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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.
| 301. |
In the figure , a convex mirror of radius of curvature 20 cm is shown. An object O is placed in front of this mirror. Its ray diagram is shown. How many mistakes are there in the diagram (AB is its principal axis) A. 3B. 2C. 1D. 0 |
| Answer» Correct Answer - B | |
| 302. |
Assertion : A ray of light entering from glass to air suffers change in frequency. Reason : Velocity of light in glass is more than that ni air.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 - D Both, the Assertion and Reason are false. Frequency is that characteristic property of light which does bot change when light goes from one medium to another. So assertion is false. As glass is a denser medium in comparision to air, velocity of light in glass is less than that in air. |
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| 303. |
If an object moves towards a plane mirror with a speed v at an angle `theta` to the perpendicular to the plane of the mirror, find the relative velocity between the object and the image.A. vB. 2vC. `2v cos theta`D. `2v sin theta` |
| Answer» Correct Answer - c | |
| 304. |
Figure shows a cubical room ABCD with the wall CD as a plane mirror. Each side of the room is 3 m . We place a camera at the midpoint of the wall AB . At what distance should the camera be focussed to photograph an object placed at A. A. 1.5 mB. 3 mC. 6 mD. More than 6 m |
| Answer» Correct Answer - d | |
| 305. |
Water (with refractive index = 4/3) in a tank is `18 cm` deep. Oil of refraction index `7//4` lies on water making a convex surface of radius of curvature `R = 6 cm` as shown in Fig. Consider oil to act as a thin lens. An object `S` is placed `24 cm` above water surface. The location of its image is at `x cm` above the bottom of the tank. Then `x` is. .A. 1B. 2C. 3D. 4 |
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Answer» Correct Answer - B For refraction at air-oil interface, we have `u = -24 cm, mu_1 = 1, mu_2 = (7)/(4)`, `R = + 6 cm, v = v_1`(say) As `-(mu_1)/(u)+(mu_2)/(v)=(mu_2 - mu_1)/( R)` `:. -(1)/(-24)+(7//4)/(v_1)=((7//4) - 1)/(6) = (3)/(24)` or `(7)/(4 v_1)=(3)/(24)-(1)/(24)=(2)/(24)=(1)/(12)` or `v_1 = (12 xx 7)/(4) = 21 cm` This image will act as object for oil water interface. Taking refraction at oil-water interface, we have `u = + 21 cm, v = v_2, mu_1 = (7)/(4), mu_2 = (4)/(3), R = oo` As `-(mu_1)/(u)+(mu_2)/(v) = (mu_2 - mu_1)/(R )` `:. (-(7//4))/(21) +((4//3))/(v_2)=(4//3 - 7//4)/(oo) = 0` or `v_2 = 16 cm` Hence, `x = 18 - 16 = 2 cm`. |
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| 306. |
A prism having an apex angle `4^(@)` and refractive index 1.5 is located in front of a vertical plane mirror as shown in figure. Through what total angle is the ray is deviated after reflection from the mirror ? A. `176^(@)`B. `4^(@)`C. `178^(@)`D. `2^(@)` |
| Answer» Correct Answer - C | |
| 307. |
A man washign to get a picture of a Zebra photographed a white donkey after fitting a glass with black streaks onto the objective of his camera.A. The image will look like a white donkey on the photograph.B. the image will look like a Zebra on the photograph.C. the image will be more intense compared to the case no such glass is usedD. the image will be less intense compared to the case in which no such glass is used. |
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Answer» Correct Answer - A,D Every part of the lens works as a complete lens. |
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| 308. |
A screen is placed `90 cm` from an object. The image of the object on the screen is formed by a convex lens at two different location separated by `20 cm`. Determine the focal length of the lens. |
