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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.
| 901. |
A small ink dot on a paper is viewed through a glass slab of thickness `10 cm` , and refractive index `1.5`. By what distance would the dot appear to be raised ? |
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Answer» Here, real thickness of glass slab, `x = 10 cm , mu = 1.5` If apparent thickness of glass slab is `y`, then from `mu = (x)/(y)` `y = (x)/(mu) = (10)/(1.5) = 6.67 cm` Distance through which the dot appears to be raised `= x - y = 10 - 6.67 = 3.33 cm`. |
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| 902. |
A convergent beam of light passes through a diverging lens of focal length `0.2 m` and comes to focus at a distance of `0.3 m` behind the lens. Find the position of the point at which the beam would converge in the absence of the lens.A. `0.12 m`B. `0.6 m`C. `0.3 m`D. `0.15 m` |
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Answer» Correct Answer - A Here `f = -0.2 m, v = +0.3 m` The lens formula `1/v - 1/u = 1/f rArr 1/u = 1/v - 1/f = (1)/(0.3) + (1)/(0.2) = (0.5)/(0.06)` `u = (0.06)/(0.5) = 0.12 m` |
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| 903. |
A glass slab of thickness `3cm` and refractive index `3//2` is placed on ink mark on a piece of paper. For a person looking at the mark at a distance `5.0 cm` above it, the distance of the mark will appear to beA. 3.0 cmB. 4.0 cmC. 4.5 cmD. 5.0 cm |
| Answer» Correct Answer - b | |
| 904. |
A concave lens is placed in the path of convergent rays. The rays are focussed on the axis 15 cm behind the lens. Where would these rays have been focussed in the absence of the lens ? Focal length of the lens is 30 cm. |
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Answer» Correct Answer - At a distance of 10 cm behind the lens |
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| 905. |
A microscope is focussed on an ink mark on the top of a table. If we place a glass slab of 3 cm thick on it, how should the microscope be moved to focus the ink spot again? The refractive index of glass is 1.5A. 2 cm upwardsB. 2 cm downwardsC. 1 cm upwardsD. 1 cm upwards |
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Answer» Correct Answer - C (c ) Given, n=1.5, and `h_(o)=3cm` Refractive index, `n=h_(o)/h_(i) rArr 1.5=3/h_(i)` Apparent depth , `h_(i)=3/1.5=2 cm` Hence, 3-2=1 cm upwards. |
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| 906. |
A cocave lens forms the image of an object such that the distance between the object and image is 10 cm and the magnification produced is 1/4. the focal length of the lens will beA. 8.6 cmB. 6.2 cmC. 10 cmD. 4.4 cm |
| Answer» Correct Answer - D | |
| 907. |
A parallel beam of light is incident on the system of two convex lenses of focal length `f_(1)=20cm` and `f_(2)=10cm` . What should be the distance between the two lenses so that rays after refraction from both the lenses pass undeviated? A. 60 cmB. 30 cmC. 90 cmD. 40 cm |
| Answer» Correct Answer - B | |
| 908. |
A film projector magnifies a `100 cm^(2)` film strip on a screen. If the linear magnification is 4, the area of magnified film on the screen isA. `1600 cm`B. `400 cm`C. `800 cm`D. `200 cm` |
| Answer» Correct Answer - a | |
| 909. |
When an object is placed at a distance of 25 cm from a mirror, the magnification is `m_(1)`. The object is moved 15cm farther away with respect to the earlier position, and the magnification becomes `m_(2)`. If `m_(1)//m_(2)=4` , then calculate the focal length of the mirror.A. `20cm` convexB. `20cm`, concaveC. `10cm`, convexD. `10cm` concave |
| Answer» Correct Answer - (b) | |
| 910. |
Two thin lenses of focal lengths 20cm and 25cm are placed in contact. The effective power of the combination isA. 45 dioptresB. 9 dioptresC. 1/9 dioptreD. 6 dioptres |
| Answer» Correct Answer - b | |
| 911. |
