CBSE Questions for Class 10 Physics Light Reflection And Refraction Quiz 4 - MCQExams.com

During refraction through a glass block, the angle of refraction _______.
  • increases
  • decreases
  • remains same
  • cant say
The refractive index of glass is $$1.5$$. From a point $$P$$ inside a glass block, draw rays $$PA, PB$$ and $$PC$$ incident on the glass-air surface at an angle of incidence $$30^o, 42^o$$ and $$60^o$$ respectively. What is the angle of refraction for the ray $$PB$$ ?  (Take $$\sin 42^o = \cfrac{2}{3}$$ )
  • $$0^o$$
  • $$30^o$$
  • $$60^o$$
  • $$90^o$$
The centre of curvature of a concave mirror :
  • lies in front of it
  • lies behind it
  • lies on the surface of mirror
  • none of these
A fish is looking at a $$1.0m$$ high plant of the edge of the pond. Will the plant appear shorter or taller than its actual height, to the fish 
  • taller
  • shorter
  • no change
  • can't say
A ray of light passing through the .......... of the lens, passes on undeviated.
  • principal focus
  • pole
  •  optical centre
  •  principal axis
For an object placed at a distance $$20 \ cm$$ in front of a convex lens, the image is at a distance $$20 \ cm$$ behind the lens. The focal length of convex lens is:
  • $$20 \ cm$$
  • $$10  \ cm$$
  • $$15 \ cm$$
  • $$40 \ cm$$
A ray of light is incident on a lens parallel to its principal axis. After refraction, the ray passes through or appear to come from :
  • its first focus
  • its optical centre
  • its second focus
  • the centre of curvature of its second surface
What is the distance $$PB$$ called?
202643_dcd006c2b7f242debe7af7af7f57413e.png
  • Efficient length
  • Radius of curvature
  • Equivalent length
  • Focal length.
A ray of light travelling inside a rectangular glass block of refractive index $$\sqrt2$$ is incident on the glass-air surface at an angle o incidence of $$45^o$$.The refractive index of air is one. Under these conditions the ray will
  • emerge into the air without any deviation
  • be reflectived back into the glass
  • be absorbed
  • emerge into the air with an angle of refraction equal to $$90_o$$
According to the new Cartesian sign convention, the _______ of a curved mirror is taken at origin.
  • Centre of curvature
  • Pole of the mirror
  • Focus
  • Midpoint of focus and pole
An object of length $$4 \ cm$$ is placed in front of a concave mirror at a distance of $$30 \ cm$$. The focal length of mirror is $$15\ cm$$. What will be the length of image?
  • $$1 \ cm$$
  • $$2 \ cm$$
  • $$4 \ cm$$
  • $$6 \ cm$$
A concave lens has focal length of $$15 \ cm$$. At what distance should the object from the lens be placed so that it forms an erect and virtual image at $$10 \ cm$$ from the lens?
  • $$\displaystyle 30$$ $$cm$$
  • $$\displaystyle 15$$ $$cm$$
  • $$\displaystyle 60$$ $$cm$$
  • $$\displaystyle 10$$ $$cm$$
The path of a ray of light coming from air passing through a rectangular slab traced by four students are shown by figures A, B, C and D. Which one of them is correct?
A point source of light is placed in front of a plane mirror, then :
  • all the reflected rays will meet at a point when produced backward
  • only the reflected rays close to the normal will meet at a point when produced backward
  • only the reflected rays making a small angle with the mirror will meet at a point when produced backward
  • light of different colours will make different images
Which of the following (referred to as spherical mirror) depends on whether the rays are paraxial or not?
  • Pole
  • Focus
  • Radius of curvature
  • Principal axis
An incident ray passing through the focus will be reflected :
  • straight away
  • through the pole of the mirror
  • back and passes through the centre of curvature
  • parallel to the principal axis
A real image :
  • cannot be captured on a screen
  • can be captured on a screen
  • can be captured only on a celluloid screen
  • none of the above
Focus is real in the case of
  • Concave mirror
  • Convex mirror
  • Plane mirror
  • None of the above
In a spherical mirror, normal drawn on any point on a spherical mirror passes through :
  • Focus
  • Pole of the mirror
  • Centre of curvature
  • None of the above
An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. The image produced is:
  • real, inverted and smaller in size
  • real, inverted, and of same size
  • real and erect
  • virtual and inverted
A printed page is seen through a glass slab placed on it. The printed words appear raised. This is due to :
  • refraction at the upper surface of the slab
  • refraction at the lower surface of the slab
  • partial refraction at the upper surface of the slab
  • partial refraction at the lower surface of the slab
In the glass slab experiment,the correct placement of the protractor (or 'dec'),for measuring the angles of incidence and emergence,is shown in which figure?
After tracing the path of a ray of light passing through a rectangular glass slab for four different values of the angle of incidence, a student reported his observations in tabular form as given below :

