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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A ray of light passes through two slabs of same thickness. In the first slab `n_(1)` waves are formed and in the second slab `n_2`. Find refractive ` ` index of second medium with respect to first. |
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Answer» Correct Answer - A::B One wave means one wavelength . So, if t is the thickness of slab, `lambda` the wavelength and `n` the number of waves, then `nlambda=t rArr lambda =t/n ` or `lambda prop (1)/(n)` (as `t` is same) or `(lambda_(1))/(lambda_(2) )= (n_(2))/(n_(1)) ` Now refractive, index of second medium `w.r.t.` first medium is `._(1)mu_(2) = (lambda_(1))/(lambda_(2)) = (n_(2))/(n_(1))` |
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| 2. |
Find the position and nature of the image of an object 5 cm high and 10 cm in front of a convex lens of focal length 6 cm. |
| Answer» `v=+15`cm, The image is formed 1 cm behind the convex lens (on its right side), Real and inverted | |
| 3. |
An object is placed between f and 2f of a convex lens. Which of the following statements correctly describes its image?A. real, larger than the objectB. erect, smaller than the objectC. inveted, same size as objectD. virtual, larger than the object |
| Answer» Correct Answer - a)a) | |
| 4. |
A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed? |
| Answer» Correct Answer - 1 cm | |
| 5. |
Find the Odd one out:Critical angle, angle of incidence, angle of refraction, alternate angle |
| Answer» Alternate angle. Other are concerned with refraction. | |
| 6. |
Assertion: White light is incident on face AB of an isosceles right angled prism as shown. Colours, for which refractive index of material of prism is more than 1.414, will be able to emerge from the face AC. Reason:Total internal reflection cannot take place for the light travelling from a rarer medium to a denser medium.A. If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.B. If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.C. If both Assertion is true, but the Reason is false.D. If both Assertion is false but the Reason is true. |
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Answer» Correct Answer - D `i=45^@` For `mugtsqrt2 or 1.414 rArr theta_Clt45^@` `:.` They get TIR on face AC. |
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| 7. |
If the speed of light in ice is `2.3xx10^8 m//s,` what is its index of refraction? What is the critical angle of incidence for light going from ice to air? |
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Answer» Correct Answer - A::C `mu=c/v=(3xx10^8)/(2.3xx10^8)=1.3` `theta_C=sin^-1(1/mu)=sin^-1(1/1.3)=sin^-1(0.77)` |
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| 8. |
A light ray going through a prism with the angle of prism `60^@,` is founded to deviate at least by `30^@.` what Is the range of the refractive index of the prism? |
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Answer» Correct Answer - B `mu=sin(A+delta_m/2)/sin(A/2), delta_m=30^@` |
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| 9. |
The speed of light in wateris `2.25 xx 10^(8)`m/s. If the speed of light in vaccum be `3 xx 10^(8)`m/s, calculatethe refractive index of water |
| Answer» Correct Answer - `1.33` | |
| 10. |
Assertion:Minimum deviation by an equilateral prism of refractive index sqrt2 is `30^@.` Reason: It is from the relation, `mu=sin((A+delta_m)/2)/sin(A/2)`A. If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.B. If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.C. If both Assertion is true, but the Reason is false.D. If both Assertion is false but the Reason is true. |
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Answer» Correct Answer - A `A=60^@ and delta_m=30^@` Substituting the values, we get `mu=sqrt2` |
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| 11. |
A transparent solid sphere of radius `2 cm` and density `rho` floats in a transparent liquid of density `2rho` kept in a beaker. The bottom of the beaker is spherical in shape with radius of curvature `8 cm` and is silvered to make it concave mirror as shown in the figure. When an object is placed at a distance of `10 cm` directly above the centre of the sphere C, its final image coincides with it. Find h (as shown in the figure ), the height of the liquid surface in the beaker from the apex of the bottom. Consider the paraxial rays only. The refractive index of the sphere is `3//2` and that of the liquid is `4//3.` |
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Answer» Correct Answer - A::C `(V_i)/V=(rho_S)/(rho_L)=rho/(2rho)=1/2` i.e. half the sphere is inside the liquid. For the image to coincide with the object light should fall normally on te sphere. Using `(mu_2)/v-(mu_1)/u=(mu_2-mu_1)/R` twice, we have `(3//2)/(v_1)-1/(-8)=(3//2-1)/(+2)` `:. v_1=12 cm` Further, `(4//3)/(h-10)-(3//2)/8=(4//3-3//2)/(-2)` Solving this equation, we get `h=15 cm` |
