called lateral inversion as the image is laterally inverted.

If the image always appears erect, then the mirror is either plane or convex. So, on the basis of the given options, the mirror is likely to be a plane mirror.

According to definition, 
i) A ray from the object, travelling towards the mirror is the incident ray.
ii) Angle between reflected ray and normal is the angle of reflection.
iii) The angle between reflecting surface and the reflected ray is known as the glancing angle of reflection.

According to definition of reflected ray and point of incidence, the ray which bounces off the surface of the mirror when the incident ray strikes the mirror is known as the reflected ray. The point at which incident ray meets the mirror is called the point of incidence.

The back of a mirror is usually covered with some sort of darkly colored, protective material to stop the silver coating from getting scratched, and also to reduce the risk of any light seeping through from behind. Silver reflects light better than almost anything else and that's because it gives off almost as many light as fall on it in the first place.

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