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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.
| 751. |
A convex lens forms an image of an object on a screen ,The height of the image is`9cm`The lens is now disiplaced between the object on the screen.the height of this image is`4cm`.the distance between the object and the screen is `90cm`A. The distance between the two positions of the lens is `30cm`B. The distance of the object from the lens in its first position is`36cm`C. The height of the object is `6cm`D. The focal length of the lens is`21.6cm` |
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Answer» Correct Answer - B,C,D `h=sqrt(h_(1)h_(2)) rArrh=6cm` `m=(h_(1))/(h) =(v)/(u) rArr (-9)/(6) =(D-x_(1))/(-x_(1))` `x_(1)=36cm rArrx_(2)=D-x_(1) rArr x_(2)=54cm` ` d=54-36=18cm` `f=(D^(2)-d^(2))/(4D) rArr f=(90^(2)-18^(2))/(4xx90)` `f=((90+18)(90-18))/(4xx90) rArr f=(108xx72)/(4xx90)=(3xx72)/(10)=21.6cm` |
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| 752. |
A ray of light is incident at `50^(@)` on the middle of one of the two mirrorrs arranged at an angle of `60^(@)` between them . The ray then touches the second mirrorr, get reflected back to the first mirrorr, making an angle of incidence ofA. `50^(@)`B. `60^(@)`C. `70^(@)`D. `80^(@)` |
| Answer» Correct Answer - c | |
| 753. |
A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image will form atA. infinityB. poleC. focusD. 15 cm behined the mirror |
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Answer» Correct Answer - D (d) Given,u=-30cm and f=30 cm `(1)/(v)+(1)/(30)=(1)/(30)rArr(1)/(v)=(1)/(30)+(1)/(30)=(1)/(15)` Distance from the mirror,v=+15 cm |
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| 754. |
Which of the following could not produce a virtual imageA. Plane mirrorB. Convex mirrorC. Concave mirrorD. All the above can produce a virtual image |
| Answer» Correct Answer - d | |
| 755. |
which of the following can form diminished ,virtual and erect image of your face.A. Converging mirrorB. Diverging mirrorC. Converging lensD. Diverging lens |
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Answer» Correct Answer - B,D For obtained virutal image reflected /refractive rays must be diverging. |
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| 756. |
A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image will form atA. infinityB. poleC. focusD. 15 cm behind the mirror |
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Answer» Correct Answer - D Given, `u=-30 cm` f = 30 cm `(1)/(v)+(1)/(-30)=(1)/(30)rArr (1)/(v)=(1)/(30)+(1)/(30)=(1)/(15)` `therefore " "` Distance from the mirror, `v=+15 cm` |
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| 757. |
Focal length of a convex mirror is 10 cmA. image of an object placed at 20 cm is also at 20 cmB. image of an object placed at 10 cm is at infinityC. both (a) and (b) are wrongD. both (a) and (b) are correct |
| Answer» Correct Answer - C | |
| 758. |
A diminished virtual image can be formed only inA. Plane mirrorB. A concave mirrorC. A convex mirrorD. Concave-parabolic mirror |
| Answer» Correct Answer - c | |
| 759. |
A concave mirror has a focal length 20 cm. The distance between the two positions of the object for which the image size is double of the object size isA. 20 cmB. 40 cmC. 30 cmD. 60 cm |
| Answer» Correct Answer - A | |
| 760. |
An object is placed at a distance of 30 cm from a concave mirror and its real image is formed at a distance of 30 cm from the mirror. The focal length of the mirror isA. 15 cmB. 45 cmC. 30 cmD. 20 cm |
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Answer» Correct Answer - A (a) Given,u=-30 cm v=-30 cm Using relation, `(1)/(f)=(1)/(v)+(1)/(v)` `(1)/(-30)+(1)/(-30)=(1)/(f)` `therefore` Focal length of the mirror,f=-15 cm |
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| 761. |