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| 12. |
The figure shows the path of ray of light propagating from medium 1 to medium 2. The refractive index of medium 1 with respect to medium 2 is …………………………. . A. `(sin45^(@))/(sin60^(@))`B. `(sin60^(@))/(sin45^(@))`C. `(sin45^(@))/(sin30^(@))`D. `(sin30^(@))/(sin45^(@))` |
| Answer» Correct Answer - B | |
| 13. |
A ray of light passes from vaccum into a medium of refractive index n. If the angle of incidence is twice the angle of refraction, then the angle of incidence isA. `cos^-1(n//2)`B. `sin^-1(n//2)`C. `2cos^-1(n//2)`D. `2 sin^-1(n//2)` |
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Answer» Correct Answer - C `n=sini/(sin(i//2))=(2sin(i//2)cos(i//2))/sin(i//2)` Solving we get, `i=2 cos^-1(n//2)` |
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| 14. |
A telescope has an objective of focal length `50cm` and an eyepiece of focal length `5cm.` The least distance of distinct vision is `25cm.` The telescope is focused for distinct vision on a scale `2m` away from the objective. Calculate (a) magnification produced and (b) separation between objective and eyepiece. |
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Answer» Correct Answer - B::C Given, `f_0=50cm` and `f_e=5cm` For objective `1/v-1/-200=1/50` `:. v_0=200/3cm` `m_0=v_0/u_0=((200//3))/(-200)=-(1)/(3)` For eyepiece `1/-25-1/u_e=1/5` `:. u_e=-25/6cm` and `m_e=v_e/u_e=(-25)/-(25//6)=6` (a) Magnification, `m=m_0xxm_e=-2` (b) Separation between objective and eyepiece, `L=v_0+|u_e|=200/3+25/6=425/6` `=70.83cm` |
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| 15. |
Read the passage and Answer the following question:In, vacuum the velocity of light radiation with different wavelength is the same. But in a material medium, the velocity of different colour radiations is not the same and they travel with different paths. Due to this, the refractive index of the medium is different for different colours. If white beam of light is incident on a glass prism, the angle of refraction for different colours is different. When Sunlight is incident on a refracting surface, then it gets split into seven coloured spectrum and emerges out. The splitting of light into its component colours is called dispersion. Sir Isaac Newton was the first to use a glass prism to obtain the spectrum of Sunlight. A glass prism is transparent medium bounded by two plane surfaces inclined at an angle. When white light is dispersed into seven colours by a prism, different colours of light bend through different angles with respect to incident ray. Out of these seven colours, red light bends the least, while violet light bends the most. So, the rays of each colour emerge along different paths and becomes distinct. Hence, we get spectrum of seven - different colours. Q. What is spectrum ? |
| Answer» The band of coloured components of a light beam is called as Spectrum. | |
| 16. |
Read the passage and Answer the following question:In, vacuum the velocity of light radiation with different wavelength is the same. But in a material medium, the velocity of different colour radiations is not the same and they travel with different paths. Due to this, the refractive index of the medium is different for different colours. If white beam of light is incident on a glass prism, the angle of refraction for different colours is different. When Sunlight is incident on a refracting surface, then it gets split into seven coloured spectrum and emerges out. The splitting of light into its component colours is called dispersion. Sir Isaac Newton was the first to use a glass prism to obtain the spectrum of Sunlight. A glass prism is transparent medium bounded by two plane surfaces inclined at an angle. When white light is dispersed into seven colours by a prism, different colours of light bend through different angles with respect to incident ray. Out of these seven colours, red light bends the least, while violet light bends the most. So, the rays of each colour emerge along different paths and becomes distinct. Hence, we get spectrum of seven - different colours. Q. Which light deviates the least and which one deviates the most ? |
| Answer» When light is incident on a surface of a glass prism, the red light deviates the least, while violet light deviates the most. | |
| 17. |
An object is placed at a distance of 50cm from a concave lens of focal length 20cm. Find the nature and position of the image. |
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Answer» First of all we find out the position of the image which is given by the image distance v. Here, Object distance, u`=-50` cm (It is to the left of lens) Image distance, v=? (To be calculated) Focal length, f`=-20cm` (It is concave lens) Putting these values in the lens formula: `1/v-1/u=1/f` we get, `1/v-(1/-50)=1/(-20)` or `1/v+1/50=-1/20` or `1/v=-1/20-1/50` or `1/v=(-5-2)/(100)` or `1/v=-7/100` or `v=-100/7` So, Image distance, `v=-14.3` cm Thus, the image is formed at a distance of 14.3cm from the concave lens. The minus sign for image distance shows that the image is formed on the left side of the concave lens. We know that a concave lens always forms a virtul and erect image, so the nature of image is virtual and erect. |
