# Physics Class 12 MCQ Ray Optics And Optical Instruments – Chapter 9

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Most of the students find Optics as a difficult unit in Physics. Now to understand it better, it is very important that you practice a lot of questions from the unit, so that the things would start getting clarified in your mind. You can make this as a scoring unit, if you keep on practicing questions, revising theory part from this unit.

Here we have provided you with some important questions of Ray Optics And Optical Instruments Chapter 9. You may scroll down the page and start practicing these CBSE 12th MCQs With Solutions of Ray Optics And Optical Instruments Chapter 9 Physics. Practice these Ray Optics And Optical Instruments MCQs and get good grades in your board examinations.

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## Physics Class 12 MCQ Ray Optics And Optical Instruments – Chapter 9

#### Ques 1: The correct mirror equation is

• 1/f = 1/v + 1/u
• 1/f = 1/v – 1/u
• 1/f = 1/u – 1/v
• none of these

1/f = 1/v + 1/u

#### Ques 2: Image of an object in a concave mirror is

• always real
• always negative
• always erect
• real or virtual depending on position of object

real or virtual depending on position of object

#### Ques 3: The linear magnification of a convex mirror is

• always positive
• always negative
• sometimes positive and sometimes negative
• cannot predict

always positive

#### Ques 4: An object is held in front of a concave mirror between F and C. The image formed is

• at F
• at C
• beyond C
• none of the above

beyond C

### Ray Optics and Optical Instruments Class 12 MCQs Questions with Solutions

• 6000 Å
• <6000 Å
• >6000 Å
• cannot say

6000 Å

#### Ques 6: Refractive index of glass w.r.t. water is 9/8. What is the speed of light in water? Given speed of light in glass is 2 × 108 m/s.

• 2 × 108
• 3 × 108 m/s
• 2.25 × 108 m/s
• none of these

2.25 × 108 m/s

• 1 cm
• 2 cm
• 3 cm
• 1.33 cm

1.33 cm

#### Ques 8: Optical fibres are based on the phenomenon of

• reflection
• refraction
• dispersion
• total internal reflection

total internal reflection

#### Ques 9: The focal length of a double convex lens is equal to radius of curvature of either surface. The refractive index of its material is

• 3/2
• 1
• 4/3
• none of these

3/2

• 20 cm
• 40 cm
• 60 cm

40 cm

### Class 12 Physics MCQs Of Ray Optics And Optical Instruments Chapter 9

#### Ques 11: In vacuum, which colour travels fastest?

• red
• violet
• yellow
• all colours have the same velocity

all colours have the same velocity

• μ-1/A
• A/μ-1
• (μ-1)A
• noe of these

(μ-1)A

#### Ques 13: The relation between angle of incidence i, angles of prism A and angle of minimum deviation for a triangular prism is

• i = a + δm
• i = A + δm / m
• δm = i + A
• δm = i-A

i = A + δm / m

#### Ques 14: One cannot see through fog, because

• fog absorbs the light
• light suffers total reflection at droplets
• refractive index of fog is infinity
• light is scattered by droplets

light is scattered by droplets

• √3
• √2
• 3/2
• 2/3

3/2

#### Ques 16: The lens used for correcting myopia is

• concave
• convex
• plano concave
• none of these

concave

• fixed
• variable
• infinite
• 1 metre

fixed

### Important MCQs for CBSE 12 Physics Chapter 9 Ray Optics and Optical Instruments

#### Ques 18: The final image in an astronomical telescope (s.r.t. object) is

• virtual and erect
• real and erect
• real and inverted
• virtual and inverted

virtual and inverted

• 25 cm
• -50 cm
• 50 cm
• -25 cm

-50 cm

#### Ques 20: An astronomical telescope has a magnifying power of 10. In normal adjustment, distance between the objective and eye piece is 22 cm. The focal length of objective lens is

• 10 cm
• 22 cm
• 20 cm
• 2 cm

20 cm #### Ques 21: How does the focal length of a convex lens change if mono chromatic red light is used instead of violet light ?

• Focal length is increased when red light is used
• Focal length remains same when red light is used
• Focal length remains same when red light is used
• Not depends on color of light

Focal length is increased when red light is used

#### Ques 22: A glass lens is immersed in water. What will be the effect on the power of lens ?

• increase
• decrease
• constant
• not depends

decrease #### Ques 23: How does the magnifying power of a telescope change on increasing the linear diameter of its objective?

• Power increases on increasing diameter
• Power decreases on increasing diameter
• Power remains constant on increasing diameter
• Power doesn’t depend on diameter

Power doesn’t depend on diameter

• +1, ∞
• + 1, 0
• -1, ∞
• -1,0

+1, ∞

#### Ques 25: An object approaches a convergent ens from the left of the lens with a uniform speed 5 m/s and stops at the focus. The image

• moves away from the lens with a uniform speed 5 m/s
• moves away from the lens with a uniform acceleration.
• moves away from the lens with a non-uniform acceleration.
• moves towards the lens with a non-uniform acceleration.

moves away from the lens with a non-uniform acceleration.

#### Ques 26: The objective of an astronomical telescope has a large aperture to:

• increase span of observation
• have low dispersion
• reduce spherical aberration
• have high resolution

have high resolution

### Physics MCQs Ray Optics and Optical Instruments

• doubled
• one fourth
• halved
• unaffected

halved

#### Ques 28: Optical fibres are based on the phenomenon of

• reflection
• refraction
• dispersion
• total internal reflection

total internal reflection

#### Ques 29: The characteristic feature of light which remains unaffected on refraction is

• spped
• frequency
• wavelength
• velocity of light

frequency

#### Ques 30: The final image formed in an astronomical telescope with respect to the object is

• real, inverted
• real crect
• virtual erect
• virtual inverted

virtual inverted ## Physics Chapter Wise MCQ Questions and Answers Practice these questions from Ray Optics And Optical Instruments and get an idea about what type of questions could be asked from you from this Chapter Ray Optics And Optical Instruments. We hope you liked the collection of questions. You may drop your reviews and suggestion on the comment box below.

Updated: January 14, 2023 — 6:59 pm