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Answer» Here, distance between object and screen, `D = 90 cm` Distance between two location of convex lens, `d = 20 cm, f = ?` As `f = (D^2 - D^2)/(4 D) :. f = (90^2 - 20^2)/(4 xx 90) =((90 + 20)(90 - 20))/(360) = (110 xx 7)/(36) = 21.4 cm`. |
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| 309. |
For a normal eye, the far point is at infinity and the near point of distinct vision is about `25 cm` in front of the eye. The cornea of the provides a converging power of about `40 dioptre` and the least converging power of eye lens behind the cornea is about `20 dioptre`. From this rough data, estimate the range of accommodation (i.e., the range of converging power of the eye lens) of a normal eye. |
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Answer» To observe objects at inifinity, the eye uses its converging power `= 40 + 20 = 60 D` `:.` Distance between cornea/eye lens and retina = focal length or eye lens `= (100)/(P) = (100)/(60) = (5)/(3) cm` To focus an object at the near point `u = -25 cm. v = 5//3 cm. f = ?` `(1)/(f)=-(1)/(u)+(1)/(v)=(1)/(25)+(3)/(5) = (1 + 15)/(25) = (16)/(25)` `f = (25)/(16) cm` Power `= (100)/(f)=(100)/(25/(16)) = 64 D` Power of eye lens `=64 - 40 = 24 D` Hence, range of accommodation of eye lens is roughly 20 to 24 dioptre. |
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| 310. |
An imaginary line joining the optical centre of the eye lens and the yellow point is called asA. Principal axisB. Vision axisC. Neutral axisD. Optical axis |
| Answer» Correct Answer - b | |
| 311. |
The light when enters the human eye experiences most of the refraction while passing throughA. CorneaB. Aqueous humourC. Vitrous humourD. Crystalline lens |
| Answer» Correct Answer - a | |
| 312. |
A person suffering from hypermetropia requires which type of spectacle lenses ?A. Concave lensB. Plano-concave lensC. Convexo-concave lensD. Convex lens |
| Answer» Correct Answer - d | |
| 313. |
The impact of an image on the retina remains forA. 0.1 secB. 0.5 secC. 10 secD. 15 sec |
| Answer» Correct Answer - a | |
| 314. |
The graph between the object distance along the X-axis and image distance along Y-axis for a convex lens isA. Straight lineB. CircleC. ParabolaD. Hyperbola |
| Answer» Correct Answer - d | |
| 315. |
Assertion: A red object appears dark in the yellow light . Reason: The red colour is scattered less.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
| Answer» Correct Answer - b | |
| 316. |
Assertion `:` The colour of the green flower seen through red glass appears to be dark. Reason `:` Red glass transmits only red light.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
| Answer» Correct Answer - a | |
| 317. |
Two point light sources are 24 cm apart. Where should a convex lens of focal length 9 cm be put in between them from one source so that the images of both the sources are formed at the same placeA. 6 cmB. 9 cm above water levelC. 12 cmD. 15 cm |
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Answer» Correct Answer - A |
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| 318. |
A glass lens is placed in a medium in which it is found to behave like a glass plate. Refractive index of the medium will beA. Greater than the refractive index of glassB. Smaller than the refractive index of glassC. Equal to refractive index of glassD. No case will be possible from above |
| Answer» Correct Answer - c | |
| 319. |
A thin lens of refractive index `1.5` has focal length of `15 cm` in air. When the lens is placed is a medium of refractive index (4)/(3), its focal length will become …..cm.A. 15 cmB. 10 cmC. 30 cmD. 60 cm |
| Answer» Correct Answer - d | |
| 320. |
Rays of light fall on a glass slab `(mugt1)` as shwon in figure. If `mu` at `A` is maximum and at `B` it is minimum, then what will happen to these rays? A. They will tilt towards `A`B. They will tilt towards `B`C. They will not deviateD. There will be total internal reflection |