When light is incident on a medium at angle i and refracted into a second medium at an angle r, the graph of `sin r` versus `sin i` is as shown. From this one can conclude that (i) the velocity of light in second medium is `sqrt3` times the velocity of light in the first medium (ii) the velocity of light in the first medium is `sqrt3` times the velocity of ligth in second medium (iii) the critical angle of the two media is given by `sin i_C=1sqrt3` (iv) the critical anlge of the two media is given by `sin i_C=1sqrt2`A. Velocity of light in the second medium is 1.73 times the velocity of light in the I mediumB. Velocity of light in the I medium is 1.73 times the velocity in the II mediumC. The critical angle for the two media is given by `sin i_(C)=(1)/sqrt(3)`D. `sin i_(C)=1/2` |
| Answer» Correct Answer - bc | |
| 912. |
The linear magnification of a concave mirror is.A. always positiveB. always negativeC. sometimes positive and sometimes negativeD. cannot predict |
| Answer» Correct Answer - A | |
| 913. |
An object is 30.0 cm from a spherical mirror along the central axis. The absolute value of lateral magnification is `(1)/(2)`. The image produced is inverted. What is the focal length of the mirror? |
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Answer» Image is inverted, so it is real, u and v both are negative. Magnification is `(1)/(2)`,therefore,v=`(u)/(2)`. Given, u=-30cm and v=-15 cm Using the mirror formula, `(1)/(v)+(1)/(u)=(1)/(f)` we have, `(1)/(f)=(1)/(-15)-(1)/(30)=(1)/(10)` `therefore` Focal length f=-10 cm |
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| 914. |
The graph between the lateral magnification `(m)` produced by a lens and the distance of the image `(v)` is given byA. B. C. D. |
| Answer» Correct Answer - c | |
| 915. |
An object is 30.0 cm from a spherical mirror along the central axis. The absolute value of lateral magnification is `(1)/(2)`. The image produced is inverted. What is the focal length of the mirror?A. 10 cmB. `-10 cm`C. `- 15`D. 15 |
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Answer» Correct Answer - B Image is inverted so it is real, u and v both are negative. Magnification is `(1)/(2)`, therefore, `v=(u)/(2)`. Given, u = - 30 cm and v = - 15 cm Using the mirror formula, `(1)/(v)+(1)/(u)=(1)/(f)` we have, `(1)/(f)=(1)/(-15)-(1)/(30)=-(1)/(10)` `therefore` Focal length `f= -10 cm` |
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| 916. |
Which of the following graphs is the magnification of a real image against the distance from the focus of a concave mirrorr ?A. B. C. D. |
| Answer» Correct Answer - d | |
| 917. |
In a concave mirror, an object is placed at a distance `d_1` from the focus and the real image is formed aat a distance `d_2` from the focus. Then the focal length of the mirror is :A. `sqrt(d_1 d_2)`B. `d_1 d_2`C. `(d_1 + d_2)//2`D. `sqrt(d_1//d_2)` |
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Answer» Correct Answer - A Here, `u = -(f + d_1) and v = -(f + d_2)` From `(1)/(u)+(1)/(v)=(1)/(f)` `(1)/(-(f + d_1)) + (1)/(-(f + d_2)) = (1)/(-f)` `(2 f + d_1 + d_2)/((f + d_1)(f + d_2))=(1)/(f)` or `2f^2 + (d_1 + d_2)f = f^2 + d_1 f + d_2 f + d_1 d_2` `f^2 = d_1 d_2` or `f = sqrt(d_1 d_2)`. |
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| 918. |
A concave mirror is used to focus the image of a flower on a nearby well 120 cm from the flower. If a lateral magnification of 16 is desired, the distance of the flower from the mirror should beA. 8 cmB. 12 cmC. 80 cmD. 120 cm |
| Answer» Correct Answer - a | |
| 919. |
If x is the distance of an object from the focus of a concave mirror and y is the distance of image from the focus, then which of the following graphs is correct between x and yA. B. C. D. |
| Answer» Correct Answer - b | |
| 920. |
Assertions `:` A beam of white light give a spectrum on passing through a hollow prism. Reason`:` Speed of light outside the prism is different from the speed of light inside the prism.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 | |
| 921. |
Assertion : Diamond glitters brilliantly. Reason : Diamond does not absorb sunlight.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 | |
| 922. |
A beam of monochromatic blue light of wavelength 4200Å in air travels in water `(mu=4//3)`. Its wavelength in water will beA. `2800 Å`B. `5600 Å`C. `3150 Å`D. `4000 Å` |
| Answer» Correct Answer - c | |
| 923. |
The radii of curvature of each surface of a convex lens is `20 cm` and the refractive index of the material of the lens is `3//2` (i) Calculate its focal length (ii) If this is cut along the plane `AB`. What will be formed ? (iii) What happens if the lens is cut along `CD` ? |
