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

Which of the following materials has maximum optical density?
  • Glass
  • Water
  • Pearl
  • Diamond
The magnification of plane mirror is always ...............
  • More than 1
  • 1
  • Less than 1
  • Zero
Which of the following formula is wrong in accordance with Snell's law ?
  • $$ \dfrac{n_1}{\sin i} = \dfrac{n_2}{\sin r} $$
  • $$ \dfrac{n_{2}}{n_1} = \dfrac{\sin i}{\sin r} $$
  • $$n_{1} \sin i = n_{2} \sin r$$
  • $$\dfrac{1}{n_2} \sin i = \dfrac{1}{n_1} \sin r $$
A concave mirror forms the real image of an object which is magnified 4 times. The object is moved 3 cm away, the magnification of the image is 3 times. What is the focal length of the mirror?
  • 3 cm
  • 4 cm
  • 12 cm
  • 36 cm
A convex mirror has a focal length of 20 cm. A real object is placed at a distance of 20 cm from the pole of the mirror and in front of the mirror. The mirror produces an image at :
  • Infinity
  • 20 cm
  • 40 cm
  • 10 cm
A rod of length 10 cm lies along the principal axis of concave mirror of focal length 10 cm in such a way thatits end closer to the pole is 20 cm away from the mirror. The length of the image is then -
  • 15 cm
  • 2.5 cm
  • 5 cm
  • 10 cm
Refractive indices of water and glass are 4/3 and 3/2 respectively. A ray of light travelling in water is incident on the water-glass interface at $$30^0$$. Calculate the sine of angle of refraction.
  • 0.460
  • 0.585
  • 0.444
  • 0.623
You are given water, mustard oil, glycerine, and kerosene. In which of these media a ray of light is incident obliquely at same angle would bend the most ?
  • Kerosene
  • Water
  • Mustard oil
  • Glycerine
A pin that is 2 cm long is placed at a distance of 16 cm from a convex lens. Assuming it to be perpendicular to the principal axis, find the position of the image if the focal length of the lens is 12 cm.
  • 48 cm
  • 24 cm
  • 12 cm
  • None of these
What is the focal length of the convex lens ?
  • 20 cm
  • 40 cm
  • 19 cm
  • 12 cm
The magnitude of focal length of a concave mirror is $$f$$. An object is placed at a distance $$x$$ from the focus and forms a real image. The magnification is:
  • $$-\dfrac{f}{x}$$
  • $$-\dfrac{x}{f}$$
  • $$-\dfrac{f}{f-x}$$
  • $$\dfrac{x}{x-f}$$
Sunlight takes $$8 \ min \ 20 \ s$$ to reach the earth. If the entire space in between is filled with water, the light will take: 
$$\left( _{a}\mu_{w}=\dfrac{4}{3} \right)$$
  • 6 min
  • 11 min 6 s
  • 8 min 10 s
  • 8 min
A real object is placed at a distance $$\dfrac{f}{2}$$ in front of a concave mirror having focal length $$f$$. If object is shifted by a distance $$\dfrac{f}{4}$$ away from the mirror. Find the ratio of final magnification to initial magnification.
  • $$4$$
  • $$\dfrac{1}{4}$$
  • $$\dfrac{1}{2}$$
  • $$2$$
An object is placed on the principal axis of a concave mirror at a distance of 60 cm. If the focal length of the concave mirror is 40 cm then determine the magnification of the obtained image.
  • 2
  • -2
  • 2.5
  • -2.5
In a vessel, as shown in fig, point P is just visible when no liquid is filled in vessel through a telescope in the air. When liquid is filled in the vessel completely, point Q is visible without moving the vessel or telescope. Find the refractive index of the liquid.

159945_a340e319ac844757bf95e33e3a4cb18a.png
  • $$\dfrac {\sqrt {14}}{3}$$
  • $$\dfrac {\sqrt {85}}{5}$$
  • $$\sqrt 2$$
  • $$\sqrt 3$$
The focal length of a concave mirror is f and the distance from the object to the principal focus is p. The ratio of the size of the real image to the size of the object is:
  • $$-\displaystyle \frac{f}{p}$$
  • $$\displaystyle \left(\frac{f}{p}\right)^2$$
  • $$\displaystyle \left(\frac{f}{p}\right)^{\frac{1}{2}}$$
  • $$-\displaystyle \frac{p}{f}$$
  • $$-fp$$