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Answer» (c) For normal incidence, Whatever be refractive index. `l=0, r=0`, so there is no deviation of ray. |
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| 321. |
A convex lens makes a real image 4 cm long on a screen. When the lens is shifted to a new position without disturbing the object, we again get a real image on the screen which is 16 cm tall. The length of the object must beA. `1/4cm`B. `8cm`C. `12cm`D. `20cm` |
| Answer» (b) `0=sqrt(l_(1)l_(2))=sqrt(4xx16)=8cm` | |
| 322. |
The ray diagram could be correct A. If `n_(1)=n_(2)=n_(g)`B. If `n_(1)=n_(2)` and `n_(1) lt n_(g)`C. If `n_(1)=n_(2)` and `n_(1) gt n_(g)`D. Under no circumstances |
| Answer» Correct Answer - c | |
| 323. |
A convex lens makes a real image 4 cm long on a screen. When the lens is shifted to a new position without disturbing the object, we again get a real image on the screen which is 16 cm tall. The length of the object must beA. `1//4 cm`B. `8 cm`C. `12 cm`D. `20 cm` |
| Answer» Correct Answer - b | |
| 324. |
A thin convex lens of focal length 10 cm is placed in contact with a concave lens of same material and of same focal length. The focal length of combination will beA. ZeroB. InfinityC. 10 cmD. 20 cm |
| Answer» Correct Answer - b | |
| 325. |
Iluminance of `2.4 xx 10^(5)lm//m^(2)` of the surface is produced by sunlight falling normally on the surface of the earth. The distance of the earth the sun is `1.5 xx 10^(8)km`. Calculate the luminous intensity and luminous flux of the sun. |
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Answer» Correct Answer - `5.4 xx 106(27) cd, 6.78 xx 10^(28)lm` |
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| 326. |
A concave mirror is placed at the bottom of an empty tank with face upwards and axis vertical. When sunlight falls normally on the mirror, it is focussed at distance of `32cm` from the mirror. If the tank filled with water `(mu=4//3)` up to a height of `20cm`, then the sunlight will now get focussed atA. 16 cm above water levelB. 9 cm above water levelC. 24 cm below water levelD. 9 cm below water level |
| Answer» Correct Answer - B | |
| 327. |
A lamp is hanging at a height of `4 m` above a table. The lamp is lowered by `1 m` . The percentage increase in illuminace will beA. `40%`B. `64%`C. `78%`D. `92%` |
| Answer» Correct Answer - C | |
| 328. |
To prepare a print the time taken is 5 sec due to lamp of 60 watt at 0.25 m distance. If the distance is increased to 40 cm then what is the time taken to prepare the similar printA. `3.1 sec`B. `1 sec`C. `12.8 sec`D. `16 sec` |
| Answer» Correct Answer - c | |
| 329. |
A lamp is hanging 1 m above the centre of a circular table of diameter 1 m . The ratio of illuminaces at the centre and the edge isA. `(1)/(2)`B. `((5)/(4))^((3)/(2))`C. `(4)/(3)`D. `(4)/(5)` |
| Answer» Correct Answer - b | |
| 330. |
The intensity of direct sunlight on a surface normal to the rays is `I_(0)` . What is the intensity of direct sunlight on a surface, whose normal makes an angle of `69^(@)` with the rays of the sunA. `I_(0)`B. `I_(0)((sqrt(3))/(2))`C. `(I_(0))/(2)`D. `2I_(0)` |
| Answer» Correct Answer - c | |
| 331. |
Two stars situated at distances of 1 and 10 light years respectively from the earth appear to possess the same brightness. The ratio of their real brightness isA. `1 : 10`B. `10 : 1`C. `1:100`D. `100:1` |
| Answer» Correct Answer - c | |
| 332. |
A ray of light travelling inside a rectangular glass block of refractive index `sqrt(2)` is incident on the glass–air surface at an angle of incidence of `45^(@)`. The refractive index of air is 1. Under these conditions the rayA. Will emerge into the air without any deviationB. Will be reflected back into the glassC. Will be absorbedD. Will emerge into the air with an angle of refraction equal to `90^(@)` |
