CBSE Questions for Class 10 Physics Light Reflection And Refraction Quiz 9 - MCQExams.com

A ray of light strikes a glass slab $$(R.l=\mu)$$ of finite thickness $$t$$. The emerging light is 
  • parallel to the incident ray
  • perpendicular to the incident ray
  • rotates by an angle $$\left[t \sin^{-1}\left( \dfrac {1}{\mu}\right)\right]$$
  • totally internally reflected
An object is placed at a distance of $$5$$ cm from a convex lens of focal length $$10$$ cm, then the image 
  • -10
  • -20
  • -30
  • -40
Four students perform an experiment on tracing the path of a ray of light passing through a rectangular glass slab. Their individual observations are:
identify the incorrect observation and correct them.
  • angle of emergence is less than the angle of refraction
  • angle of emergence is greater than the angle of incidence
  • emergent ray is parallel to the refracted ray
  • emergent ray is parallel to the incident ray
An object is placed at a distance of $$25cm$$ on the axis of a concave mirror, having focal length $$20cm$$. Find the lateral magnification of an image
  • $$-4$$
  • $$-2$$
  • $$4$$
  • $$2$$
An object is at $$0.06$$ m from a convex lens of focal length $$0.10$$m. Find the position of the image.
  • $$15 m$$
  • $$50 m$$
  • $$15 cm$$
  • $$50 cm$$
Time taken by the sunlight to pass through a window of thickness 4mm whose refractive index is 1.5 is 
  • $$3 \times 10^{-8}s$$
  • $$2 \times 10^{-8}s$$
  • $$3 \times 10^{-11}s$$
  • $$2 \times 10^{-11}s$$
An illuminated object lies at a distance 1.0 m from a screen. A convex lens is used to form the image of object on a screen placed at distance 75 cm from the lens. Find : (i) the focal length of lens, and (ii) the magnification.
  •  (i) 15.75 cm (ii) -2
  • (i) 18.75 cm (ii) -3
  •  (i) 19.75 cm (ii) 2
  •  (i) 17.75 cm (ii) -3
A convex lens
  • Diverges light rays
  • Converges light rays
  • Form real images always
  • Always forms virtual images
A candle placed $$25 \,cm$$ form a lens forms an image on a screen placed $$75 \,cm$$ on the other side of the lens. The focal length and type of the lens should be
  • $$+18.75 \,cm$$ and convex lens
  • $$-18.75 \,cm$$ and concave lens
  • $$+20.25 \,cm$$ and convex lens
  • $$-20.25 \,cm$$ and concave lens
A man with normal near point $$(25 \,cm)$$ reads a book with small point using a magnifying glass, a thin convex lens of focal length $$5 \,cm$$.
  • the closest distance at which he can read the book when viewing through the magnifying glass is $$4.17 \,cm$$
  • the farthest distance at which he can read the books when viewing through the magnifying glass is $$5 \,cm$$
  • the maximum and minimum magnifying power possible using the above simple microscope are 5 & 6.
  • All the above
What should be the distance between an object and a concave mirror of focal length of 20 cm so that a virtual image is produced at the distance of 10 cm form the mirror ?
  • 12 cm
  • 6.6 cm
  • 30 cm
  • 25 cm
An arrow is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the image distance.
  • $$12.1 cm$$
  • $$13.1 cm$$
  • $$11.1 cm$$
  • $$14.2 cm$$

A convex lens produces an image of an object on a screen with a magnification of $$\frac{1}{2}$$ .When the lens is moved 30 cm away from the object, the magnification of the image is 2.The focal length of the lens is
  • 20 cm
  • 25 cm
  • 30 cm
  • 35 cm
If the angle of incidence and angle of emergence of a light ray falling on a glass slab are i and e respectively    then i=e
  • True
  • False
A fish looking up through the water sees the outyside world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12 cm below the surface, the radius of this circle in cm is 
  • $$36\sqrt{7}$$
  • $$36/\sqrt{7}$$
  • $$36/\sqrt{5}$$
  • $$4/\sqrt{5}$$
Return of light after striking a surface is called the refraction of light.
