TS 10th Class Physical Science Bits Chapter 4 Refraction of Light at Curved Surfaces

These TS 10th Class Physical Science Bits with Answers Chapter 4 Refraction of Light at Curved Surfaces will help students to enhance their time management skills.

TS 10th Class Physical Science Bits Chapter 4 Refraction of Light at Curved Surfaces

Question 1.
The value of the focal length of the lens is equal to the value of the image distance when the rays are ( )
(A) passing through the optic centre
(B) parallel to the principal axis
(C) passing through the focus
(D) in all the cases
Answer:
(B) parallel to the principal axis

Question 2.
Which of the following is the lens maker’s formula? ( )
(A) 1/f=(n-1) (1/R₁+1/R₂)
(B) 1/f=(n+1) (1/R₁-1/R₂)
(C) 1/f = (n-1) (1/R₁-1/R₂)
(D) 1/f=(n+1) (1/R₁+1/R₂)
Answer:
(C) 1/f = (n-1) (1/R₁-1/R₂)

Question 3.
The height of the image Is hi and the height of the object is ho; then the magnification of the lens, m = ( )
(A) h_i/h₀
(B) h₀/h_i
(C) \(\frac{\mathrm{h}_{\mathrm{o}}+\mathrm{h}_{\mathrm{i}}}{\mathrm{h}_{\mathrm{i}}} \)
(D) \(\frac{\mathrm{h}_{\mathrm{o}}+\mathrm{h}_{\mathrm{i}}}{\mathrm{h}_{\mathrm{o}}} \)
Answer:
(A) h_i/h₀

Question 4.
The distance of the Image formed by a convex lens when the object is kept at a distance of 30 cm. is found to be 10 cm. The focal length of the lens is ( )
(A) 15 cm
(B) 20 cm
(C) 7.5 cm
(D) 12 cm
Answer:
(A) 15 cm

Question 5.
The ability of a lens to converge or diverge light rays depends on Its. ( )
(A) radius of curvature
(B) size
(C) focal length
(D) Intensity of light
Answer:
(C) focal length

Question 6.
A lens having two spherical surfaces bulging outwards is called : ( )
(A) double-concave lens
(B) double convex lens
(C) piano-convex lens
(D) plano-concave lens
Answer:
(B) double convex lens

Question 7.
A lens bounded by two spherical surfaces curved inwards is called: ()
(A) Biconcave lens
(B) Biconvex lens
(C) plano-convex lens
(D) Plano concave lens
Answer:
(A) Biconcave lens

Question 8.
When the object Is at the focal point of a convex lens, the image Is formed at ( )
(A) centre of curvature
(B) at the focal point on the other side of lens
(C) infinity
(D) on the same side of the object
Answer:
(C) infinity

Question 9.
If the object is at 2F of a convex lens, the image Is formed at: ( )
(A) 2F
(B) F
(C) F/2
(D) between F and 2 F
Answer:
(A) 2F

Question 10.
Power of a length is – 2D. Its focal length is ( )
(A) 50cm
(B) 2m
(C) 12cm
(D) 0.5m
Answer:
(D) 0.5m

Question 11.
Point size Image Is formed at focal point of a convex lens when the object is ( )
(A) at 2F₁
(B) between F_T and 2F₁
(C) at infinity
(D) between F₂ and optic centre
Answer:
(C) at infinity

Question 12.
A point source of light Is placed at a distance of 2f from a converging lens of focal length “f”. The Intensity of li9ht Is maximum at a distance ……………………….. on the other side : ( )
(A) at f
(B) between f and 2 f
(C) at 2f
(D) beyond 2f
Answer:
(D) beyond 2f

Question 13.
A helicopter flying vertically above a man in water seems to the man to be its actual distance. ( )
(A) nearer than
(B) farther than
(C) at the same height
(D) none
Answer:
(B) farther than

Question 14.
A thin lens is made of a material having refractive index 1.5; both the sides are bulging outwards. It is dipped in water (n=1.33). It behaves like ( )
(A) convergent lens
(B) a divergent lens
(C) correcting lens
(D) prism
Answer:
(A) convergent lens

Question 15.
For all purposes of application at curved surfaces the distances are measured from ( )
(A) focal point
(B) optic centre
(C) position of image
(D) position of object
Answer:
(B) optic centre

Question 16.
An air bubble in water behaves like a ( )
(A) converging lens
(B) diverging lens
(C) rectifying lens
(D) glass slab
Answer:
(B) diverging lens

Question 17.
The radii of the two spherical surfaces of a double concave lens are 30 cm. and 64 cm. respectively. The refractive index of material of lens = 1.5. The focal length of lens is ( )
(A) 120 cm
(B) -60 cm
(C) -120 cm
(D) 80 cm
Answer:
(C) -120 cm

