Tag: characteristics of an image formed by a plane mirror

Questions Related to characteristics of an image formed by a plane mirror

A plane mirror:
(i) can form real image of a real object
(ii) neither converges not diverges the rays
(iii) cannot form real image of a real object
Choose the correct option or options.

  1. (i) is correct

  2. (i) and (ii) are correct

  3. (ii) and (iii) are correct

  4. None of the above


Correct Option: C
Explanation:
  • Plane mirrors always produce virtual images, because they never focus light into a single converging point.
  • Hence it does not produce real object or image
  • As power of the plane mirror is zero, hence, it neither converges nor diverges the rays.
  • Hence the option C is the right answer

An object is kept at $60$cm in front of a plane mirror. If the mirror is now moved $25$cm away from the object, how is the image shifted from its previous position?

  1. $25$ cm away

  2. $25$ cm towards

  3. $50$ cm away

  4. $50$ cm towards


Correct Option: C
Explanation:

In this case, the mirror is moved 25 cm away from its initial position. Therefore, if the mirror is moved with distance x, then image in the mirror will move by distance 2x.
That is, 2x=50 cm.
So, the image will shift by 50 cm away from its previous position.

In our houses, we use a _____________ to look at ourselves.

  1. Convex mirror

  2. Concave mirror

  3. Convex lens

  4. Plane mirror


Correct Option: D
Explanation:

In plane mirrors the image formed is of the same size.

Image formed by a plane mirror is 

  1. virtual, behind the mirror and enlarged

  2. virtual, behind the mirror and of the same size as the object

  3. real at the surface of the mirror and enlarged

  4. real, behind the mirror and of the same size as the object.


Correct Option: B
Explanation:

Answer is B.

The image formed by a plane mirror is always virtual (meaning that the light rays do not actually come from the image), upright, and of the same shape and size as the object it is reflecting. A virtual image is a copy of an object formed at the location from which the light rays appear to come.
To summarize, the image formed by plane mirrors are,
1. Virtual 
2. Behind the mirror 
3. Erect (means not inverted) 
4. Same size as the object 
5. At same distance from the mirror as the object is from the mirror.

Fill in the blank:

________ are used in periscopes to reflect light.

  1. Concave mirrors

  2. Convex mirrors

  3. Plane mirrors

  4. Convex lenses


Correct Option: C
Explanation:

Two plane mirrors are placed parallel in a periscope to reflect light. 

What type of image is formed by a plane mirror ?

  1. Upright

  2. Magnified

  3. inverted

  4. all of these


Correct Option: A
Explanation:

Images formed by plane mirrors are virtual, upright, left-right reversed, the same distance from the mirror as the object's distance, and the same size as the object.

A virtual image is always erect. 

  1. True

  2. False


Correct Option: A
Explanation:

An image, such as that seen in a mirror, in which the rays of light appear to be emanating from some object that is not there is called a virtual image. Virtual images are always erect. They, also, may be either larger or smaller than the object.
Hence, the statement is true.

During normal incidence of light:

  1. angle of incidence is $90^0$

  2. angle of incidence is $0^0$

  3. sum of angle of incidence and angle of reflection is $90^0$

  4. angle of incidence is greater than angle of reflection


Correct Option: B
Explanation:

Angle of incidence and the angle of reflection measured from the normal drawn on the point of incidence.

During normal incidence the light is incident along the normal on the point of incidence.
So, angle of incidence is $0^0$.

An object is placed 15 cm from a diverging mirror, of radius of curvature 20 em. What is the image magnification produced?

  1. +0.4

  2. -0.4

  3. +2

  4. -2


Correct Option: D
Explanation:

Answer is D.

For a spherically curved mirror in air, the magnitude of the focal length is equal to the radius of curvature of the mirror divided by two. The focal length is positive for a concave mirror.
Therefore, the focal length of the mirror is 20 cm / 2 = 10 cm.
The mirror equation expresses the quantitative relationship between the object distance (do), the image distance (di), and the focal length (f). The equation is stated as follows:
1/f = 1/do + 1/di
So, 1/di = 1/f - 1/do = 1/10 - 1/15
Therefore, di = 30 cm.
The magnification equation relates the ratio of the image distance and object distance to the ratio of the image height (hi) and object height (ho). The magnification equation is stated as follows:
M = hi / ho = -(di / do) = -(30 / 15) = -2.
Hence, the image magnification produced is -2.

A person looks into the mirror by placing it close to his face. The image of his face was erect, laterally inverted and of the same size. Then, the mirror must be :

  1. plane

  2. concave

  3. convex

  4. plane or concave


Correct Option: A
Explanation:

The nature of the image formed by a plane mirror is virtual, erect, of the same size and also laterally inverted