  • True
  • False
The refractive indices of water and glass are $$\frac{4}{3}\,and\,\frac{3}{2}$$ respectively. The refractive index of water respect to glass is ;
  • $$\frac{8}{9}$$
  • $$2$$
  • $$\frac{2}{3}$$
  • $$\frac{1}{6}$$
A ray of light is incident normally on one of the faces of a prism of apex angle $$30^o$$ and refractive index $$\sqrt 2$$. The angle of deviation of the ray is
  • $$30^o$$
  • $$60^o$$
  • $$15^o$$
  • $$90^o$$
Refractive index of glass is $$\dfrac {3}{2}$$ and refractive index of water is $$\dfrac {4}{3}$$. If the speed of light in glass is $$2.00\times 10^8\ m/s$$ , the speed in water will be
  • $$2.67\times 10^8 m/s$$
  • $$2.25\times 10^8 m/s$$
  • $$1.78\times 10^8 m/s$$
  • $$1.50\times 10^8 m/s$$
A ray is inclident on boundary separating glass and  water Refractive index for glass is $$\frac{3}{2}$$ and refractive index for water is $$\frac{4}{3}$$ critical angle for glass-air boundary is
  • $$sin^{-1}$$$$(\frac{3}{4})$$
  • $$sin^{-1}$$$$(\frac{2}{3})$$
  • $$sin^{-1}$$$$(\frac{8}{9})$$
  • $$sin^{-1}$$$$(\frac{1}{9})$$
A convex lens of focal length $$10\ cm$$ forms a vitual image of an object at $$30\ cm$$ from the lens. The magnification produced will be:
  • $$2$$
  • $$3$$
  • $$3.5$$
  • $$4$$
Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence? 
  • $$n > \surd 2$$
  • $$n = 1$$
  • $$n = 1.1$$
  • $$n = 1.3$$
An object is placed first at infinity and then at $$20\ cm$$ from the object side focal plane of the convex lens. The two images thus formed are $$5\ cm$$ apart. The focal length of the lens is:
  • $$5\ cm$$
  • $$10\ cm$$
  • $$15\ cm$$
  • $$20\ cm$$
Light of frequency $$5\times 10^{14}\ Hz$$ is travelling in a medium of refractive index $$1.5$$. What is its wavelength ? $$(c=3\times 10^{8}\ ms^{-1})$$
  • $$9000\ \mathring { A } $$
  • $$6000\ \mathring { A } $$
  • $$4500\ \mathring { A } $$
  • $$4000\ \mathring { A } $$
When a glass rod is immersed in a liquid of same refractive index, it will _____.
  • Appear bent
  • Disappear
  • Appear longer
  • Not be affected
When a beam of light goes from a denser medium $$ \left(\mu_{d}\right)  $$ to a rarer medium ( $$  \mu_{r} ),  $$ then it is generally observed that magnitude of angle of incidence is half that of angle of refraction. Then magnitude of incident angle will be - (here $$  \mu=\mu_{d} / \mu_{r} )  $$
  • 2$$ \sin ^{-1}\left(\frac{\mu}{2}\right) $$
  • 2$$ \cos ^{-1} \mu $$
  • $$ \cos ^{-1}\left(\frac{\mu}{2}\right) $$
  • 2$$ \cos ^{-1}\left(\frac{\mu}{2}\right) $$
The geometrical centre of a spherical mirror is called its pole.
  • True
  • False
Calculate the refractive index of glass with respect to water. It is given that refractive indices of glass and water with respect to air are $$\dfrac {3}{2}$$ and $$\dfrac {4}{3}$$ respectively.
  • $$\dfrac {8}{9}$$
  • $$\dfrac {9}{8}$$
  • $$\dfrac {7}{6}$$
  • $$none\ of\ these$$
At what distance a person should face a concave mirror of focal length $$0.4 \ m$$ so that magnification is 5 times for a virtual image
  • $$32 \ cm$$
  • $$24 \ cm$$
  • $$16 \ cm$$
  • $$50 \ cm$$
A ray of light is incident on the surface of transparent medium at an angle of $$45^o$$ and is refracted in the medium at an angle of $$30^o$$. What will be the velocity of light in the transparent medium ? 
  • $$1.96 \times 10^8 m/s $$
  • $$2.12 \times 10^8 m/s$$
  • $$2.65 \times 10^8 m/s $$
  • $$1.25 \times 10^8 m/s $$
Select the correct alternative (s) :
  • A convex lens may form a real image
  • $$R=2f$$ formula is applicable to only paraxial ray
  • A convex lens becomes less convergent when it is immersed in water
  • All of the above
A Point source of Light is placed $$4 \ m$$ below the surface of water of refractive index $$\dfrac{5}{3}$$. the minimum diameter of a disc which should be placed over the source on the surface of water to cut-off all light coming out of water is: (μ=5/3) 
  • $$2 \ m $$
  • $$ 6 \ m$$
  • $$4\ m$$
  • $$3\ m$$
An object is placed at a distance of $$20$$cm from the pole of a concave mirror of focal length $$10$$cm. The distance of the image formed is?