A convex mirror of focal length f produced an image `(1//n)^(th)` of the size of the object. The distance of the object from the mirror isA. `(n-1)f`B. `((n-1)/n)f`C. `((n+1)/n)f`D. `(n+1)f` |
| Answer» Correct Answer - a | |
| 762. |
A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image will form atA. InfinityB. FocusC. PoleD. 15 cm behind the mirror |
| Answer» Correct Answer - d | |
| 763. |
An object is placed at 20 cm from a convex mirror of focal length 10 cm. The image formed by the mirror isA. Real and at `20 cm` from the mirrorB. Virtual and at 20 cm from the mirrorC. Virtual and at `20//3 cm` from the mirrorD. Real and at `20//3` cm from the mirror |
| Answer» Correct Answer - c | |
| 764. |
The image (of a real object) formed by a concave mirror is twice the size of the object. The focal length of the mirror is 20 cm. The distance of the object from the mirror is (are)A. `10 cm`B. `30 cm`C. `25 cm`D. `15 cm` |
| Answer» Correct Answer - A::B | |
| 765. |
Given a point source of light, which of the following can produce a parallel beam of lightA. Convex mirrorB. Concave mirrorC. Concave lensD. Two plane mirrors inclined at an angle of |
| Answer» Correct Answer - b | |
| 766. |
A convex mirror of focal length f produced an image `(1//n)^(th)` of the size of the object. The distance of the object from the mirror isA. `(n-1)f`B. `[(n-1)/(n)]f`C. `[(n+1)/(n)]f`D. `(n+1)f` |
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Answer» Correct Answer - A (a) Magnification, ` m=+1/n=-u/vs` `therefore` `v=-u/n` From the mirror formula, `1/f=(1)/((-(u)/(n)))+1/u` The distance of the object of the mirror, u=-(n-1)f |
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| 767. |
A concave mirror gives an image three times as large as the object placed at a distance of 20 cm from it. For the image to be real, the focal length should beA. 10 cmB. 15 cmC. 20 cmD. 30 cm |
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Answer» Correct Answer - B (b) Magnification, `m=(f)/(f-u) rArr -3=(f)/(f-(-20))` `rArr` The focal length of mirror, f=-15 cm |
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| 768. |
The image formed by a convex mirror of focal length `30 cm`. is a quarter of the object. What is the distance of the object from the mirror ?A. 30cmB. 60cmC. 90cmD. 120cm |
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Answer» Correct Answer - C Given, f=+30cm and `m=(1)/(4)` Magnification, `m=(f)/(f-u)` `therefore (30)/(30-u)=(1)/(4)` 30-y=120 `Rightarrowu=-90cm` |
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| 769. |
The image formed by a convex mirror of focal length `30 cm`. is a quarter of the object. What is the distance of the object from the mirror ?A. 30 cmB. 60 cmC. 90 cmD. 120 cm |
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Answer» Correct Answer - C Given, `f=+30 cm` and `m=(1)/(4)` Magnification, `m=(f)/(f-u)` `therefore " " (30)/(30-u)=(1)/(4)` `" " 30-u=120 rArr u =- 90 cm` |
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| 770. |
The focal length of a concave mirror is 50cm. Where an object be placed so that its image is two times and invertedA. 75 cmB. 72 cmC. 63 cmD. 50 cm |
| Answer» Correct Answer - a | |
| 771. |
The focal length of a concave mirror is 50cm. Where an object be placed so that its image is two times and invertedA. 55cmB. `-75cm`C. 65cmD. 85cm |
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Answer» Correct Answer - B Magnification,`m=(f)/(f-u)` Hence, `m=-2 and f=-50cm` `-2=(-50)/(-50-u) Rightarrow100+2u=-50` or `u=(-150)/(2)=-75cm` |
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| 772. |
The image formed by a convex mirror of focal length `30 cm`. is a quarter of the object. What is the distance of the object from the mirror ?A. 30 cmB. 90 cmC. 120 cmD. 60 cm |