| Answer» Correct Answer - d | |
| 333. |
The XY plane is the boundary between two tranparednt media. Medium 1 with `z ge 0` has a refraxtive index of `sqrt2` and medium 2 with `z le 0` has a refractive index of `sqrt3`. A ray of light in medium 1 given by the vector `6sqrt(3)hat(i)+8sqrt(3)hat(j)-10hatk` is incident on teh plane of separation. Find the unit vector in the direction of teh refracted ray in medium 2.A. `60^(@)`B. `75^(@)`C. `30^(@)`D. `45^(@)` |
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Answer» Correct Answer - 4 Normal to the plane is z-axis `costheta_(1)=(A_(z))/(A)=(10)/(20)=(1)/(2),theta_(1)=60` `mu_(1)Sintheta_(1) rArr mu_(2) sintheta_(2) rArr sqrt(2)xx(sqrt(3))/(2)=sqrt(3)sintheta_(2) rArr theta_(2)=45^(@)` |
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| 334. |
A wave is reflected from a rigid support. The change in phase on reflection will beA. `0`B. `pi/2`C. `pi`D. `2pi` |
| Answer» Correct Answer - c | |
| 335. |
A watch shows time as `3:25` when seen through a mirror, time appeared will beA. `8 : 35`B. `9 : 35`C. `7 : 35`D. `8 : 25` |
| Answer» Correct Answer - a | |
| 336. |
If an observer is walking away from the plane mirrorr with `6m//sec` . Then the velocity of the image with respect to observer will beA. 6m / secB. `-6m//sec`C. 12 m/secD. 3m/sec |
| Answer» Correct Answer - c | |
| 337. |
A light ray is incident on a horizontal plane mirror at an angle of `45^(@)`. At what angle should a second plane mirror be placed in order that the refelcted ray finally be reflected horizontally form the second mirror, as shown in figure A. `theta=30^(@)`B. `theta=24^(@)`C. `theta=22.5^(@)`D. `theta=67.5^(@)` |
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Answer» (c) From figure `CD=` emergent ray and `CD` is parallel to `PQ` and `BC` is a line intersecting these parallel lines, So, `/_DCB/_CBQ=180^(@)` `/_DCN+/_NCB+/_CBQ=180^(@)` `alpha+alpha+45^(@)=180^(@)` `alpha=67.5^(@)` But `/_NCS=90^(@)` So, second mirror is at an angle of `22.5^(@)` with horizontal . |
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| 338. |
Assertion`:` When an objecct is placed between two plane parallel mirrorrs, then all the images found are of equal intensity. Reason`:` In case of plane parallel mirrorrs, only two images are possible.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
| Answer» Correct Answer - d | |
| 339. |
The mirror are inclined at angle of `50^(@)`. The number of images formed for an object placed in between the mirrors isA. 5B. 6C. 7D. 8 |
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Answer» Correct Answer - B We know that the relation for number of images formed for an object placed between the mirror, `n=(360^(@))/(theta)-1` Given, `theta=50^(@)` Now, Number of images, `n=(360)/(50^(@))-1=7.2=6.2=6` |
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| 340. |
If two mirrors are inclined at some angle and an object is placed between the mirrors and there are 7 images formed for an object. Then, what is angle between the mirrors?A. `54^(@)`B. `50^(@)`C. `60^(@)`D. `64^(@)` |
| Answer» Correct Answer - (b) | |
| 341. |
Assertion `:` The mirrorrs used in search lights are parabolic and not concave spherical. Reason `:` In a concave spherical mirrorr the image formed is always virtual.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
| Answer» Correct Answer - c | |
| 342. |
Why are mirrors used in search lights parabolic and not concave sphrical ? |
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Answer» In search lights, we need an intense parallel beam of light. If a source is placed at the focus of a concave spherical mirror, only paraxial rays are rendered parallel. Due to large aperture of mirror, marginal rays give a divergent beam. But in case of parabolic mirror, when source is at the focus, beam of light produced over the entire cross-section of the mirror is a parallel beam. |