160912.png
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
When light falls on a given plate at angle of incidence of $$60^o$$, the reflected and refracted rays are found to be normal to each other. The refractive index of the material of the plate is then
  • 0.866
  • 1.5
  • 1.732
  • 2
When a light ray moves from air to a transparent medium the angle of incidence and the angle of refraction are $$45^{\circ}$$ and $$30^{\circ}$$ respectively. Find the refractive index of this medium is
  • $$1.21$$
  • $$1.42$$
  • $$1.88$$
  • $$2.42$$
The image of an object placed on the principal axis of a concave mirror of focal length $$12\ cm$$ is formed at a point which is $$10\ cm$$ more distant from the mirror than the object. The magnification of the image is
  • $$8/3$$
  • $$2.5$$
  • $$2$$
  • $$-1.5$$
The refractive indices of substances P,Q, Rand S are 1.38, 1.46, 1.56 and 1.24 respectively. When light travelling in air is incident on these substances at equal angles, the angle of refraction will be maximum in
  • P
  • Q
  • R
  • S
A ray of light is incident from one medium $$(\mu = 1.5)$$ into another medium. If the angle of incidence and refraction are, respectively, $$60$$ and $$45$$, then what will be the refractive index of the denser medium?
  • $$1.63$$
  • $$1.43$$
  • $$1.83$$
  • Data insufficient
Which of the following correctly represents the graphical variation between very small angles of incidence (i) and refraction (r) ?
In the figure below, PQRS denotes the path followed by a ray of light as it travels three media in succession. The absolute refractive indices of the media are $$\mu_1 \, \mu_2\, and\, \mu_3 $$ respectively. (The line segment RS' in the figure is parallel to PQ). Then :
333196_eb56473b8ee545cdbc6cac3a342feed2.png
  • $$\mu_1\, > \, \mu_2\, >\, \mu_3$$
  • $$\mu_1\, < \, \mu_3\, \mu_2$$
  • $$\mu_1\, = \, \mu_3\, <\, \mu_2$$
  • $$\mu_1\, < \, \mu_3\, <\, \mu_2$$
An object is placed at a distance of 20 cm from a convex mirror or radius of curvature 40 cm. At what distance from the object should a plane mirror be placed so that the images due to the mirror and the plane mirror are in the same plane?
  • 15 cm
  • 30 cm
  • 60 cm
  • 40 cm
What is a magnifying glass used for?
  • Read large prints
  • Read small prints
  • To diverge rays
  • As a diverging lens
An object is placed on the principal axis of a concave mirror at a distance of $$60\ cm$$. If the focal length of the concave mirror is $$40\ cm$$ then determine the magnification of the obtained image.
  • $$4$$
  • $$-2$$
  • $$-4$$
  • $$+2$$
Which of the following is a spherical lens?
  • Concave lens
  • Convex lens
  • Diverging lens
  • All
A glass slab has two long parallel faces. Light ray is incident on the glass slab and trace of light ray is drawn. Now glass slab is shifted parallel to the parallel faces. What will be the effect on the trace of light?
  • It will shift laterally
  • Angle of deviation will change
  • No effect
  • Depends on amount of shift
A ray of light is incident on the interface between water and glass at an angle i and refracted parallel to the water surface, then value of $$\mu_g$$, refractive index of glass will be:

473692_c3b736e375c5499daeb2373faab86678.png
  • $$(4/3)\sin i$$
  • $$\displaystyle\frac{1}{\sin i}$$
  • $$\displaystyle\frac{4}{3}$$
  • $$1$$
A spherical lens has a focal length $$2\ cm$$. The lens will be
  • Concave lens
  • Convex lens
  • Concavo convex lens
  • None
The diameter of the reflecting surface of spherical mirror is called ..............
  • Focus
  • Aperture
  • Centre of curvature
  • None of these
Magnification of lens is:
  • $$\dfrac {\text {Size of the image}}{\text {Size of the object}}$$
  • $$\dfrac {\text {Image distance}}{\text {Object distance}}$$
  • Both A and B
  • None
The radius of the sphere of which the reflecting surface of a spherical mirror forms a part, is called ...............
  • Centre of curvature
  • Radius of curvature
  • Focus
  • Pole
Curved mirror whose reflecting surface faces towards the centre of the sphere, from which is considered to be a part of, is known as
  • Convex mirror
  • Concave mirror
  • Plane mirror
  • None
A water film is formed on a glass-block. A light ray is incident on water film from air at an angle of $$\displaystyle { 60 }^{ \circ  }$$ with the normal. The angle of incidence on glass slab is
($$\displaystyle { \mu  }_{ g } = 1.5,{ \mu  }_{ w } = \frac { 4 }{ 3 } $$)
  • $$\displaystyle { sin }^{ -1 }\left( \frac { 3\sqrt { 3 } }{ 8 } \right) $$
  • $$\displaystyle { sin }^{ -1 }\left( \frac { 1 }{ \sqrt { 3 } } \right) $$
  • $$\displaystyle { sin }^{ -1 }\left( \frac { 4\sqrt { 3 } }{ 9 } \right) $$
  • $$\displaystyle { sin }^{ -1 }\left( \frac { 9\sqrt { 3 } }{ 16 } \right) $$
As shown in above figure, a beam of light in air is incident upon the smooth surface of glass $$30^o$$ with glass surface. Calculate the refractive index of the glass if the reflected beam and refracted beam are perpendicular to each other.