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Answer» Correct Answer - (i) 20 cm (ii) 40 cm (iii) f remains |
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| 924. |
A bioconvex lens whose both the surface have small radii of curvature has a power of`5D`.The refractive index of material of lens is `1.5`.The radii of curvature of each surface is:- `(1)20cm ,(2)15cm, (3) 10cm ,(4) 5cm` |
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Answer» `P=(1)/(f):.f=(1)/(P)=(1)/(5)m=20cm` For an equiconvex lens `(1)/(f)=(2(mu-1))/(R )` `R=2(mu-1)f` `=2xx0.5xx20=20cm` |
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| 925. |
An object of length `1`cm is placed at a distance of`15cm`from a concave mirror of focal length`10cm`.The nature and size of the image are- (1) real,inverted,`1.0cm` ,(2)real, inverted,`2.0cm` ,(3)virtual ,erect,`0.5cm` (4) virtual ,erect,`1.0cm` |
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Answer» Given`u=-15cm,f=-10cm,O=1cm` `(1)/(v)+(1)/(u)=(1)/(f) ,=(1)/(v)=(1)/(f)-(1)/(u)=(1)/(-10)-(1)/(-15)` `:.v=-30cm (1)/(O)=-(v)/(u)=-(-30)/(-15)=-2` `l=-2xx1=-2` Image is inverted and on the same side(real)of size`2cm`. |
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| 926. |
The optical path of a monochromatic light is same if it goes through 4.0 cm of glass or 4.5 cm of water. If the refractive index of glass is 1.53, the refractive index of the water isA. `1.30`B. 1.36C. 1.42D. 1.46 |
| Answer» Correct Answer - b | |
| 927. |
The optical path of a monochromatic light is same if it goes through `4.0cm` of glass of `4.5cm` of water. If the refractive index of glas is `1.53`, the refractive index of the water isA. `1.30`B. `1.36`C. `1.42`D. `1.46` |
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Answer» (b) Optical pathh `mux=` constant i.e. `mu_(1)x_(1)=mu_(2)x_(2)implies1.53xx4=mu_(2)xx4.5` `implies mu_(2)=(1.53xx4)/4.5=1.36` |
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| 928. |
What is the apparent position of an object below a rectangular block of glass `6 cm` thick, if a layer of water `4 cm` thick is on the top of the glass ? Given `^(a)mu_(g) = 3//2 and ^(a)mu_(w) = 4//3`. |
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Answer» Here, real depth of glass, `x_(1) = 6 cm`, real depth of water, `x_(2) = 4 cm`. `.^(a)mu_(g) = 3//2, .^(a)mu_(w) = 4//3` If `y_(1),y_(2)` are the corresponding apparent depths, Then, `(x_1)/(y_1) = .^(a)mu_(g) = (3)/(2)` `:. y_(1) = (2)/(3) x_(1) = (2)/(3) xx 6 = 4 cm` `(x_2)/(y_2) = .^(a)mu_(w) = (4)/(3)` `:. y_2 = (3)/(4) x_2 = (3)/(4) xx 4 = 3cm` Apparent position of the object =`(y_1 + y_2) = (4 + 3) cm = 7 cm` `:.` Rise in position of the object =`(x_1 + x_2)-(y_1 + y_2) = (6 + 4) - (4 + 3)` =`10 - 7 = 3 cm`. |
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| 929. |
An experment is performed to find the refractive index of glass using a travelling mircroscope. In this experiment distances are measured byA. a screw gauge provide on the microscopeB. a vernier scale provided on the microscopeC. a standard laboratory scaleD. a metre scale provided on the microscope |
| Answer» Correct Answer - 3 | |
| 930. |
In case of spherical mirrors, all distances are measured from………. . |
| Answer» Correct Answer - pole of the mirror | |
| 931. |
Assertion : A convex mirror is preferred over a plane mirror in vehicles to observer traffic coming from behind. Reason : Images formed by convex mirrors are erect and diminished in size.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 A convex mirror produces smaller images which increase the field of view as compared to a plane mirror of same size. Also in case of convex mirro the image is erect like in plane mirror. |
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| 932. |
An object is moving towards a stationary plane mirror wiyh a speed of 2 m/s. Velocity of the image w.r.t. the object isA. 2 m/s towards rightB. 4 m/s towards rightC. 2 m/s towards leftD. 4 m/s towards left |
| Answer» Correct Answer - D | |
| 933. |
A ray of light is incident on a plane mirror at an angle of incidence of `30^@`. The deviation produced by the mirror isA. `30^(@)`B. `60^(@)`C. `90^(@)`D. `120^(@)` |
