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Science M.C.Q-[Phy-1M]

Reflection of Light · CBSE STD 10 (CBSE - English Medium). 47 questions.

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M.C.Q-[Phy-1M]

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Question 11 Mark
Whatever be the position of the object, the image formed by a mirror is virtual, erect and smaller than the object. The mirror then must be:
  1. Plane.
  2. Concave.
  3. Convex.
  4. Either concave or convex.
Answer
  1. Convex.

Explanation:

It should be a convex mirror. This is because when an object is in front of a convex mirror, irrespective of its distance, a virtual, erect and diminished image of the object is obtained.

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Question 21 Mark
Two big mirrors A and B are fitted side by side on a wall. A man is standing at such a distance from the wall that he can see the erect image of his face in both the mirrors. When the man starts walking towards the mirrors, he find that the size of his face in mirror A goes on increasing but that in mirror B remains the same.
  1. Mirror A is concave and mirror B is convex.
  2. Mirror A is plane and mirror B is concave.
  3. Mirror A is concave and mirror B is plane.
  4. Mirror A is convex and mirror B is concave.
Answer
  1. Mirror A is concave and mirror B is plane

Explanation:

Image formed by a plane mirror is virtual, erect and of the same size as the object.Image formed by a concave mirror is virtual, erect and larger than the object.

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Question 31 Mark
The real image formed by a concave mirror is smaller than the object if the object is:
  1. Between centre of curvature and focus.
  2. At a distance greater than radius of curvature.
  3. At a distance equal to radius of curvature.
  4. At a distance equal to focal length.
Answer
  1. At a distance greater than radius of curvature.

Explanation:

The reason being, the image formed by a concave mirror is virtual, erect and magnified. The position of the object is between the pole and the focus.

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Question 41 Mark
The real image formed by a concave mirror is larger than the object when object is:
  1. At a distance equal to radius of curvature.
  2. At a distance less than the focal length.
  3. Between focus and centre of curvature.
  4. At a distance greater than radius of curvature.
Answer
  1. Between focus and centre of curvature.

Explanation:

For an object placed between the focus and the centre of curvature, the real image formed by a concave mirror is larger than the object.

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Question 51 Mark
The mirror which can form a magnified image of an object is:
  1. Convex mirror.
  2. Plane mirror.
  3. Concave mirror.
  4. Both convex and concave mirror.
Answer
  1. Concave mirror

Explanation:

A concave mirror forms a magnified image of an object.

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Question 61 Mark
The mirror used by a dentist to examine the teeth of a person is:
  1. Convex.
  2. Concave.
  3. Plane.
  4. Any one of the above.
Answer
  1. Concave.

Explanation:

A concave mirror is used by a dentist to examine the teeth of a person.

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Question 71 Mark
The image of an object formed by a plane mirror is:
  1. Virtual.
  2. Real.
  3. Diminished.
  4. Upside-down.
Answer
  1. Virtual.

Explanation:

The reason being, the image cannot be projected on a screen.

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Question 81 Mark
The image formed by a spherical mirror is virtual. The mirror will be:
  1. Concave.
  2. Convex.
  3. Either concave or convex.
  4. Metallic.
Answer
  1. Convex.

Explanation:

A convex mirror always forms a virtual image.

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Question 91 Mark
The 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.
Answer
  1. Virtual, behind the mirror and of the same size as the object.

Explanation:

The image formed by a plane mirror is virtual, behind the mirror and of the same size because it cannot be projected on a screen.

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Question 101 Mark
The image formed by a concave mirror is virtual, erect and magnified. The position of object is:
  1. At focus.
  2. Between focus and centre of curvature.
  3. At pole.
  4. Between pole and focus
Answer
  1. Between focus and centre of curvature.

Explanation:

The reason being, the image formed by a concave mirror is virtual, erect and magnified. The position of the object is between the pole and the focus.

