In This Post we are providing Chapter-9 Ray Optics and Optical Instrument NCERT MCQ for Class 12 Physics which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERT MCQ ON RAY OPTICS AND OPTICAL INSTRUMENT
Question 1.
A short pulse of white light is incident from air to a glass slab at normal incidence. After travelling through the slab, the first color to emerge is
(a) blue.
(b) green.
(c) violet.
(d) red.
Answer: (d) red.
Question 2.
You are given four sources of light each one providing a light of a single color – red, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90°. Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of incidence?
(a) The beam of red light would undergo total internal reflection.
(b) The beam of red light would bend towards normal while it gets refracted through the second medium.
(c) The beam of blue light would undergo total internal reflection.
(d) The beam of green light would bend away from the normal as it gets refracted through the second medium.
Answer: (c) The beam of blue light would undergo total internal reflection.
Question 3.
The optical density of turpentine is higher than that of water while its mass density is lower. Figure shows a layer of turpentine floating over water in a container. For which one of the four rays incident on turpentine in figure, the path shown is correct?
(a) 1.
(b) 2
(c) 3
(d) 4
Answer: (b) 2
Question 4.
There are certain material developed in laboratories which have a negative refractive index (figure). A ray incident from air (medium 1) into such a medium (medium 2) shall follow a path given by
Answer: (a)
Question 5.
Consider an extended object immersed in water contained in a plane trough. When seen from close to the edge of the trough the object will not look distorted because
(a) the apparent depth of the points close to the edge are nearer the surface of the water compared to the points away from the edge.
(b) the angle subtended by the image of the object at the eye is smaller than the actual angle subtended by the object in air.
(c) some of the points of the object far away from the edge may not be visible because of total internal reflection.
(d) water in a trough acts as a lens and magnifies the object.
Answer: (d) water in a trough acts as a lens and magnifies the object.
Question 6.
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (figure). When observed from the face AD, the pin shall
(a) appear to be near A.
(b) appear to be near D.
(c) appear to be at the center of AD.
(d) not be seen at all.
Answer: (d) not be seen at all.
Question 7.
An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. Which one of the following is not possible?
(a) The length of the telescope tube is 20.02 m.
(b) The magnification is 1000.
(c) The image formed is inverted.
(d) An objective of a larger aperture will increase the brightness and reduce chromatic aberration of the image.
Answer: (d) An objective of a larger aperture will increase the brightness and reduce chromatic aberration of the image.
Question 8.
An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be:
(a) 30 cm away from the mirror
(b) 36 cm away from the mirror
(c) 30 cm towards the mirror
(d) 36 cm towards the mirror
Answer: (b) 36 cm away from the mirror
Question 9.
The refractive index of the material of a prism is √2 and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is:
(a) 60°
(b) 45°
(c) 30°
(d) zero
Answer: (b) 45°
Question 10.
A diverging lens with magnitude of focal length 25 cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm. A beam of parallel light falls on the diverging lens. The final image formed is:
(a) real and at a distance of 40 cm from the divergent lens
(b) real and at a distance of 6 cm from the convergent lens
(c) real and at a distance of 40 cm from convergent lens
(d) virtual and at a distance of 40 cm from convergent lens.
Answer: (c) real and at a distance of 40 cm from convergent lens
Question 11.
The bouncing back of light when it strikes a smooth or polished surface is called …………….. of light.
(a) Refraction
(b) Reflection
(c) Dispersion
(d) Divergence
Answer: (b) Reflection
Question 12.
When light is reflected from a polit, surface the angle of incidence is …………… to the angle of reflection.
(a) Equal
(b) Same
(c) Different
(d) zero
Answer: (a) Equal
Question 13.
The image formed by a plane mirror shows …………….. inversion.
(a) Incident
(b) Parallel
(c) Transverse
(d) Lateral
Answer: (d) Lateral
Question 14.
A plane drawn perpendicular to the principal axis and passing through the principal focus is called ………………. plane.
(a) Focal
(b) Principal focus
(c) Optical center
(d) Optical axis
Answer: (a) Focal
Question 15.
The size of the mirror is called its …………………..
(a) Axis
(b) Focal
(c) Principal axis
(d) Aperture
Answer: (d) Aperture
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