480876_f22c6ee9909a4de28bc3a654c46a2e17.png
  • $$\frac{1}{2}$$
  • $$\frac{1}{2}\sqrt{3}$$
  • $$\sqrt{3}$$
  • $$2\sqrt{3}$$
  • $$3\sqrt{3}$$
An object is placed at 20 cm in front of a concave mirror produces three times magnified real image. What is focal length of the concave mirror?
  • 15 cm
  • 6.6 cm
  • 10 cm
  • 7.5 cm
Which lens is used in a magnifying glass?
  • Concave
  • Convex
  • Diverging
  • Converging
A beam of light striking the surface of a glass plate from the air as shown in above figure.
If the angle between reflected beam and refracted beam is 90 degree, Find out the refractive index of the glass?
480610.jpg
  • $$\sin{{55}^{o}}$$
  • $$\dfrac{1}{\sin{{55}^{o}}}$$
  • $$\dfrac{1}{\sin{{35}^{o}}}$$
  • $$\dfrac{\sin{{55}^{o}}}{\sin{{35}^{o}}}$$
  • $$\dfrac{\sin{{35}^{o}}}{\sin{{55}^{o}}}$$
In above shown figure, an object is kept 20 cm from the concave mirror and formed the real image at the distance of 5 cm from the mirror. Calculate the focal length of the mirror.
481939_f58cd8a474da4e3388e6859401e55a12.png
  • 2.5 cm
  • 4 cm
  • 25 cm
  • 20 cm
  • 40 cm
Below is a drawing made by a student that represents a light ray entering a piece of plastic and passing into the plastic. The student drew the original light ray to enter the plastic at a $$60.0$$ degree angle with the normal as pictured.
He was able to look through the plastic and line up a ruler with the original light ray he drew to measure the angle of the light ray in the plastic. This angle is labeled in the drawing. The student used his drawing to determine the index of refraction for the plastic.
What value did he determine?
499203.jpg
  • $$1.66$$
  • $$0.602$$
  • $$1.47$$
  • $$0.68$$
  • $$1.38$$
A ray of light traveling in the air is incident on the plane of a transparent medium. The angle of the incident is 45$$^o$$ and that of refraction is 30$$^o$$. Find the refractive index of the medium.
  • 2
  • $$\dfrac{1}{\sqrt 2}$$
  • $$2 \sqrt 2$$
  • $$\sqrt 2$$
Which of the following is Snell's law
  • $$n_1 sini = n_2 sinr$$
  • $$n_{1}/n_{2} = \sin r \times constant$$
  • $$n_{2}/n_{1} = \sin r/ \sin i$$
  • $$n_{2} \sin i = constant$$
A concave mirror of focal length 'f' produces an image 'n' times the size of the object. If the image is real then the d distance of the object from the mirror is
  • $$(n + 1 )f$$
  • $$\dfrac{(n+1) f}{n}$$
  • $$\dfrac{(n-1) f}{n}$$
  • $$(n-1)f$$
A light is travelling from air into a medium. Velocity of light in a medium is reduced to $$0.75$$ times the velocity in air. Assume that angle of incidence '$$i$$' is very small, the deviation of the ray is
  • $$i$$
  • $$\dfrac { i }{ 3 } $$
  • $$\dfrac { i }{ 4 } $$
  • $$\dfrac { 3i }{ 4 } $$
Study the given ray diagrams and select the correct statement from the following:
624567_d3c7d74633904ed489635046e465118a.30-Resize
  • Device X is a concave mirror and device Y is a convex lens, whose focal lengths are 20cm and 25cm respectively.
  • Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 20cm and 25cm respectively.
  • Device X is a concave lens and device Y is a convex mirror, whose focal lengths are 20cm and 25cm respectively.
  • Device X is a concave lens and device Y is a concave mirror, whose focal lengths are 20cm and 25cm respectively.
A convex mirror of focal length $$f$$ forms an image which is $$\cfrac { 1 }{ n } $$ times the object. The distance of the object from the mirror is :
  • $$\left( \cfrac { n-1 }{ n } \right) f$$
  • $$\left( \cfrac { n+1 }{ n } \right) f$$
  • $$(n+1)f$$
  • $$(n-1)f$$
A diverging lens forms _______ & ________ image
  • Erect
  • Real
  • Virtual
  • Magnified
Gita arranges some mirrors in group- $$1$$ and group- $$2$$ according to the magnification, type of image and size of image from the following data.
Sr. No.Group-$$1$$Group-$$2$$
$$(1)$$$$<1$$ and negativeReal, inverted and small
$$(2)$$$$>1$$ and positiveReal, inverted and enlarged
$$(3)$$$$>1$$ and negativeVirtual, erect and enlarged
$$(4)$$$$<1$$ and positiveVirtual, erect and small
For which of the pairs from the group $$1$$ and $$2$$ you disagree.
  • $$1$$ and $$3$$
  • $$2$$ and $$3$$
  • $$3$$ and $$4$$
  • $$1$$ and $$2$$
0:0:1


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