SPHERICAL MIRROR

SPHERICAL MIRROR

When the mirror is a part of a sphere, it is called spherical mirror.

ACTIVITY

Take a stainless steel spoon. Bring the outer side of the spoon near your face and look into it.

·     Do you see your image in it?

·     Is this image different from what you see in a plane mirror?

·     Is this image erect?

·     Is the size of the image the same, smaller or larger?

Now look at your image using the inner side of the spoon. This time you may find that your image is erect and larger in size. If you increase the distance of the spoon from your face, you may see your image inverted. You can also compare the image of your pen or pencil instead of your face.

SPHERICAL MIRRORS ARE OF TWO TYPES.

 In concave mirror, the reflective surface is inside the sphere, i.e. is depressed.

In convex mirror, the reflective surface is outside the sphere, i.e. is bulged or protruded.

IMAGE FORMATION IN CONCAVE MIRROR:

In case of concave mirror, the image is usually inverted, real and smaller than the object. When the object is kept too close to the concave mirror, the image is erect, virtual and larger than the object.

Take a concave mirror. Hold it facing the sun. Try to get the light reflected by the mirror on a sheet of paper. Adjust the distance of the paper until you get a sharp bright spot on it. Hold the mirror and the sheet of paper steady for a few minutes. The paper start burning.

Uses of Concave Mirror:

• Concave mirror is used by dentists and ENT specialists to focus a beam of light to see inside a patient’s mouth or ears. 
• Concave mirror is used in solar furnace,
  because rays of sunlight converge at a point once they reflect from the concave mirror. 
• Concave mirror is used as barber’s mirror, because it shows a larger image when object is too close.

IMAGE FORMATION IN CONVEX MIRROR:

In case of convex mirror, the image is erect, virtual and smaller than the object.

Uses of Convex Mirror:

• Convex mirror is used in rear view mirrors, as it shows smaller images from a bigger field of view. 
• Convex mirror is used on hairpin bends, to see the vehicles coming from other side of the bend.