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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.
| 251. |
If refractive index of red, violet and yellow light are `1.42, 1.62` and `1.50` respectively for a medium. Its dispersive power will beA. 0.4B. 0.3C. 0.2D. 0.1 |
| Answer» Correct Answer - a | |
| 252. |
Two lenses having `f_(1):f_(2)=2:3` has combination to make no dispersion. Find the ratio of dispersive power of glasses usedA. `2 : 3`B. `3 : 2`C. `4 : 9`D. `9 : 4` |
| Answer» Correct Answer - a | |
| 253. |
Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.A. medium on both sides is sameB. angle of incidence is `90^(@)`C. angle of incidence is `0^(@)`D. medium on other side is rarer |
| Answer» Correct Answer - A::C | |
| 254. |
The objective of telescope `A` has a diameter `3` times that of the objective of telescope `B`. How much greater amount of light is gathered by `A` compared to `B` ? Show that range of `A` is three times the range of `B`. |
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Answer» As diameter of objective of `A` is `3` times that of `B`, its area of cross section is `9` times that of `B`. Therefore, light gathering capacity of `A` is `9` times that of `B`. Now, range tells us how far away a star of some standard brightness can be spotted by the telescope. As Intensity `prop (1)/(("distance")^(2))` therefore, when distance of star is `3` times, the intensity would reduce to `(1)/(9) th`. As light gathering capacity of `A` is `9` times that of `B`, the star whose distance is `3` times can just be seen by `A`. Hence rage of `A` is three times that of `B`. |
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| 255. |
Which colour deviates (i) most (ii) least on passing through a prism ? |
| Answer» Violet colour suffers maximum deviation and red colour suffers the least deviation. | |
| 256. |
For which colour, `mu` of material of a prism is (i) minimum (ii) maximum ? |
| Answer» `mu` is minimum for red colour and `mu` is maximum for violet colour. | |
| 257. |
A light ray is incident perpendicularly to one face of a `90^circ` prism and is totally internally reflected at the glass-air interface. If the angle of reflection is `45^circ`, we conclude that the refractive index n A. Less than 1.41B. Equal to 1.41C. Greater than 1.41D. None of the above |
| Answer» Correct Answer - c | |
| 258. |
A ray of light travelling in a transparant medium falls on a surface separating the medium from air at an angle of incidence of `45degree`. The ray undergoes total internal reflection. If n is the refractive in index of the medium with respect to air, select the possible value (s) of n from the following:A. 1.2B. `4//3`C. 1.4D. 1.5 |
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Answer» Correct Answer - C (c ) We have, sini`gtsintheta_(c)` `therefore` `sin45^(@)gt1/nor1/sqrt2gt1/n` `ngtsqrt2orngt1.414` |
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| 259. |
For total internal reflection to take place, the angle of incidence `i` and the refractive index `mu` of the medium must satisfy the inequalityA. `1/(sin i) lt mu`B. `1/(sin i) gt mu`C. `sin I lt mu`D. `sin I gt mu` |
| Answer» Correct Answer - a | |
| 260. |
The phenomena of total internal reflection is seen when angle of incidence isA. `90^(@)`B. Greater than critical angleC. Equal to critical angleD. `0^(@)` |
| Answer» Correct Answer - b | |
| 261. |
Total internal reflection of a ray of light is possible when the (`i_(c) =` critical angle, `i=` angle of incidence)A. Ray goes from denser medium to rarer medium and `i lt i_(c)`B. Ray goes from denser medium to rarer medium and `i gt i_(c)`C. Ray goes from rarer medium to denser medium and `i gt i_(c)`D. Ray goes from rarer medium to denser medium and `i lt i_(c)` |
| Answer» Correct Answer - b | |
| 262. |
In the figure shown , for an angle of incidence `45^(@)`, at the top surface , what is the minimum refractive index needed for the internal reflection at vertical face ? A. `(sqrt(2)+1)/(2)`B. `sqrt(3/2)`C. `sqrt(1/2)`D. `sqrt(2)+1` |