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Question 111 Mark
The image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be:
  1. At the focus.
  2. Between the centre of curvature and focus.
  3. At the centre of curvature.
  4. Beyond the centre of curvature.
Answer
  1. At the centre of curvature

Explanation:

The reason being, the image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be at the centre of curvature.

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Question 121 Mark
The image formed by a concave mirror is real, inverted and highly diminished (much smaller than the object). The object must be:
  1. Between pole and focus.
  2. At focus.
  3. At the centre of curvature.
  4. At infinity.
Answer
  1. At infinity.

Explanation:

The reason being, the image formed by a concave mirror is real, inverted and highly diminished (much smaller than the object). Therefore, the object must be at infinity.

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Question 131 Mark
The focal length of a spherical mirror of radius of curvature 30cm is:
  1. 10cm
  2. 15cm
  3. 20cm
  4. 30cm
Answer
  1. 15cm

Explanation:

The focal length of a spherical mirror is half of its radius of curvature.

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Question 141 Mark
The focal length of a small concave mirror is 2.5cm. In order to use this concave mirror as a dentist's mirror, the distance of tooth from the mirror should be:
  1. 2.5cm
  2. 1.5cm
  3. 4.5cm
  4. 3.5cm
Answer
  1. 1.5cm

Explanation:

When an object is placed between the pole and the focus of a concave mirror, an enlarged image is formed.

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Question 151 Mark
The figure given alongside shows the image of a clock as seen a plane mirror. The correct time is:
Figure.
  1. 2.25
  2. 2.35
  3. 6.45
  4. 9.25
Answer
  1. 9.25

Explanation:

since the image formed by a plane mirror is laterally inverted.

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Question 161 Mark
The angle of reflection is equal to the angle of incidence:
  1. Always.
  2. Sometimes.
  3. Under special conditions.
  4. Never.
Answer
  1. Always.

Explanation:

In accordance with the first law of reflection, which states that the angle of reflection is equal to the angle of incidence.

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Question 171 Mark
The angle of incidence for of light passing through the centre of curvature of a concave mirror is:
  1. 45°
  2. 90°
  3. 0°
  4. 180°
Answer
  1. 0°

Explanation:

The reason being, a ray of light passing through the centre of curvature of a concave mirror strikes the mirror normally or perpendicularly.

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Question 181 Mark
The angle between an incident ray and the plane mirror is 30°. The total angle between the incident ray and reflected ray will be:
  1. 30°
  2. 60°
  3. 90°
  4. 120°
Answer
  1. 120°

Explanation:

Since, angle of incidence = 90° - angle between plane mirror and incident ray = 90° - 30° = 60° and according to first law of reflection, angle of incidence = angle of reflection = 60°

Total angle between incident ray and reflected ray = 60° + 60° = 120° 

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Question 191 Mark
One of the following does not apply to a concave mirror. This is:
  1. Focal length is negative.
  2. Image distance can be positive or negative.
  3. Image distance is always positive.
  4. Height of image can be positive or negative.
Answer
  1. Image distance is always positive.

Explanation:

The image distance is always positive with the exception of one case, when the object is placed between the pole and the focus. In all other cases, the image is formed in front of the mirror and on the left side.

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Question 201 Mark
n order to obtain a magnification of, −0.6 (minus 0.6) with a concave mirror, the object must be placed:
  1. At the focus.
  2. Between pole and focus.
  3. Between focus and centre of curvature.
  4. Beyond the centre of curvature.
Answer
  1. Beyond the centre of curvature.

Explanation:

In order to obtain a magnification of −0.6 (minus 0.6) with a concave mirror, the object needs to be placed beyond the centre of curvature, as at this point a diminished image will be formed.

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Question 211 Mark
Magnification produced by a plane mirror is:
  1. Less than one.
  2. Greater than one.
  3. Zero.
  4. Equal to one.
Answer
  1. Equal to one.

Explanation:

Magnification produced by a plane mirror is equal to one. This is because the size of the image formed by a plane mirror is same as the size of the object.