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Answer» Correct Answer - B (b) Magnification, m`=(f)/(f-u)` `rArr (+(1)/(4))=(+30)/(+30-u)` `rArr` The distance of the object from the mirror,u=-90 cm |
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| 773. |
The focal length of a concave mirror is 50cm. Where an object be placed so that its image is two times and invertedA. 75 cmB. 60 cmC. 125 cmD. 50 cm |
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Answer» Correct Answer - A (a) In case of concave mirror, m=-2 Also, `m=(f)/(f-u)` `rArr -2=(-50)/(-50-u)` `therefore` Distance of the object from the mirror u = -75 cm |
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| 774. |
An object of size 7.5 cm is placed in front of a convex mirror of radius of curvature 25 cm at a distance of 40 cm. The size of the image should beA. 2.3 cmB. 1.78 cmC. 1 cmD. 0.8 cm |
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Answer» Correct Answer - B Magnification, `m=(l)/(O)=(f)/(f-u)` `therefore " " (l)/(7.5)=((R//2))/((R//2)-u)=((25//2))/((25//2)-(-40))` `therefore " "` The size of the image, `l=-1.78 cm` |
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| 775. |
A container is filled with water `(mu=1.33)` upto a height of 33.25 cm. A concave mirror is placed 15cm above the water level and the image of an object placed at the bottom is formed 25 cm below the water level. Focal length of the mirror is A. 10B. 15C. 20D. 25 |
| Answer» Correct Answer - C | |
| 776. |
A point object is moving on the principal axis of a concave mirror of focal length `24 cm` towards the mirror. When it is at a distance of `60 cm` from the mirror, its velocity is . `9 sec// cm` What is the velocity of the image at that instantA. `5 cm//sec` towards the mirrorB. `4 cm//sec` towards the mirrorC. `4 cm//sec` away from the mirrorD. `9 cm//sec` away from the mirror |
| Answer» Correct Answer - C | |
| 777. |
A point object is moving along principal axis of concave mirror with uniform velocity towards pole. Initially the object is at infinite distance from pole right side of the mirror as shown. Before the object collides with mirror, the number of times a which the distance between object and its image is `40 cm` are. .A. one timeB. two timesC. three timesD. data insufficient |
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Answer» Correct Answer - C |
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| 778. |
AB is an incident beam of light and CD is a reflected beam (the number of reflections for this may be 1 or more than 1) of light. AB and CD are separated by some distance (may be large). It is possible by placing what type of mirror on the right side. A. one plane mirrorB. one concave mirrorC. one convex mirrorD. none of these |
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Answer» Correct Answer - B |
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| 779. |
Assertion : Sun looks reddish at sunrise and sunset. Reason : Sun rays have to pass through larger distance in atmosphere.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true and reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - A At sunset and sunrise, the sun rays have to pass through a larger distance in the atmosphere. Most of the blue and other shorter wavelengths are removed by scattering. The least scattered light reaches our eyes, therefore the sun looks reddish. |
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| 780. |
Assertion : The clouds in the sky generally appear to be whitish. Reason : Diffraction due to clouds is efficient in equal measures its all wavelengths.A. If both, Assertion and Reason are true and the Reason is the correct explanation of the Assertion.B. If both, Assertion and Reason are true but Reason is not a correct explanation of the Assertion.C. If Assertion is true but the Reason is false.D. If both, Assertion and Reason are false. |