S.No		 <i<r< e

I		$${30^0}$$$${19^0}$$$${29^0}$$
II$${40^0}$$$${28^0}$$$${40^0}$$
III$${50^0}$$$${36^0}$$$${50^0}$$
IV$${60^0}$$$${40^0}$$$${59^0}$$
The best observation is :
  • I
  • II
  • III
  • IV
Focus is virtual in the case of
  • Concave mirror
  • Convex mirror
  • Plane mirror
  • None of the above
The second law of refraction states that :
  • $$\dfrac{\sin^2 i}{\sin^2 r}=\mu$$
  • $$\dfrac{\sin i}{\sin r}=\mu$$
  • $$\sqrt{\dfrac{\sin i}{\sin r}}=\mu$$
  • none of these are true
A convex lens is a convergent lens and is used as a magnifying glass
  • True
  • False
When the distance between the object and the plane mirror increases:
  • the image distance remains same
  • the size of the image will become less than the size of the object
  • the distance between the image and the plane mirror increases
  • the distance between the image and the plane mirror decreases
The center of the lens is called :
  • Principle focus
  • Principle axis
  • Optical centre
  • None
If the refractive index of medium $$b$$ with respect to medium $$a$$ and that of medium $$c$$ with respect to medium $$b$$ are given as $$n_{ba}$$ and $$n_{cb}$$ respectively, then the refractive index of a medium $$c$$ with respect to a medium $$a$$ can be found by using the relation
$$n_{ca}\, =\, n_{ba}\, \times\, ........$$
  • $$n_{cb}$$
  • $$n_{ac}$$
  • $$n_{ca}$$
  • $$n_{ba}$$
State whether the following statement is True or False. 
A concave lens is a divergent lens and is used in projectors
  • True
  • False
The first law of refraction states that the incident and refracted rays are in the same ________ as the normal.
  • phase
  • plane
  • both
  • none
The second law of refraction is also named after its discoverer as :
  • Newton's law
  • Faraday's law
  • Snell's law
  • Charles' law
The second law of reflection states that the incident ray, the refracted ray, and the normal at the point of incidence, all lie in the ................ plane.
  • parallel
  • same
  • perpendicular
  • different
As shown in the figure, the point $$C$$ is called the

283651_5b4d0ff82a234c4bb78a6b7901a87add.png
  • optical center of the lens.
  • principal axis of the lens.
  • focus of the lens.
  • power of the lens.

What is the shape of lens C as shown in figure ?
284382_a98fe02c9e7c4de3b25e8423de3e24f6.png
  • Plano-convex
  • Plan-concave 
  • Convex 
  • Concave 
.......... happens when a wave passes from one medium to another at an angle.
  • Refraction
  • Reflection
  • Dispersion
  • Scattering
A coin kept in a container and not visible can be viewed by pouring water into the container. It happens because of the 
  • Reflection of light.
  • Refraction of light.
  • Variable refractive index of water.
  • None of the above.
Select the correct alternative
The angle between the normal and refracted ray is called :
  • angle of deviation
  • angle of incidence
  • angle of refraction
  • none of these
The focal length is the distance from the optical center of the lens to its principal _________
  • focus.
  • axis.
  • center of curvature.
  • lens.
Fill in the blank. 
A _____ is a piece of transparent glass bounded by two spherical surfaces. 
  • lens
  • mirror
  • both  
  • none 
A student uses a converging lens to produce an enlarged virtual image of a scale she wishes to read accurately. The focal length of the lens is $$10\;cm$$. What is a suitable distance between the scale and the lens ?
  • $$8\;cm$$
  • $$10\;cm$$
  • $$15\;cm$$
  • $$20\;cm$$
Snell's law is law of reflection.
  • True
  • False
The linear magnification for a mirror is the ratio of the size of the image to the size of the object, and is denoted by $$'m'$$. Then $$m$$ is equal to $$\left(\dfrac{-f}{u - f}\right)$$ (symbols have their usual meanings)
  • True
  • False
A ray of light enters a slab of material with increasing refractive index. Four possibilities of the trajectory of the ray are shown below.
The correct choice is:
330672.jpg
  • A
  • B
  • C
  • D

From the shown figure, name the lens which is plano-concave :
284385_e8c2a96e67854e2083aed228bee39f7d.png
  • D
  • A
  • B
  • C
An under-water swimmer cannot see very clearly even in absolutely clear water because of:
  • Absorption of light in water
  • Scattering of light in water
  • Reduction of speed of light in water
  • Change in the focal length of eye lens.
A convex mirror of focal length $$f$$ (in air) is immersed in a liquid $$\displaystyle \left( \mu =\frac { 4 }{ 3 }  \right) $$. The focal length of the mirror in liquid will be:
  • $$\displaystyle \left( \frac { 3 }{ 4 } \right) f$$
  • $$\displaystyle \left( \frac { 4 }{ 3 } \right) f$$
  • $$\displaystyle f$$
  • $$\displaystyle \left( \frac { 7 }{ 3 } \right) f$$
The linear magnification for a mirror is the ratio of the size of the image to the size of the object, and is denoted by $$m$$. Then we may write: (symbols have their usual meanings)
  • $$f=\dfrac{1+m}{mu}$$
  • $$f=mu$$
  • $$f=\dfrac{mu}{1+m}$$
  • None of these
A convex lens of focal length10 cm is placed at a distance of 12 cm from a wall. How far from the lens should an object be placed so as to form its real image on the wall?
  • 30 cm
  • 15 cm
  • 120 cm
  • 60 cm
Which of the following does not represent correct refraction?
0:0:1


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