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Question 221 Mark
Magnification produced by a convex mirror is always:
  1. More than 1.
  2. Less than 1.
  3. Equal to 1.
  4. More or less than 1.
Answer
  1. Less than 1.

Explanation:

Magnification produced by a convex mirror is always less than 1. This is because the size of the image formed by a convex mirror is smaller than the object.

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Question 231 Mark
Linear magnification produced by a concave mirror may be:
  1. Less than 1 or equal to 1.
  2. More than 1 or equal than 1.
  3. Less than 1, more than 1 or equal to 1.
  4. Less than 1 or more than 1.
Answer
  1. Less than 1, more than 1 or equal to 1.

Explanation:

Magnification, $\text{m}=\frac{\text{v}}{\text{u}}$

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Question 241 Mark
Linear magnification (m) produced by a rear view mirror fitted in vehicles:
  1. Is equal to one.
  2. Is less than one.
  3. Is more than one.
  4. In be more less than one depending on the position of object.
Answer
  1. Is less than one.

Explanation:

Linear magnification (m) produced by a rear view mirror, installed in vehicles, is less than one.

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Question 251 Mark
In the concave reflector of a torch, the bulb is placed:
  1. Between the pole and focus of reflector.
  2. At the focus of reflector.
  3. Between focus and centre of curvature of reflector.
  4. At the centre of curvature of reflector.
Answer
  1. At the focus of reflector.

Explanation:

When a light bulb is placed at the focus of a concave mirror reflector, the diverging light rays of the bulbare collected by the reflector and then reflected, to produce a strong, parallel-sided beam of light.

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Question 261 Mark
In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed:
  1. Between pole and focus.
  2. Between focus and centre of curvature.
  3. At the centre of curvature.
  4. Beyond the centre of curvature.
Answer
  1. Between focus and centre of curvature.

Explanation:

In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed between the focus and the centre of curvature.

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Question 271 Mark
In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16cm, the object will have to be placed at a distance.
  1. Between 6cm and 16cm
  2. Between 32cm and 16cm
  3. Between 48cm and 32cm
  4. Beyond 64cm
Answer
  1. Between 32cm and 16cm

Explanation:

To obtain a magnification of -1.5, the object needs to be placed between the focus and the centre of curvature.

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Question 281 Mark
In a convex spherical mirror, reflection of light takes place at:
  1. A flat surface.
  2. A bent-in surface.
  3. A bulging-our surface.
  4. An uneven surface.
Answer
  1. Abulging-out surface.

Explanation:

In a convex spherical mirror, reflection of light takes place at the bulged-out surface.

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Question 291 Mark
If the image formed is always virtual, the mirror can be:
  1. Concave or convex.
  2. Concave or plane.
  3. Convex or plane.
  4. Only convex.
Answer
  1. Convex or plane.

Explanation:

Both convex and plane mirrors always form virtual images.

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Question 301 Mark
If the focal length of a spherical mirror is 12.5cm, its radius of curvature will be:
  1. 25cm
  2. 15cm
  3. 20cm
  4. 35cm
Answer
  1. 25cm

Explanation:

Radius of curvature 'R' = 2f

 R = 2 × 12.5

= 25cm

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Question 311 Mark
If R is the radius of curvature of a spherical mirror and f is its focal length, then:

  1. R = f

  2. R = 2

  3. $\text{R}=\frac{\text{f}}{2}$

  4. R = 3f

Answer
  1.  R = 2f

Explanation:

If R is the radius of curvature of a spherical mirror and f is its focal length, then R = 2f.

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Question 321 Mark
If a magnification of, −1 (minus one) is to be obtained by using a converging mirror, then the object has to be placed:
  1. Between pole and focus.
  2. At the centre of curvature.
  3. Beyond the centre of curvature.
  4. At infinity.
Answer
  1. At the centre of curvature.

