83 free MCQs on Ray Optics and Optical Instruments, each with its own worked answer and explanation. Reflection, refraction, lenses, mirrors, total internal reflection.
Take the timed Ray Optics and Optical Instruments chapterwise test →83 practice questions on Ray Optics and Optical Instruments, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Ray Optics and Optical Instruments notes.
Concave mirror ray construction: a ray parallel to the axis reflects through F, and a ray through F reflects parallel, locating the inverted real image. Image: Maxmath12, CC0, via Wikimedia Commons.
Q1.
The refractive index of a transparent medium is 1.5. The speed of light in that medium is:
Q2.
The image formed by a convex mirror of an object placed in front of it is always:
Q4.
When a ray of light passes from a denser medium into a rarer medium, it bends:
Q5.
A real image differs from a virtual image in that a real image:
Q6.
The focal length of a plane mirror is:
Q7.
Speed of light in vacuum is:
Q8.
Angle of incidence equals angle of reflection is:
Q9.
A concave mirror forms real images when the object is:
Q10.
Focal length of a concave mirror of radius of curvature 20 cm is:
Q11.
The mirror formula is:
Q12.
Refractive index of a medium equals:
Q13.
Total internal reflection occurs when light travels from:
Q14.
Optical fibre works on the principle of:
Q15.
A convex lens forms a virtual image when object is:
Q16.
Power of a convex lens of focal length 20 cm is:
Q17.
Which colour of light has the highest refractive index in glass?
Q18.
The phenomenon of splitting white light into its component colors is called:
Q19.
Virtual, erect, and same-sized image is formed by:
Q20.
Magnification formula for mirrors is:
Q21.
Which mirror is used in vehicle rear-view mirrors?
Q22.
Snell's law states: n<sub>1</sub> sin(theta1) =
Q23.
Mirage (apparent water on road) is caused by:
Q24.
The lens formula is:
Q25.
A concave lens always forms what type of image?
Q26.
The sky appears blue because of:
Q27.
A compound microscope has a total magnifying power of 200. If the objective produces a linear magnification of 25, the angular magnification of the eyepiece is:
Q28.
A magnifying glass (simple microscope) has focal length 5 cm. Its magnifying power when the final image is at the near point (25 cm) is:
Q29.
An astronomical telescope in normal adjustment has an objective of focal length 100 cm and an eyepiece of focal length 5 cm. Its magnifying power is:
Q30.
Object at 30 cm from concave mirror of f=10 cm. Image position:
Q31.
Critical angle for glass-air interface if n<sub>glass</sub> = 1.5:
Q32.
Two thin lenses of focal lengths 10 cm and 20 cm placed in contact. Combined power:
Q33.
A ray enters glass slab at 30 degrees to the normal. n<sub>glass</sub> = 1.5. Angle of refraction:
Q34.
Magnification of a concave mirror = +2. Image is:
Q35.
Lensmaker's equation: 1/f = (n-1)(1/R<sub>1</sub> - 1/R<sub>2</sub>). For plano-convex lens (R<sub>2</sub> = infinity), if n=1.5 and R<sub>1</sub>=20 cm, focal length:
Q36.
Diamond has high refractive index (n=2.4). Critical angle for diamond-air is:
Q37.
An object is 20 cm from a convex lens of f=15 cm. Image is:
Q38.
The angle of deviation at minimum deviation for a prism of apex angle A and refractive index n:
Q39.
A person with far point at 2 m needs glasses. Lens power needed:
Q40.
For a converging mirror, if object moves from infinity toward focus, image moves from:
Q41.
Resolving power of a microscope increases when:
Q42.
A convex mirror has focal length 15 cm. Object at 30 cm. Image position:
Q43.
In a glass prism, dispersion occurs because:
Q44.
An astronomical telescope has objective focal length 150 cm and eyepiece focal length 5 cm. Magnification:
Q45.
For presbyopia, the patient needs:
Q46.
If a concave mirror has focal length 20 cm and object is at 15 cm (inside focus). Image is:
Q47.