| Answer» Correct Answer - b | |
| 263. |
A convex mirror and a concave mirror of radius 10cm each are placed 15cm apart facing each other. An object is placed midway between them. If the reflection first takes place in the concave mirror and then in convex mirror, the position of the final image is |
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Answer» Correct Answer - Image is formed at the pole of convex mirror just behing it |
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| 264. |
A bird is flying up at an angle `sin^(-1)(3//5)` with the horizontal. A fish in a pond looks at that bird when it is vertically above the fish. The angle at which the bird appears to fly (to the fish) is `[mu_(w) = 4//3]`A. `sin^(-1)(3//5)`B. `sin^(-1)(4//5)`C. `45^(@)`D. `sin^(-1)(9//16)` |
| Answer» Correct Answer - B | |
| 265. |
A light ray `I` is incident on a plane mirror `M`.The mirror is rotated in the direction as shown in the figure by an arrow at frequency `(9)/(pi) "rev"//"sec"`,The light reflected by the mirror is received on the wall `W` at a distance `10m`from the axis of rotation .When the angle of incidence becomes `37^(@)`find the speed of the spot (a point) on the wall? A. 10 m/sB. 1000 m/sC. 500 m/sD. 20 m/s |
| Answer» Correct Answer - C | |
| 266. |
Ability of the eye to see objects at all distances is calledA. Binocular visionB. MyopiaC. HypermetropiaD. Accommodation |
| Answer» Correct Answer - d | |
| 267. |
In Fig., there are two convex lenses `L_1 and L_2` having focal lengths `F_1` and `F_2` respectively. The distance between `L_1` and `L_2` will be : .A. `F_1`B. `F_2`C. `F_1 + f_2`D. `F_1 - F_2` |
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Answer» Correct Answer - C `L_1` will converge the parallel ray at its focus , `L_2` will render it parallel only when the refracted ray starts from the focus of `L_2`. `:.` Distance between `L_1 L_2 = F_1 + F_2`. |
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| 268. |
A man is standing in a room and a plane mirror is fixed on the wall in fornt of him.The height of the wall is `H`.Man has to see the complete image of wall behing him at a time When the man is standing at the midddle of the room i.e at position `2`,the minimum length of the mirror required isA. `H`B. `H//2`C. `H//3`D. `H//4` |
| Answer» Correct Answer - C | |
| 269. |
A man is standing in a room and a plane mirror is fixed on the wall in front of him.The height of the wall is `H`.Man has to see the complete image of wall behind him at a time When the man is standing near wall i.e at a position `1`,the minimum length of the mirror required isA. `H`B. `H//2`C. `H//3`D. `H//4` |
| Answer» Correct Answer - B | |
| 270. |
Stars are twinkling due toA. DiffractionB. ReflectionC. RefractionD. Scattering |
| Answer» Correct Answer - c | |
| 271. |
An astronomical telescope has an angular magnification of magnitude 5 for distant object. The separation between the objective and the eyepiece is 36 cm and the final image is formed at infinity. The focal length `f_(0)` of the objective and the focal length `f_(0)` of the eyepiece areA. `f_(o)=45 cm and f_(e)=-9cm`B. `f_(o)=-7.2 cm and f_(e)=5cm`C. `f_(o)=50 cm and f_(e)=10cm`D. |
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Answer» Correct Answer - D (d) In this case, `abs(m)=f_(0)/(f_(e))=5` and the length of telescope = `f_(0)+f_(e)=36` On solving Eqs. (i) and (ii), we get `f_(e)=6 cm, f_(0)=30 cm` |
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| 272. |
An astronomical telescope has an angular magnification of magnitude 5 for distant object. The separation between the objective and the eyepiece is 36 cm and the final image is formed at infinity. The focal length `f_(0)` of the objective and the focal length `f_(0)` of the eyepiece areA. `f_(o) = 45 cm and f_(e) = -9cm`B. `f_(o) = -7.2 cm and f_(e) = 5 cm`C. `f_(o) = 50 cm and f_(e) = 10 cm`D. `f_(o) = 30 cm and f_(e) = 6 cm` |