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Answer» Correct Answer - ( c) Here, Assertion is true but the reason is false. Whitish colour of cloud is due to the fact that all the colours of light are equally scattered by the droplets in the clouds. Hence, assertion is true but reason is false. |
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| 781. |
Line spectrum contains information aboutA. The atoms of the prismB. The atoms of the sourceC. The molecules of the sourceD. The atoms as well as molecules of the source |
| Answer» Correct Answer - b | |
| 782. |
The sun looks reddish at the time of sunrise and sunset.A. The sun is hottest at these timesB. Of the scattering of lightC. Of the effects of refractionD. Of the effects of diffraction |
| Answer» Correct Answer - b | |
| 783. |
When seen in green light, the saffron and green portions of our National Flag will appear to beA. BlackB. Black and green respectivelyC. GreenD. Green and yellow respectively |
| Answer» Correct Answer - b | |
| 784. |
STATEMENT-`1` A fish inside a pond will see a person standing outside taller than he is actually. `STATEMENT 2` Light bend away from the normal as it enters water from air.A. STATEMENT -`1`is true statement `2` is true,Statement -`2`is a correct explanation for statement -`1`B. STATEMENT -`1`is true statement `2` is true,Statement -`2`is a not a correct explanation for statement -`1`C. Statement -`1`is true,Statement -`2`is FalseD. Statement -`1`is False ,Statement -`2`is True |
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Answer» Correct Answer - C Since light bends towards normal on entering water form air. |
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| 785. |
The power of a lens used by short sighted person, is -2D. Find the maximum distance of an object which he can see without spectacles. |
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Answer» Power(P)=`1/("Focal length (m)")` Given,P=-2D `therefore` Focal length=`-1/2=0.5mrArrF=-50 cm` Hence, maximum distance of an object, which he can see without spectacles is 50 cm. |
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| 786. |
A ray of light is incident at an angle of `60^@` on one face of a rectangular glass slab of thickness `0.1 m`, and refractive glass slab of thickness `0.1 m`, and refractive index `1.5`. Calculate the lateral shift produced. |
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Answer» Correct Answer - 0.0513 m Here, `i_1 = 60^@, t = 0.1 m, mu = 1.5` As `(sin i_1)/(sin r_1) = mu` :. `sin r_1 = (sin i_1)/(mu) = (sin 60^@)/(1.5) = 0.5773` `r_1 = sin^-1 (0.5773) = 35.3^@` Lateral shift `= (t sin (i_1 - r_1))/(cos r_1)` =`(0.1 sin (60^@ - 35.3^@))/(cos 35.3^@) = (0.1 sin 24.7^@)/(cos 35.3^@)` =`(0.1 xx 0.418)/(0.816) = 0.0513 m`. |
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| 787. |
A plane wavefront AB is incident on a concave mirror as shown. Then,the reflected wavefront will be A. B. C. D. None of these |
| Answer» Correct Answer - C | |
| 788. |
The critical angle of a medium with respect to air is `45^(@)` . The refractive index of medium isA. 1.41B. 1.2C. 1.5D. 2 |
| Answer» Correct Answer - a | |
| 789. |
As the position of an object (u) reflected from a concave mirror is varied, the position of the image (v) also varies. By latting the u changes from 0 to `+ oo` the graph between v versus u will beA. B. C. D. |
| Answer» Correct Answer - A | |
| 790. |
An object of `1cm^(2)` face area is placed at a distance of 1.5m from a screen. How far from the object should a concave mirror be placed so that it forms `4 cm^(2)` image of object on the screen? Also, calculate the focal length of the mirror. |
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Answer» Correct Answer - `-1.5m, -1m` |
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| 791. |
The critical angle of light from medium A to medium B is `theta`. The speed of light in medium A is v. the speed of light in medium B isA. `v/(sin theta)`B. `v/(cos theta)`C. `v sin theta`D. `v cos theta` |