  • $$+20$$ cm
  • $$+10$$ cm
  • $$-20$$ cm
  • $$-10$$ cm
A candle placed $$25$$cm from a lens forms an image on a screen placed $$75$$cm on the other side of the lens. The focal length and type of the lens should be?
  • $$+18.75$$cm and convex lens
  • $$-18.75$$cm and concave lens
  • $$+20.25$$cm and convex lens
  • $$-20.25$$cm and concave lens
From the base of a hollow cone of height $$ h $$ with a small angle at the top, a small ring was cut off and placed in front of a parallel beam of light (the figure is exaggerated for clarity). At what distance x will rays of light reflected from it intersect the axis of the cone.
1759927_15f9020a5cfb4ec6abefcb4aeb3c0137.png
  • $$ h $$
  • $$ \dfrac{h}{2} $$
  • $$ \dfrac{h}{\sqrt{2}} $$
  • $$ \sqrt{\dfrac{2}{3}} h $$
The magnification equation is the same irrespective of the convex mirror and concave mirror.
  • True
  • False
You are provided with a convex mirror, a concave mirror, a convex lens and a concave lens. You can get an inverted image from
  • Both concave lens and convex lens.
  • Both concave mirror and convex mirror.
  • Both concave mirror and convex lens.
  • Both convex mirror and concave lens.
Write true or false for each statement 
A concave mirror converges the light-rays , but a convex mirror diverges them. 
  • True
  • False
Select the correct alternative
A ray of light moving from an optically rarer to a denser medium 
  • Bends away from the normal
  • Bends towards the normal
  • Remains undeviated
  • None of the above
When a ray of light from air enters a denser medium, it:
  • bends away from the normal
  • bends towards the normal
  • goes undeviated
  • is reflected back
The refractive indices of glass and water w.r.t air are $$\dfrac{3}{2}$$ and $$\dfrac{4}{3}$$ respectively. The refractive index of glass w.r.t water will be
  • $$\dfrac{8}{9}$$
  • $$\dfrac{9}{8}$$
  • $$\dfrac{7}{6}$$
  • None of these
Absolute refractive indices of glass and water are $$\dfrac {3}{2}$$ and $$\dfrac {4}{3}$$. The ratio of velocity of light in glass and water will be
  • $$4:3$$
  • $$8:7$$
  • $$8:9$$
  • $$3:4$$
The refractive index of water with respect to air is $$4/3$$ and the refractive index of glass with respect to air $$3/2$$. The refractive index of water with respect to glass is
  • $$\dfrac 98$$
  • $$\dfrac 89$$
  • $$\dfrac 12$$
  • $$2$$
If the speed of light in vacuum is $$C\ \ m/sec$$, then the velocity of light in a medium of refractive index $$1.5$$ is
  • $$1.5\times C$$
  • $$C$$
  • $$\dfrac {C}{1.5}$$
  • Can have any velocity
On a glass plate a light wave is incident at an angle of $$60^o$$. If the reflected and the refracted waves are mutually perpendicular, the refractive index of material is
  • $$\dfrac {\sqrt 3}{2}$$
  • $$\sqrt 3$$
  • $$\dfrac {3}{2}$$
  • $$\dfrac {1}{\sqrt 3}$$
When a ray of light passes through the second optical medium with a change in the angle, the phenomenon is known as:
  • Reflection of light
  • Absorption of light
  • Refraction of light
  • None of these
A point object is placed at a distance of $$10\ cm$$ and is real image is formed at a distance of $$20\ cm$$ from a concave mirror. If the object is moved by $$0.1\ cm$$ toward the mirror, the image will shift by about 
  • $$0.4\ cm$$ away from the mirror
  • $$0.4\ cm$$ towards the mirror
  • $$0.8\ cm$$ away from the mirror
  • $$0.8\ cm$$ towards the mirror
Velocity of light in a medium is $$1.5\times 10^8 m/s$$. Its refractive index will be
  • $$8$$
  • $$6$$
  • $$4$$
  • $$2$$
Which of the following event is not related to refraction of light ?
  • The bottom of water filled bowl appears raised.
  • Appearance of sun before sun rising and after sunset
  • Formation of image by mirror
  • Twinkling of stars
Concave lens is known as convergent lens.
  • True
  • False
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