Explanation:

If a magnification of −1 (minus one) is to be obtained by using a converging mirror, the object needs to be placed at the centre of curvature so that an image of same size as the object can be formed.

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Question 331 Mark
Consider two statements A and B given below:
  1. Real image is always inverted.
  2. Virtual image is always erect.
Out of these two statements:
  1. Only A is true.
  2. Only B is true.
  3. Both A and B are true.
  4. None is true.
Answer
  1. Both A and B are true.

Explanation:

A real image is always inverted and a virtual image is always erect.

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Question 341 Mark
A virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12cm. Which of the following object distance should be chosen for this purpose?
  1. 10cm
  2. 15cm
  3. 20cm
Give reason for your choice
Answer
  1. 10cm

Explanation:

The object must be kept at a distance of 10cm from the concave mirror in order to produce a virtual, erect and magnified image. The reason being, a concave mirror forms a virtual, erect and magnified image when an object is placed between the focus and the pole

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Question 351 Mark
A real image of an object is to be obtained. The mirror required for this purpose is:
  1. Convex.
  2. Concave.
  3. Plane.
  4. Either convex or concave.
Answer
  1. Concave.

Explanation:

A concave mirror forms a real image of an object.

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Question 361 Mark
A ray of light strikes a plane mirror PQ at an angle of incidence of 30°, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is:
  1. 30°
  2. 45°
  3. 60°
  4. 90°
Draw a ray-diagram to illustrate your answer.
Answer
  1. 60°.

Explanation:



Here.

$\angle\text{A}\text{B}\text{N}= \angle\text{N}\text{B}\text{C}$ (angle of incidence = angle of reflection) 

$\angle\text{B}\text{C}\text{O}=\angle\text{N}\text{B}\text{C}$ (alternate angles)

$\angle\text{M}\text{C}\text{B}=90^\circ-\angle\text{B}\text{C}\text{O}$ $\big(\angle\text{M}\text{C}\text{B}=$angle of incident for mirror QR$\big) $

= 60°

Now

$\big($$\angle\text{M}\text{C}\text{B}=\angle\text{M}\text{C}\text{D}=60^\circ $angle of reflection from mirror QR and angle of incidence = angle of reflection$\big)$

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Question 371 Mark
A ray of light is incident on a plane mirror making an angle of 90° with the mirror surface. The angle of reflection for this ray of light will be:
  1. 45°
  2. 90°
  3. 0°
  4. 60°
Answer
  1. 0°

Explanation:

Angle of incidence = 0°

According to the first law of reflection, the angle of incidence is equal to the angle of reflection.

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Question 381 Mark
An object is placed at the following distances from a concave mirror of focal length 15cm, turn by turn:
  1. 35cm
  2. 30cm
  3. 20cm
  4. 10cm
Which position of the object will produce:
  1. A magnified real image?
  2. A magnified virtual image?
  3. A diminished real image?
  4. An image of same size as the object?
Answer
Here, radius of curvature = 2 × focal length = 2 × 15cm = 30cm
  1. At position (c), i.e., 20cm from the concave mirror, the image formed will be magnified and real. The reason being, a real and magnified image is formed by the concave mirror when an object is placed between the focus and the centre of curvature.
  2. At position (d), i.e., 10cm from the concave mirror, the image formed will be magnified and virtual. The reason being, a virtual and magnified image is formed by the concave mirror when an object is placed between the focus and the pole.
  3. At position (a), i.e., 35cm from the concave mirror, the image formed will be diminished and real. The reason being, a diminished and real image is formed by the concave mirror when an object is placed beyond the centre of curvature.
  4. At position (b), i.e., 30cm from the concave mirror, the image formed will be of the same size as the object. The reason being, an image of the same size as the object is formed by the concave mirror when the object is placed at the centre of curvature.
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Question 391 Mark
An object is placed at a large distance in front of a concave mirror of radius of curvature 40cm. The image will be formed in front of the mirror at a distance:
  1. 20cm
  2. 30cm
  3. 40cm
  4. 50cm
Answer
  1. 20cm

Explanation:

An object is placed at a large distance but in front of a concave mirror with a radius of curvature of 40cm. The image of this object will be formed at the focus that is 20cm away

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Question 401 Mark
An object is placed 20cm in front of a plane mirror. The mirror is moved 2cm towards the object. The distance between the positions of the positions of the original and final images seen in the mirror is:
  1. 2cm.
  2. 4cm.
  3. 10cm.
  4. 22cm
Answer
  1. 4cm.