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Answer» Correct Answer - D In this case, `|m|=(f_(o))/(f_(e ))=5` …..(i) and length of telescope `= f_(o)+f_(e )=36` …..(ii) On solving Eqs. (i) and (ii), we get `f_(e )=6 cm, f_(o)=30 cm` |
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| 273. |
An astronomical telescope has an angular magnification of magnitude `5` for distant object. The separation between the objective and eyepiece is `36cm` and the final image is formed at infinity. Determine the focal length of objective and eyepiece.A. `f_0 = 45 and f_e = -9 cm`B. `f_0 = 50 cm and f_e = 10 cm`C. `f_0 = 7.2 cm and f_e = 5 cm`D. `f_0 = 30 cm and f_e = 6 cm`. |
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Answer» Correct Answer - D Here, Angular magnification of telescope `= (f_0)/(f_e) = 5`, `:. f_0 = 5 f_e` …(i) Now, `f_0 + f_e = 36 cm` ….(ii) On solving (i) and (ii), we get `5 f_e + f_e = 36 cm` `f_e = 6 cm, f_0 = 30 cm`. |
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| 274. |
A person can not see an object lying beyond`80cm`whereas a normal person can easily see the object distant`160cm`.The focal lengthand the nature of the lens used to rectify this defect will be-A. `-160cm`conacaveB. `160cm`convexC. `60cm`concaveD. `160cm`convex |
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Answer» Correct Answer - 1 `because (1)/(f)=(1)/(v)-(1)/(u)` `(1)/(f)=-(1)/(80)+(1)/(60)` `:.f=-160` |
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| 275. |
The focal length of the objective and the eyepiece of a microscope are`4mm`and `25mm`respectively.If the final image is formed at infinity and the length of the tube is `16cm`the magnifying power of the microscope will beA. `-327.5`B. `-32.75`C. `-3.275`D. `32.75` |
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Answer» Correct Answer - 1 `M=-(V_(0))/(u_(0))(D)/(f_(e))` `u_(0)=-((54)/(131))cm` `M=(-13.5)/(((54)/(131)))xx(25)/(2.5)=-327.5` |
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| 276. |
A telescope consisting of an objectives of focal length`60cm`and a single -lens eyepiece of focal length`5cm` is focussed at a distant object in such a way that parallel rays emerge from the eye piece .If the object subtends an angle of `2^(@)`at the objectives ,then the angular width of the image will be - (1) `10^(@) (2) 24^(@) (3)50^(@) (4)1//6^(@)` |
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Answer» `m=(f_(0))/(f_(e))=(beta)/(alpha)` `:. beta=alpha (f_(0))/(f_(e))=2xx(60)/(5)=24^(@)` |
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| 277. |
The focal length of the objectives and the eyepiece of an astronomical telescope are `16cm`and`2cm` respectively .A planet is viewed with its help ,thenA. The angular magnification of the planet is`-800`B. The image of the planet is invertedC. the distance between the objectives and the eye piece of`16.02`D. All the above |
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Answer» Correct Answer - 4 `therefore` Distance between objectives and eyepiece `=f_(0)+f_(e)=16.02m` Angular magnification`M=-(f_(0))/(f_(e))` or`M=(-16)/(0.02)=-800` The image formed by a telescope is always inverted. |
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| 278. |
Diameter of the moon is `3.5xx10^(3)km`and its distance from earth is`3.8xx10^(5)km`.It is seen by a telescope whose objectives and eyepiece have focal lengths`4`mand `10cm`respectively.The angular diameter fo the image of the moon will be nearly- (1) `5^(@)` ,(2) `10^(@)` ,(3)` 20^(@)` ,(4)`25^(@)` |
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Answer» `M=-(f_(0))/(f_(e))=-(400)/(10)-40` Angle substanded by the moon at the objective ` =(3.5xx10^(3))/(3.8xx10^(5))=0.009 radian` Thus the angular diameter of the image `=Mxx"visual angle"` `=40xx0.009=0.36radian` `=(0.36xx180)/(3.14)=20^(@)` |
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| 279. |
A simple telescope, consisting of an objective of focal length 60 cm and a single eye lens of focal length 5 cm is focussed on a distant object in such a way that parallel rays comes out from the eye lens. If the object subtends an angle `2^(@)` at the objective, the angular width of the imageA. `10^(@)`B. `24^(@)`C. `50^(@)`D. `1//6^(@)` |