Question 18.
A convex lens behaves like a ………………… lens when It Is kept in a transparent medium with greater refractive index than that of the lens : ( )
(A) converging
(B) diverging
(C) rectifying
(D) none of these
Answer:
(B) diverging

Question 19.
The focal length of a lens depends upon : ( )
(A) atmospheric temperature
(B) humidity
(C) surrounding medium
(D) air pressure
Answer:
(C) surrounding medium

Question 20.
The nature of the image obtained when object is placed between focus and optic centre of a biconvex lens : ( )
(A) virtual
(B) erect
(C) magnified
(D) all of A, B & C
Answer:
(D) all of A, B & C

Question 21.
We get a real, inverted and magnified image of object when It is placed …………………… of a convex lens : ( )
(A) at centre of curvature
(B) beyond C
(C) between centre of curvature and F
(D) beyond centre of curvature
Answer:
(C) between centre of curvature and F

Question 22.
Any ray passing along the principal axis of a lens ……………………….. . ( )
(A) bends downwards
(B) bends upwards
(C) Is normal to principal axis
(D) travels undefeated
Answer:
(D) travels undefeated

Question 23.
According to sign convention the focal length of a ……………………….. lens is negative ( )
(A) biconvex
(B) concave
(C) cylindrical
(D) none of these
Answer:
(B) concave

Question 24.
The magnification of a lens is found to be (-2). Here the negative sign indicates that the image is ( )
(A) virtual
(B) inverted
(C) real
(D) both B&C
Answer:
(D) both B&C

Question 25.
The reciprocal of the focal length of a lens In metres is called ( )
(A) divergence
(B) shift
(C) power
(D) conductance
Answer:
(C) power

Question 26.
We get a real, inverted diminished image of an object when It is placed of a convex lens : ( )
(A) Beyond 2F₁
(B) At focus F₁
(C) At 2F₁
(D) between F₁ and 2F₁
Answer:
(A) Beyond 2F₁

Question 27.
A lens that always gives a virtual, erect and diminished image is ( )
(A) Bi-convex lens
(B) plano-convex lens
(C) concave lens
(D) all of these
Answer:
(C) concave lens

Question 28.
A transparent material bound by two surfaces, of which one or both are spherical is called : ( )
(A) prism
(B) rectangular glass slab
(C) concave mirror
(D) lens
Answer:
(D) lens

Question 29.
The centres of the spheres of which the surfaces of a lens are parts are called: ( )
(A) focal points
(B) null points
(C) centres of curvatures
(D) in centres
Answer:
(C) centres of curvatures

Question 30.
Lenses form mages by the phenomenon of ………………………. of light : ( )
(A) refraction
(B) reflection
(C) diffraction
(D) polarisation
Answer:
(A) refraction

Question 31.
A light ray travelling parallel to the principal axis of a concave lens after refraction ……………………. the principal focus : ( )
(A) converges at
(B) diverges from
(C) passes through
(D) none of these
Answer:
(B) diverges from

Question 32.
If u=-15 cm; v=30 cm; then magnification of the lens, m =? ( )
(A) +2
(B) -2
(C) ½
(D) -½
Answer:
(B) -2

Question 33.
The focal length of a lens suggested to a patient of hypermetropia is 100 cm. Its power is ( )
(A) 1D
(B) 2D
(C) O.5D
(D) -1D
Answer:
(A) 1D

Question 34.
The heights measured vertically down from points on principal axis are taken as ( )
(A) +ve
(B) -ve
(C) both+ve and -ve
(D) none of these
Answer:
(B) -ve

Question 35.
When an object is placed at 2F₁ of a biconvex lens, the image is formed ( )
(A) at F₂
(B) between F₂ and 2F₂
(C) at optic centre
(D) at 2F₂
Answer:
(D) at 2F₂

Question 36.
The size of the image formed by a convex lens when the object Is kept at its 2F₁ is: ( )
(A) enlarged
(B) diminished
(C) same size as object
(D) may be enlarged or diminished
Answer:
(C) same size as object

Question 37.
The point at which the refracted ray intersects the principal ax,s of a lens is called …………….. . ( )
(A) optic centre
(B) orthocentre
(C) geocentric
(D) principal focus
Answer:
(D) principal focus

Question 38.
A magnifying glass is a short focus ………………… lens : ( )
(A) concave
(B) convex
(C) Plano concave
(D) cylindrical
Answer:
(A) concave

Question 39.
The nearest point at which an object is seen clearly by the eye is called ………………. of the eye. ( )
(A) farthest point
(B) focal point
(C) nine point
(D) near point
Answer:
(D) near point

