Mirrors and Images MCQ Quiz - Objective Question with Answer for Mirrors and Images - Download Free PDF

Calculation:

A real, inverted image is possible only if the object is placed beyond the focus, i.e., x > f.

If x = 2f, then the image and object are at equal distances, and no parallax is seen.

Here, when the eye is moved leftward, and the image appears to move to the right, it implies that the image lies farther from the mirror than the object pin.

This parallax effect confirms the object is between the focal length and center of curvature.

Correct Answer: Option B

Explanation:

A plane mirror forms an image with the following characteristics:

• The image is virtual and erect (option B).

• The image is laterally inverted (option D).

• The image is same size as the object, not smaller (so option C is incorrect).

Therefore, the correct answer is: Option B and D only.

\(m=\pm 3\) and \(f=-6\ cm\)

Now \(m=\dfrac{f}{f-u}\Rightarrow \pm 3=\dfrac{-6}{-6-u}\)

For real image \(-3=\dfrac{-6}{-6-u}\Rightarrow u=-8\ cm\)

For virtual image \(3=\dfrac{-6}{-6-u}\Rightarrow u=-4\ cm\)

The correct answer is Principal focus.

Key Points

• Rays move parallel to the principal axis of a convex lens after refraction passes through the principal focus.
• All the cases for the ray of light emanating from the source and refracting through a convex lens are shown in the table:
  ​

Additional Information

• The transparent curved surface is used to refract the light and make an image of any object placed in front of it is called a lens.
• The lens whose refracting surface is upside is called a convex lens.
• The convex lens is also called a converging lens.
• The lens having refracting surface inward is called a concave lens.
• The concave lens is also called a diverging lens.

CONCEPT:

Types of Mirrors and Image Formation

• Plane Mirror: Always forms virtual, erect, and same-sized images.
• Concave Mirror:
  • Forms real, inverted images when the object is placed beyond the focal point.
  • Can form enlarged images if the object is placed between the focal point and the center of curvature.
• Convex Mirror: Forms virtual, erect, and diminished images.

EXPLANATION:

• A (Nature: virtual and erect, Size: same as object): Plane mirror fits this description.
• B (Nature: real and inverted, Size: same as object): A concave mirror with the object at the center of curvature forms this type of image.
• C (Nature: real and inverted, Size: enlarged): A concave mirror with the object placed between the focal point and the center of curvature fits this description.
• D (Nature: virtual and erect, Size: diminished): A convex mirror fits this description.

Conclusion:-

• So, the correct answer is A - Plane mirror, B - Concave, C - Concave, D - Convex

The correct answer is Real and inverted.

• The image formed by the concave mirror when the object is placed beyond the center of curvature is Real and Inverted.

Key Points

• Concave Mirror:
  • A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the center of the sphere, is called a concave mirror.
  • Concave mirrors are commonly used in  Torches, Search-lights, Vehicle headlights, Shaving mirrors, Microscopes, and Telescopes.
  • Image formation by a concave mirror for different positions of the object:

CONCEPT:

• Plane Mirror: A plane mirror is a mirror with a flat (planar) reflective surface.

The characteristics of an image formed in a plane mirror:

• The image formed by the plane mirror is virtual and erect i.e. image cannot be projected or focused on a screen.
• The distance of the image ‘behind’ the mirror is the same as the distance of the object in front of the mirror.
• The size of the image formed is the same as the size of the object.
• The image is laterally inverted, i.e. left hand appears to be right hand when seen from the plane mirror.

• If the object moves towards (or away from) the mirror at a certain rate, the image also moves towards (or away from) the mirror at the same rate.

EXPLANATION:

From the above discussion, we can say that,

• The image formed by Plane Mirror is always Virtual and Erect. So option 1 is correct.
• A convex lens and a concave mirror forms both real and virtual images.
• A concave lens and a convex mirror can form only virtual images.

The correct answer is at the centre of the curvature.

Key Points

Position of the Object at the Centre of Curvature: 
When an object is placed at the center of curvature (C) of a concave mirror, the object is essentially at a distance equal to the radius of curvature from the mirror's pole.
Formation of Image:

• In this scenario, the reflected rays from the object converge and meet at the center of curvature.
• The image formed is real because the reflected rays actually converge at a point.
• The image is inverted because the reflected rays cross over at the center of curvature, resulting in an inverted orientation.
• The image is of the same size as the object because the distance from the object to the mirror is the same as the distance from the image to the mirror.