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Answer» Correct Answer - B |
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| 280. |
The diameter of the moon is `3.5xx10^(3)km` and its distance from the earth is `3.8xx10^(5) km`. It is seen by a telescope having the focal length of the objective and the eye-piece as `4m` and `10cm` respectively. The diameter of the image of the moon will be approximatelyA. `15^(@)`B. `20^(@)`C. `30^(@)`D. `35^(@)` |
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Answer» Correct Answer - B |
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| 281. |
Three prisms of crown glass, each have angle of prism `9^(@)` and two prisms of flint glass are used to make direct vision spectroscope. What will be the angle of flint glass prisms if `mu` for flint is `1.69` and `mu` for crown glass is `1.53` ?A. `11.9^(@)`B. `16.0^(@)`C. `15.3^(@)`D. `9.11^(@)` |
| Answer» Correct Answer - a | |
| 282. |
The distance of the moon from earth is `3.8 xx 10^(5) km`. The eye is most sensitive to light of wavelength `5500 Å`. The separation of two points on the moon that can be resolved by a 500 cm telescope will beA. 51 mB. 60 mC. 70 mD. All the above |
| Answer» Correct Answer - A | |
| 283. |
To which wavelength of lights is our eye most sensitive ? In which region does this wavelength lie ?A. 4500 ÅB. 5500 ÅC. 6500 ÅD. Equally sensitive for all wave lengths of visible spectrum |
| Answer» Correct Answer - b | |
| 284. |
If the wavelength of incident light on a concave mirror is increased, how will the focal length of the mirror change ? |
| Answer» The focal length of the mirror does not change on changing the wavelength of light incident on it. This is because `f = R//2`, i.e., `f` depends only one radius of curvature of the mirror. | |
| 285. |
Two thin lenses of focal length `f_(1)` and `f_(2)` are in contact and coaxial. The power of the combination isA. `f_(1)+f_(2)`B. `(f_(1)f_(2))/(f_(1)+f_(2))`C. `1/2 (f_(1)+f_(2))`D. `(f_(1)+f_(2))/(f_(1)f_(2))` |
| Answer» Correct Answer - d | |
| 286. |
The surfaces of the sun glasses (goggles) are curved, yet their power may be zero. Why ? |
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Answer» Both the surfaces of sun glasses are curved. Also, `R_1 = R_2` As `P = (mu - 1)((1)/(R_1) - (1)/(R_2))` `:. P = 0`. |
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| 287. |
Assertion:Although the surfaces of goggle lens are curved, It does not have any power. Reason: In case of goggles, both the curved surfaces have equal radii of curvature and have centre of curvature on the same side.A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - A (a) `therefore P=1/f=(mu-1)(1/R-1/R)=0` |
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| 288. |
When light travels from air to water and from water to glass, again from glass to `CO_(2)` gas and finally through air. The relation between their refractive indices will be given byA. `._(a)n_(w)xx._(w)n_(gl)xx._(gl)n_("gas")xx._("gas")n_(a)=1`B. `._(a)n_(w)xx_(w)n_(gl)xx._("gas")n_(gl)xx._(gl)n_(a)=1`C. `._(a)n_(w)xx._(w)n_(gl)xx._(gl)n_("gas")=1`D. There is no such relation |
| Answer» Correct Answer - a | |
| 289. |
Assertion When a wave travels from a denser to a rarer medium, its amplitude increases. Reason In a rarer medium, speed of wave is moreA. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - A (a) `A_(t)=((2v_(2))/((v_(1)+v_(2))A_(i)` If `v_(2)htv_(b)` then `A_(t)gtA_(i)` |
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| 290. |
A slab of glass, of thickness 6 cm and refractive index 1.5, is placed in front of a concave mirror, the faces of the slab being perpendicular to the principal axis of the mirror. If the radius of curvature of the mirror is 40 cm and the reflected image coincides with the object, then the distance of the object from the mirror isA. 30 cmB. 22 cmC. 42 cmD. 28 cm |