Question 40.
The distance between centre of curvature and curved surface of a lens is called …………….. . ( )
(A) principal axis
(B) focal length
(C) radius of curvature
(D) radius of gyration
Answer:
(C) radius of curvature

Question 41.
In case of a plane surface the radius of curvature approaches ( )
(A) 0
(B) +1
(C) -1
(D) infinity
Answer:
(D) infinity

Question 42.
The midpoint of a thin lens is called : ( )
(A) optic centre
(B) pole of lens
(C) principal focus
(D) centre of curvature
Answer:
(A) optic centre

Question 43.
The lens formula is; 1/f = ( )
(A) \(\frac{1}{u}-\frac{1}{v} \)
(B) \(\frac{1}{\mathrm{u}}+\frac{1}{\mathrm{v}} \)
(C) \(\frac{1}{\mathrm{v}}-\frac{1}{\mathrm{u}} \)
(D) \(\frac{u+v}{u v} \)
Answer:
(C) \(\frac{1}{\mathrm{v}}-\frac{1}{\mathrm{u}} \)

Question 44.
If a ……………………. lens is kept In a medium with refractive index less than the refractive index of the lens it behaves as a converging lens. ()
(A) convex
(B) concave
(C) cylindrical
(D) plano concave
Answer:
(A) convex

Question 45.
If you get an image which can’t be collected on a screen, but can be seen by the eye we call it ( )
(A) real image
(B) virtual image
(C) enlarged image
(D) diminished image
Answer:
(B) virtual image

Question 46.
The focal length of a lens can be increased by ( )
(A) keeping In vacuum
(B) keeping in water
(C) keeping in alcohol
(D) none of these
Answer:
(B) keeping in water

Question 47.
The watchmakers use a ……………………. lens to observe the parts of a watch ()
(A) concave
(B) piano-convex
(C) cylindrical
(D) biconvex
Answer:
(D) biconvex

Question 48.
The focal length of a lens depends on which of the following factors ( )
(A) radius of curvature
(B) material of the lens
(C) medium in which the lens is placed
(D) all the above
Answer:
(D) all the above

Question 49.
Two plano-convex lenses of focal lengths 10 cm and 20 cm are placed In contact with each other. The effective focal length of the combination is ()
(A) 10 cm
(B) 20 cm
(C) 200 cm
(D) 6.67 cm
Answer:
(D) 6.67 cm

Question 50.
A person is standing on the bank of a river. A fish inside water will see the persontobe …………… . ( )
(A) taller
(B) shorter
(C) original height
(D) depends on fish
Answer:
(A) taller

Question 51.
Which of the following lens act as converging lens? ( )
(A) Biconvex lens
(B) Plano-convex lens
(C) Concavo-convex
(D) All the above
Answer:
(D) All the above

Question 52.
D is the power of the lens, then focal length of the lens is ………………………. . ( )
(A) 100
(B) 10
(C) \(\frac{1}{100} \)
(D) \(\frac{1}{10} \)
Answer:
(A) 100

Question 53.
One of the uses of a Concave lens is ……………………….. .( )
(A) as eyepiece in microscope
(B) to focus the Sunlight at a point
(C) to correct Hypermetropia
(D) to correct Myopia
Answer:
(D) to correct Myopia

Question 54.
The radius of curvature of a plano-convex lens is doubled without changing the material or medium, Its focal length will be ( )
(A) double
(B) halfed
(C) remains same
(D) insufflcient data
Answer:
(A) double

Question 55.
An object is placed at a distance of 10 cm from a convex lens of focal length 10 cm. The image is formed at. ( )
(A) 10 cm
(B) 20 cm
(C) 100 cm
(D) Infinity
Answer:
(D) Infinity

Question 56.
A biconvex lens of focal length 20 cm is cut along a plane perpendicular to principal axis so as to make two plano-convex lenses. The focal length of each plano-convex lens is ( )
(A)20cm
(B) 10cm
(C) 40cm
(D) 5cm
Answer:
(C) 40cm

Question 57.
An object of height 2 cm is placed in front of a convex lens of focal length 15 cm at a distance of 45 cm. The height of the Image formed by the lens is ( )
(A) 1 cm
(B) 2 cm
(C) 3 cm
(D) 4 cm
Answer:
(A) 1 cm

Question 58.
In the lens displacement method of determining the focal length of a convex lens, the separation between the screen and the object should be ( )
(A) greater than or equlal to 2f
(B) greater than or equal to 4f
(C) greater than or equal to f²
(D) greater than or equal to f
Answer:
(B) greater than or equal to 4f

Question 59.
Dentist uses …………………….. to observe teeth. ( )
(A) concave mirror
(B) concave lens
(C) convex mirror
(D) plane mirror
Answer:
(A) concave mirror