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| 343. |
A medium shows relation between i and r as shown. If speed of light in the medium is nc then value of n is A. 1.5B. 2C. `2^(-1)`D. `3^(-1//2)` |
| Answer» Correct Answer - d | |
| 344. |
Two plane mirrors are inclined at an angle of `72^(@)` . The number of images of a point object placed between them will beA. 2B. 3C. 4D. 5 |
| Answer» Correct Answer - c | |
| 345. |
The magnifying power of a compound microscope isA. The focal length of objective lens is increased and that of eye lens is decreasedB. The focal length of eye lens is increased and that of objective lens is decreasedC. Focal lengths of both objective and eye-piece are increasedD. Focal lengths of both objective and eye-piece are decreased |
| Answer» Correct Answer - d | |
| 346. |
For which of the following colour, the magnifying power of a microscope will be maximumA. White colourB. Red colourC. Violet colourD. Yellow colour |
| Answer» Correct Answer - c | |
| 347. |
You are given four sources of light each one providing a light of a single colour-red, blue,green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is `90^@`. Which of the folowing statements is correct it the source of yellow light is replaced with that of other lights without changing the angle of incidence ?A. The beam of red light would undergo total internal reflection.B. The beam of red light would bend toward normal while it gets refracted through the second medium.C. The beam of blue light would undergo total internal reflection.D. The beam of green light would bend away from the normal as it gets refracted through the second medium. |
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Answer» Correct Answer - C Here, for yellow light, `r = 90^(@)` when `I = C`. As I kept same, C must be smaller for total internal reflection. From `mu = (1)/(sinC),C` will be smallest for blue colour. Therefore, blue light would undergo total internal reflection. |
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| 348. |
A large temple has a depression in one wall.On ht floor plan is appers as a indentation having spherical shape of radius `2.50m`A worshipper stands one the center line of the depression,`2.00`m out from its deepest point,and whispers a prayers.Where is the sound concentrated after reflection fromt he back wall of the depression? |
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Answer» Correct Answer - `((10)/(3)m)` wall will act as concave mirror `(1)/(v)+(1)/(u)=(1)/(f)implies (1)/(v)+(1)/(u)=(2)/(R )rArr(1)/(v)+(1)/(-2)=(2)/(-2.5)` `(1)/(v)=(2)/(-2.5)+(1)/(2)rArr(1)/(v)=(-8+5)/(10)` `(1)/(v)=(-3)/(10)` `v=(-10)/(3)m` |
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| 349. |
The focal length of lens of refractive index `1.5` in air is `30 cm` When it is immersed in water of refractive index `(4)/(3)` ,then its focal length will beA. 0.15mB. 0.30mC. 0.45mD. 1.20m |
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Answer» Correct Answer - D `therefore (1)/(f)=[(mu_(1))/(mu_(2))-1][(1)/(R_(1))-(1)/(R_(2))]` Given `R_(1)=0.30m,` `R_(2)=-0.30m, mu_(1)=3//2, mu_(2)=4//3` `[(1)/(f)=[(3//2)/(4//3)-1][(1)/(30)-((-1)/(0.30)]]` By putting values, f=1.20m. |
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| 350. |
The diameter of the eye ball of a normal eye is about 2.5cm. The power of the eye lens varies fromA. 9D to 8DB. 40D to 32DC. 44D to 40DD. None of these |
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Answer» Correct Answer - C An eye see distant objects with full releaxtion. So, `(1)/(2.5xx10^(-2))-(1)/(-oo)=(1)/(f)` or `P=(1)/(f)=(1)/(2.5xx10^(-2)=40D` An eye see an object at 25cm with strain `(1)/(2.5xx10^(-2))-(1)/(25xx10^(-2))=(1)/(f)` `therefore P=(1)/(f)=40+4=44D` The power of the eye lens various from 44D to 40D. |
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