• If an object is placed at the centre of curvature of a concave mirror, then the image formed is real, inverted, and of the same size as that of the object.

The correct answer is ​to Remain unchanged.

• In the case of mirrors, for both concave and convex the focal length shall remain unchanged for the mirrors when immersed in water.

Key Points

• This is because the property of the mirror i.e. the focal length of mirrors does not depend on the external medium in which it is held.
• However, for lenses, refraction takes place when the lens is immersed in water.
• Since the value for the refractive index for air (1.0003) is less than that of water (1.3333) its focal length would increase.

CONCEPT:

Concave mirror: 

• If the inner surface of the spherical mirror is the reflecting surface, then it is called a concave mirror. It is also called a focusing mirror/converging mirror.
• • The size of the image produced by these mirrors can be larger or smaller than the object, depending upon the distance of the object from the mirror.
  • The concave mirror can form both real as well as virtual images of any object.

Sign convention in mirrors

• All distance are measured from the pole of the mirror.
• The distance measured from the pole (p) to the left side of the mirror is taken as negative.
• The distance measured from the pole (p) to the right side of the mirror is taken as positive.
• The heights measured upwards and perpendicular to the principal axis of the mirror is taken as positive.
• The heights measured downwards and perpendicular to the principal axis of the mirror is taken as negative.

​EXPLANATION:

Given - Radius of curvature (R) = - 30 cm

• The relationship between the focal length (f) and the radius of curvature (R) is given by -

\(\Rightarrow f = \frac{R}{2}\)

\(\Rightarrow f = \frac{-30}{2}=-15 cm\)

The correct answer is Option 3.

CONCEPT:

Different positions of the object and their image by a concave mirror: 

EXPLANATION:

• An object is placed in front of a concave mirror at a point between its curvature and focus. The image will be formed at a point beyond the center of curvature. So option 3 is correct.​

Important Points

CONCEPT:

• Concave mirror:
  • If a curved glass is painted outside, then the inner part becomes reflecting called a concave mirror.
  • A image is given below with the ray diagram of the concave mirror.

EXPLANATION:

• An object placed at the center of curvature of the concave mirror
  • The image formed at the center of curvature.
  • The image is inverted.
  • Real and same size image is formed.

CONCEPT:

• Concave mirror: The mirrors curved inside on the reflecting side are called concave mirrors.
  • These mirrors produce a real as well as virtual images, inverted and erect, and magnified as well as the diminished image of the object.
  • Thes are used in reflecting telescopes, shaving mirrors, and ophthalmoscope. It is also used as a reflector for the headlights of a vehicle and searchlights.
• Convex mirror: It is an outward curved mirror that produces a diminished image.
  • Convex mirrors either diverge a parallel beam of light into all directions or gather light from all directions and produce a parallel beam out of it.

EXPLANATION:

• In the case of the concave mirror, when the object is between the focus and the pole, image formed is virtual, erect, and enlarged. That's why concave mirror is used as a shaving glass. So option 1 is correct.

CONCEPT:

• Concave mirror: The mirrors curved inside on the reflecting side are called concave mirrors.
  • These mirrors produce real as well as virtual images, inverted and erect, and magnified as well as the diminished image of the object.
  • These are used in reflecting telescopes, shaving mirrors, and ophthalmoscopes. It is also used as a reflector for the headlights of a vehicle and searchlights.
• Convex mirror: It is an outward curved mirror that produces a diminished image.
  • Convex mirrors either diverge a parallel beam of light into all directions or gather light from all directions and produce a parallel beam out of it.

EXPLANATION:

• In the case of the concave mirror, when the object is between the focus and the pole, the image formed is virtual, erect, and enlarged. That's why a concave mirror is used as a shaving glass. So option 2 is correct.

CONCEPT:

• Convex mirror: It is an outward curved mirror that produces a diminished image.
  • Convex mirrors either diverge a parallel beam of light into all directions or gather light from all directions and produce a parallel beam out of it.

• Focal length (f): The distance between the centre of the mirror and the focal point (where parallel rays of light meet or appear to meet) of the mirror is called the focal length.
• The radius of curvature (R): The distance between the centre of the lens or mirror to the vertex which is located on the local optical axis is called the Radius of Curvature.
• The focal length is half of the radius of curvature.

f = R/2

CALCULATION:

Given that:

Radius of curvature (R) = 30 cm,

The focal length (f) = R/2 = 30/2 = 15 cm