Critical angle in a medium is 45 degrees. Refractive index is:
Q48.
For human eye, near point is approximately at:
Q49.
Total deviation produced by two mirrors at angle theta between them when light undergoes two reflections:
Q50.
A convex lens of glass (n = 1.5) has focal length 20 cm in air. When fully immersed in water (n = 1.33), its focal length becomes about:
Q51.
An equiconvex lens is made of glass (n = 1.5) with each surface of radius of curvature 20 cm. Its focal length is:
Q52.
An optical fibre has a core of refractive index 1.60 and cladding of refractive index 1.50. The critical angle at the core-cladding interface is about:
Q53.
Two thin convex lenses of focal lengths 10 cm and 20 cm are placed coaxially 5 cm apart. The focal length of the combination is:
Q54.
For a glass, n<sub>violet</sub> = 1.53, n<sub>red</sub> = 1.51 and n<sub>yellow</sub> = 1.52. The dispersive power of the glass is about:
Q55.
By the displacement method, an object and screen are fixed 100 cm apart. A convex lens forms a sharp image for two lens positions 40 cm apart. The focal length of the lens is:
Q56.
A concave mirror has radius 40 cm. Object at 60 cm. Find image (distance, nature, magnification):
Q57.
Light from a source travels through glass (n=1.5) and hits a glass-water (n=1.33) interface. Critical angle:
Q58.
A compound microscope has fo=1 cm, fe=5 cm, tube length 20 cm. Magnification (image at 25 cm from eye):
Q59.
A plano-convex lens of glass (n=1.5) has curved surface R=20 cm. Placed with flat surface in water (n=1.33). Focal length:
Q60.
For a thin prism of small angle A, deviation = (n-1)A. For two thin prisms of same glass material but different apex angles in contact with reversed orientation producing zero deviation. For white light dispersion:
Q61.
In an achromatic doublet, two lenses of different materials are combined to eliminate chromatic aberration. Condition:
Q62.
A fish in water (n=1.33) looking up at angle 90 degrees sees refracted image at what angle (apparent cone angle):
Q63.
A concave mirror with f=20 cm. At what distance should an object be placed so image is 3 times the object size and real?
Q64.
Apparent depth of an object at real depth d in a medium of refractive index n:
Q65.
A person sees a fish that appears 12 cm deep in water (n=1.33). Actual depth of fish:
Q66.
For an equilateral prism (A=60 deg, n=sqrt(3)) in minimum deviation condition, angle of incidence:
Q67.
A lens forms image I of object O. If lens is cut along principal axis (top half removed), which happens?
Q68.
Two plane mirrors inclined at 72 degrees. Number of images formed:
Q69.
A convex mirror has focal length 20 cm. Object is 20 cm in front. Magnification:
Q70.
A glass slab of thickness t and refractive index n is placed in path of light. Normal shift in image position:
Q71.
Critical angle for medium A (n=1.5) to medium B (n=1.2):
Q72.
A camera uses a converging lens. The image of a distant object forms at:
Q73.
Which aberration causes different colors to focus at different points?
Q74.
Eye lens has focal length 25 mm at far point and 22 mm at near point. Power variation:
Q75.
A ray enters the flat face of a semicircular glass (n=1.5) at the center. Minimum angle of incidence for TIR at curved surface:
Q76.
An object is placed at the centre of curvature (2f) of a concave mirror. The image formed is:
Q77.
An object is placed 30 cm in front of a convex lens of focal length 20 cm. The image distance is:
Q78.
For a medium of refractive index 1.5, the critical angle for total internal reflection is about:
Q79.
The power of a lens of focal length 25 cm is:
Q80.
Two thin lenses of powers +10 D and −4 D are placed in contact. The net power of the combination is:
Q81.
A prism of angle 60° and refractive index 1.5 is at minimum deviation. The angle of minimum deviation is about:
Q82.
The defect of vision called myopia (short-sightedness) is corrected using a:
Q83.
For the object at 30 cm and convex lens of focal length 20 cm (image at 60 cm), the magnification is:
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