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| 18. |
An object is 2m from a lens which forms an erect image one-fourth (exactly) the size of the object. Determine the focal length of the lens. What types of lens is this? |
| Answer» f`=-66.7` cm , Concave lens | |
| 19. |
Answer the following questions from the diagram: (a) How many times does the light undergo refractions ? (b) Which two angles are equal ? |
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Answer» (a) The light undergoes refraction 2 times. (b) angle of incidence (i) is equal to angle of emergence (e ). |
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| 20. |
Find the position of final image of an object O as shown in figure. |
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Answer» Correct Answer - A::B::C::D For plane surface, `h_(app)=muh` `=3/2xx10=15 cm` This first image is at a distance, `(15+3) cm` from the plane mirror. So, mirror will make its second image at a distance `18 cm` below the mirror or Now further applying, `d_(app)=d/mu=21/1.5=14 cm` below the plane surface. |
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| 21. |
At what distance eye E will observe the fourth image (after four refractions from plane surfaces) of object O from itself. |
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Answer» Correct Answer - A::B::C Total shift `=(1-1/mu_1)t_1+(1-1/mu_2)t_2` `=(1-2/3)10+(1-1/2)10` `=25/3 cm` `:.` Image distance `=50-25/3=125/3 cm` |
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| 22. |
If an object is placed at the centre of a glass sphere and it is seen from outside, then prove that its virtual image is also formed at centre. |
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Answer» Correct Answer - A All rays starting from centre pass undeviated as they fall normal to the surface. |
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| 23. |
A beam of parallel light rays is incident through the holes on one side of a box and emerges out through the holes on its opposite side as shown in the diagram below: Which of the following could be inside the box?A. a rectangular glass blockB. a concave lensC. a convex lensD. a glass prism |
| Answer» Correct Answer - c | |
| 24. |
What happens to the frequency, wavelength and speed of light that crosses from a medium with index of refraction `mu_1` to one with index of refraction `mu_2`? |
| Answer» Correct Answer - A::B::C::D | |
| 25. |
A prism can have a maximum refracting angle of `(theta_C=`critical angle for the material of prism )A. `60^@`B. `theta_C`C. `2 theta_C`D. slightly less than `180^@` |
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Answer» Correct Answer - C Condition of no emergence from opposite face is `Agt2 theta_C` |
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| 26. |
A ray of light travelling in glass `(mu_g=3//2)` is incident on a horizontal glass-air surface at the critical angle `theta_C.` If a thin layer of water `(mu_w=4//3)` is now poured on the glass-air surface. At what angle will the ray of light emerges into water at glass-water surface? |
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Answer» Correct Answer - A::C::D `sin theta_C=1/mu_1=2/3` Now, `u_1sini_1=u_2sini_2` or `mu_1sin theta_C=mu_2sin theta` `:. (3/2)(2/3) =(4/3)sin theta` or ` theta=sin^-1(3/4)` |
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| 27. |
A lens of focal length `12 cm` forms an upright image three times the size of a real object. Find the distance in cm between the object and image. |
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Answer» Correct Answer - A::C Virtual, magnified and erect image is formed by convex lens. Let `u=-x` Then, `v=-3x` Now, `1/(-3x)-1/-x=1/(+12)` `:. X=8 cm` Distance between object and image `=3x-x=2x=16 cm` |
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| 28. |
When a lens is inserted between an object and a screen which are fixed distance apart the size of the image is either `6` cm or `2/3 cm.` Find size of the object |
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Answer» Correct Answer - B::C `O=sqrt(I_1I_2)` (Displacement method) `=sqrt(6xx2/3)=2 cm` |
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| 29. |
A prism has refractive index `sqrt((3)/(2))` and refractive angle `90^@`. Find the minimum deviation produced by prismA. `60^@`B. `45^@`C. `30^@`D. `15^@` |
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Answer» Correct Answer - C `mu=(sin(A+delta_m)/2)/sin(A/2),` |
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| 30. |
Find the speed of light of wavelength `lambda =780nm` (in air) in a medium of refractive index `mu=1.55.` (b) What is the wavelength of this light in the given medium ? |