| Answer» Correct Answer - c | |
| 291. |
A divergent lens will produceA. Always a virtual imageB. Always real imageC. Sometimes real and sometimes virtualD. None of the above |
| Answer» Correct Answer - a | |
| 292. |
Assertion A diverging lens (in air) cannot be made more diverging whatever be the medium we choose completely immerse the lens. Reason The minimum refractive index of any medium is 1.A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - A (a) When a diverging lens is immersed in a liquid, then its diverging power will either decrease or it will become converging. |
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| 293. |
Assertion In front of a concave mirror, a point object is placed between focus and centre of curvature. If a glass slab is placed between object and mirror, then image from mirror may become virtual. Reason Glass slab always makes a virtual image of a real object.A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - C (c) Glass slab will shift the object towards mirror. If it comes between pole and focus the image will become virtual. |
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| 294. |
A convex lens of crown glass (n =1.525) will behave as a divergent lens if immersed inA. Water (n=1.33)B. In a medium of `n=1.525`C. Carbon disulphide n=1.66D. It cannot act as a divergent lens |
| Answer» Correct Answer - c | |
| 295. |
Assertion If a lens is immersed in a liquid its nature will change ie., convex will behave concave and vice-versa. Reason If both sides of a lens medium is same, then object can be placed on either side of the lens, image distance remains sameA. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - D (d) Nature of lens will change only, if refractive index of liquid is more than that of material of lens. |
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| 296. |
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 reflectionB. The beam of red light would bend towards normal while it gets refracted through the second mediurnC. The beam of blue light would undergo total internal reflectionD. 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 (c ) According to VIBGYOR, among all given sources of light, the blue light have smallest wavelength. According to Cauchy relationship, smaller the wavelength higher the refractive index and consequently smaller the critical angle. So corresponding to blue colour, the critical angle is the least which fascilitates total internal,reflection for the beam of blue light. The beam of green light would also undergo total internal reflection. |
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| 297. |
Refractive index for a material for infrared light isA. Equal to that of ultraviolet lightB. Less than for ultraviolet lightC. Equal to that for red colour of lightD. Greater than that for ultraviolet light |
| Answer» Correct Answer - b | |
| 298. |
A rectangular tank of depth 8 meter is full of water `(mu=4//3)`, the bottom is seen at the depthA. 6 mB. 8/3 mC. 8 cmD. 10 cm |
| Answer» Correct Answer - a | |
| 299. |
A beam of light propagating in medium A with index of refraction n ( A ) passes across an interface into medium B with index of refraction n ( B ). The angle of incidence is greater than the angle of refraction, v ( A ) and v ( B ) denotes the speed of light in A and B . Then which of the following is trueA. `v(A) gt v(B)` and `n(A) gt n(B)`B. `v(A) gt v(B)` and `n(A) lt n(B)`C. `v(A) lt v(B)` and `n(A) gt n(B)`D. `v(A) lt v(B)` and `n(A) lt n(B)` |
| Answer» Correct Answer - b | |
| 300. |
As shown, a narrow beam of light is incident onto a semi-circular glass cylinder of radius R. Light can exit the cylinder when the beam is at the centre. When the beam is moved parallel to a maximum distance d from the central line, no light can exit the cylinder from its lower surface. Find the refractive index of the glass. A. `(R)/(d)`B. `(d)/(R)`C. `(R)/(sqrt(R^(2)-d^(2)))`D. `(sqrt(R^(2)-d^(2)))/(R)` |
| Answer» Correct Answer - A | |