| Answer» Correct Answer - A | |
| 792. |
A ray incident at a point at an angle of incidence of `60^(@)` enters a glass sphere with refractive index `sqrt(3)` and it is reflected and refracted at the farther surface of the sphere. The angle between the reflected and refracted rays at this surface is:A. `120^(@)`B. `90^(@)`C. `60^(@)`D. `150^(@)` |
| Answer» Correct Answer - B | |
| 793. |
An object is placed at a distance u from a concave mirror and its real image is received on a screen placed at a distance of v from the mirror. If f is the focal length of the mirror, then the graph between 1/v versus 1/u isA. B. C. D. |
| Answer» Correct Answer - B | |
| 794. |
Light rays from a source are incident on a glass prism of index of refraction `mu` and angle of prism `alpha` At near normal incidence, the angle of deviation of the emerging rays isA. `(mu-2)alpha`B. `(mu-1)alpha`C. `(mu+1)alpha`D. `(mu+2)alpha` |
| Answer» Correct Answer - b | |
| 795. |
If `hat(i)` denotes a unit vector along incident light ray, `hat (r)`a unit vector along refracted ray into a medium of refraction index `mu` and `hat (n)` unit vector normal to boundary of medium directed towards incident medium, then law of refraction isA. `hat(i).hat(n)=mu(hat(r).hat(n))`B. `hat(i)xxhat(n)=mu(hat(n)xxhat(r))`C. `hat(i)xxhat(n)=mu(hat(r)xxhat(n))`D. `mu(hat(i)xxhat(n))=hat(r)xxhat(n)` |
| Answer» Correct Answer - c | |
| 796. |
A ray of light passes from vaccume 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. `2 cos^(-1)(n//2)`D. `2sin^(-1)(n//2)` |
| Answer» Correct Answer - C | |
| 797. |
When a monochromatic light ray is incident on a medium of refracive index`mu`with angle of incidence `theta_(1)`,the angle of refraction is `theta_(r).`if `theta_(i)` is changed slightly by`Deltatheta_(i)`,then the corresponding change in `theta_(r)`will be-A. `Delta Theta_(i)`B. `muDeltatheta_(i)`C. `(1)/(mu).cos theta_(1)/(cos theta_(r)).Delta theta_(i)`D. `mu.sin theta_(1)/(sin theta_(r)).Delta theta_(i)` |
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Answer» Correct Answer - C `mu=(sintheta_(i))/(sintheta_(r))` `sintheta_(r)=(1)/(mu)sintheta_(i)` Differentiate the equation with respect to`theta_(i)` `costheta_(r)""(d theta_(r))/(d theta_(i))=(1)/(mu) costheta_(i)` `d theta_(r)=(1)/(mu)(costheta_(i))/(costheta_(r))d theta_(r)` `Delta theta_(r)=(1)/(mu)(costheta_(i))/(costheta_(r))d theta_(r)Delta theta_(i)` |
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| 798. |
The refractive index of the material of a prism of `60^(@)` angle for yellow light is `sqrt(2)`. Calculate angle of minimum deviation, angle of incidence and angle of refraction. |
| Answer» Correct Answer - `30^@,45^@,30^@` | |
| 799. |
Find the power and type of the lens by which a person can see clearly the distant objects, if a person cannot see objects beyond `40cm`A. `-2.5D` and concave lensB. `-2.5D` convex lensC. `-3.5D` and concave lensD. `-3.5D` and convex lens |
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Answer» (a) Here, in this case the lens used by the person should form the image of distant object of `40cm` `:.u=oo,v=-40cm` and `1/f=1/v-1/u` `1/f=1/(-40)-1/(-oo)` `1/f=-1/40` Power `=1/f=-1/40=-2.5D` Negative sign shows that lens used is concave lens. |
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| 800. |
If a crown glass prims of refracing angle `10^(@)` have refractive indices for red and violet rays `1.514` and `1.523` respectively then find the dispersion caused by a crown glass prism.A. `0.07^(@)`B. `0.08^(@)`C. `0.09^(@)`D. `0.10^(@)` |
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Answer» (c) We know ,angular dispersion `=delta_(v)-delta_(R)=(mu_(v)-mu_(R))A=(1.523-1.514)xx10^(@)` `=0.009xx10^(@)=0.09^(@)` |
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