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Answer» Correct Answer - A::B::C::D (a) (` v=c/mu=(3.0xx10^8)/1.55=1.94xx10^8m//s` (b) `lambda_("medium")=(lambda_("air"))/(mu)=780/1.55=503nm` |
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| 31. |
The refractive index of water witih respect to air is `4/3`. The refractive index of air with respect to water will be:A. `1.75`B. `0.50`C. `0.75`D. `0.25` |
| Answer» Correct Answer - c) | |
| 32. |
Refractive index of glass with respect to water is `(9//8)`. Refractive index of glass with respect to air is `(3//2)`. find the refractive index of water with respect to air . |
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Answer» Correct Answer - C::D Given `._(w)mu_(g) = 9//8` and `._amu_(g) = 3//2` As `._amu_(g)xx._(g)mu_(w)xx._(w)mu_a=1` `:. (1)/(._(w)mu_(a))=._(a)mu_(w)=._amu_(g)xx._(g)mu_(w)= (._amu_(g))/(._(w)mu_(g))` `:. ._amu_(w) = (3//2)/(9//8) = (4)/(3)` |
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| 33. |
The splitting up of white light into colours is called __________. |
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Answer» The splitting of Sunlight into its component colours is called `ul("dispersion")`. The band of coloured of a light beam is called its spectrum. The various colours are Violet, Indigo, Blue, Green, Yellow, Orange and Red. |
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| 34. |
Which of the following can form a virtual image which is always smaller than the object?A. a plane mirrorsB. a convex lensC. a concave lensD. a concave mirror |
| Answer» Correct Answer - c | |
| 35. |
The lens A produces a magnification of, `-0.6` whereas lens produces a magnification of `+0.6`. a)What is the nature of lens A? What is the nature of lens B? |
| Answer» a) Convex lens b) Concave lens | |
| 36. |
The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power: A or B. |
| Answer» Lens A more power, It has shorter focal length. | |
| 37. |
Which of the two has a greater power, a lens of short length or a lens of large focal length? |
| Answer» Lens of short focal length | |
| 38. |
Fill in the following blanks with suitable words: a) Parallel rays of light are refracted by a convex lens to a point called the…………… b) The image in a convex lens depends uponthe distance of the ……………. From the lens. |
| Answer» a) Focus b) Object | |
| 39. |
The change in …………………… of light rays while going from one medium to another is called refraction. Light travels along a straight line path in a transparent medium. But, it does not travel in the same direction in all media. The direction of light rays change when it enters from one transparent to another as the velocity of light is different in different media. |
| Answer» The change in the `ul("direction")` of light rays while going from one medium to another obliquely is called refraction. | |
| 40. |
TRUE or FALSE:Incident ray and refracted rays are parallel to the normal. |
| Answer» Incident ray and refracted ray lie on the opposite side of normal. | |
| 41. |
Fill in the following blanks with suitable words: a) Light travelling along a normal is ………………………refracted. b) Light bends when it passes from water into air. We say that it is…………………………. |
| Answer» a) not b) refracted | |
| 42. |
A ray incident on the face of a prism is refracted and escape through an adjacent face. What is the maximum permissible angle of the prism, if it is made of glass with a refractive index of `mu=1.5`? |
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Answer» Correct Answer - A::D Condition of no emergence is, `Agt2 theta_C` `:. A_(max)=2 theta_C=2 sin^-1(1/1.5)` `=84^@` |
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| 43. |
A spherical mirror and a thin spherical lens have each a focal length of `- 15 cm`. The mirror and lens are likely to beA. both concave.B. both convexC. the mirror is concave but the lens is convex.D. the mirror is convex but the lens is concave. |
| Answer» Correct Answer - a) | |
| 44. |
If a spherical lens has a power of, `-0.25` D, the focal length of this lens will be:A. `-4 cm`B. `-400 nm`C. `-4 m`D. `-40 m` |
| Answer» Correct Answer - c) | |
| 45. |
The power of a lens is `+2.0`D. Its focal length should be:A. 100 cmB. 50 cmC. 25 cmD. 40 cm |
| Answer» Correct Answer - b | |
| 46. |
A diverging lens has a focal length of `0.10`m. The power of this lens will be:A. `+10.0`DB. `+1.0D`C. `-1.0`DD. `-10.0`D |
| Answer» Correct Answer - d) | |
| 47. |
A converging lens has a focal length of 50mm. What is the power of the lens? |
| Answer» Correct Answer - `+20 D` | |
| 48. |
What is the power of a convex lens whose focal length is 80 cm? |
| Answer» Correct Answer - `+1.25 D` | |
| 49. |
What is the power of a convex lens of focal length 0.5 m? |
| Answer» Correct Answer - `+ 2 D` | |
| 50. |
The focal length of a convex lens is 25 cm. What is its power? |
| Answer» Correct Answer - `+4D` | |