Explanation:

Distance between original image and final image = distance the mirror moved + same distance the image moved = 2 + 2 = 4c.

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Question 411 Mark
An object is 100mm in front of a concave mirror which produces an upright (erect image). The radius of curvature of the mirror is:
  1. Less than 100mm.
  2. Between 100mm and 200 mm.
  3. Exactly 200mm.
  4. More than 200mm
Answer
  1. More than 200mm

Explanation:

The reason being, a concave mirror forms an erect image when an object is placed between the focus and the pole. Further, the radius of curvature is twice the distance between the focus and the pole. This gives a radius of curvature greater than 200mm.

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Question 421 Mark
A diverging mirror is:
  1. A plane mirror.
  2. A convex mirror.
  3. A concave mirror.
  4. A shaving mirror
Answer
  1. A convex mirror

Explanation:

A convex mirror diverges the rays of light incident on it; hence, it acts as a diverging mirror.

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Question 431 Mark
A concave mirror produces magnification of +4. The object is placed:
  1. At the focus.
  2. Between focus and centre of curvature.
  3. Between focus and pole.
  4. Between the centre of curvature.
Answer
  1. Between focus and pole.

Explanation:

A concave mirror produces a magnification of +4 when the object is placed between the focus and the pole.

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Question 441 Mark
A concave mirror has a focal length of 25cm. At which of the following distance should a person hold his face from this concave mirror so that it may act as a shaving mirror?
  1. 45cm
  2. 20cm
  3. 25cm
  4. 30cm
Give reason for your choice.
Answer
  1. 20cm

Explanation:

A person must hold his face at a distance of 20cm, away from the concave mirror. A concave mirror forms an erect, virtual and magnified image when an object is placed between the focus and the pole. Therefore, it acts as a shaving mirror.

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Question 451 Mark
A concave mirror cannot be used as:
  1. A magnifying mirror
  2. A torch reflector
  3. A dentist's mirror
  4. A real view mirror
Answer
  1. A real view mirror

Explanation:

A concave mirror cannot be used as a rear view mirror because it forms inverted images of distant objects.

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Question 461 Mark
According to New Cartesian Sign Convention:
  1. Focal length of concave mirror is positive and that of convex mirror is negative.
  2. Focal length of both concave and convex mirrors is positive.
  3. Focal length of both concave and convex mirrors is negative.
  4. Focal length of concave mirror is negative and that of convex mirror is positive.
Answer
  1. The focal length of a concave mirror is negative and that of a convex mirror is positive.

Explanation:

This is because the focus of a concave mirror is in front of the mirror, on the left side, and the focus of a convex mirror is behind the mirror, on the right side.

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Question 471 Mark
A boy is standing in front of and close to a special mirror. He finds the image of his head bigger than normal, the middle part of his body of the same size, and his legs smaller than normal. The special mirror is made up of three types of mirrors in the following order from top downwards:
  1. Convex, Plane, Concave.
  2. Plane, Convex, Concave.
  3. Concave, Plane, Convex.
  4. Convex, Concave, Plane.
Answer
  1. Concave, Plane, Convex.

Explanation:

  • Concave: A concave mirror forms an image larger than the object.
  • Plane: A convex mirror forms an image smaller than the object.
  • Convex: A plane mirror forms an image similar to the size of the object.
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M.C.Q-[Phy-1M] - Science STD 10 Questions - Vidyadip