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Answer» Correct Answer - D (d) Deviation by a plane mirror, `delta=180^(@)-2theta=180^(@)-60^(@)=120^(@)` |
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| 934. |
A plane mirror produces a magnification ofA. `-1`B. `+1`C. ZeroD. Between 0 ans `+oo` |
| Answer» Correct Answer - b | |
| 935. |
If the reflected ray is rotated by an angle of `4theta` in clockwisse direction then the mirror was rotated byA. `2theta` in anti-clockwise directionB. `4theta` in anti-clockwise directionC. `2theta` in clockwise directionD. `4theta` in clockwise direction |
| Answer» Correct Answer - A | |
| 936. |
When a plane mirror is rotated through an angle ` theta` then the reflected ray turns through the angle `2 theta` then the size of the imageA. Is doubledB. Is halvedC. Remins the sameD. Becomes infinite |
| Answer» Correct Answer - c | |
| 937. |
The length of the compound microscope is `14 cm.` The magnifying power for relaxed eye is `25`. If the focal length of eye lens is `5 cm`, then the object distance for objective lens will beA. 1.8 cmB. 1.5 cmC. 2.1 cmD. 2.4 cm |
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Answer» Correct Answer - A Length of compound microscope, `L_(oo)=v_(o)+f_(e )rArr 14 v_(o)+5` `therefore " " v_(o)=9 cm` Mgnifying power of microscope for relaxed eye `M=(v_(o))/(u_(o)).(D)/(f_(e ))` or `25=(9)/(u_(o)).(25)/(5)` or distant of object, `u_(o)=(9)/(5)=1.8 cm` |
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| 938. |
If the focal length of objective and eye lens are `1.2 cm` and `3 cm` respectively and the object is put `1.25cm` away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope isA. 150B. 200C. 250D. 400 |
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Answer» Correct Answer - B When final image is formed at infinity, then magnifying power `M_(oo)=-(v_(o))/(u_(o))xx(D)/(f_(e ))` From, `(1)/(f_(o))=(1)/(v_(o))-(1)/(u_(o))` `(1)/(+1.2)=(1)/(v_(o))-(1)/((-1.25))` `rArr " " v_(o)=30 cm` `therefore " " |M_(oo)|=(30)/(1.35)xx(25)/(3)=200` |
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| 939. |
The focal length of plano-convex lens, the convex surface of which is silvered is `0.3m`, if `mu` of the lens is `7//4`, the radius of curvature of the convex surface isA. `0.45m`B. `1.05m`C. `3m`D. `0.9m` |
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Answer» (b) Here `P=2P_(L)+P_(M)=2/(f_(L))-1/(f_(m))` `P=2/(f_(L))+2/R` Here `1/(f_(L))=(mu-1)(1/(r_(1))-1/r_(2)))=(7/4-1)(1/(oo)+1/R)` `1/(f_(L))=3/(4R)` `:. P=-1/F=6/(4R)+2/R+(6+8)/(4R)=14/(4R)` or `-10.3=14/(4R)` `:. R=_(14xx0.3)/4=-4.2/4=-1.05` |
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| 940. |
A compound microscope is made using a lens of focal `10 mm` as objective and another lens of focal length `15 mm` as eye piece. An object is held `1.1 cm` from the objective and final image is obtained at `oo`. Calculate distance between objective and eye piece. |
| Answer» Correct Answer - `12.5 cm` | |
| 941. |
A person with a normal near point `(25 cm)` using a compound microscope with an objective of focal length `8.0 mm` and eye piece of focal length `2.5 cm` can bring an object placed `9.0 cm` from the objective in sharp focus. What is the separation between the two lenses ? Calculate the magnifying power of the microscope ? |
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Answer» Here, `d = 25 cm, f_0 = 8.0 mm = 0.8 cm, f_e = 2.5 cm, u_0 = -9.0 mm = -0.9 cm` As `(1)/(v_e)-(1)/(u_e)=(1)/(f_e) :. (1)/(u_e)=(1)/(v_e)-(1)/(f_e)` `(v_e = - d = -25 cm)` =`(1)/(-25) - (1)/(2.5) = (-1 - 10)/(25) = -(11)/(25)` `u_e = -(25)/(11) = -2.27 cm` Again `(1)/(v_0)-(1)/(u_0) = (1)/(f_0)` `(1)/(v_0)=(1)/(f_0)+(1)/(u_0)=(1)/(0.8)+(1)/(-0.9)=(0.9 - 0.8)/(0.72) = (0.1)/(0.72)` `v_0 = (0.72)/(0.1) = 7.2 cm` `:.` Separation between the two lenses `=|u_e|+ v_0 = 2.27 + 7.2 = 9.47 cm` Magnifying power `= (v_0)/(|u_0|)(1 + (d)/(f_e)) = (7.2)/(0.9)(1 + (25)/(2.5)) = 88`. |
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| 942. |
A prism of refractive index `m` and angle `A` is placed in the minimum deviation position. If the angle of minimum deviation is `A`, then the value of `A` in terms of `m` isA. `sin^(-1) ((mu)/(2))`B. `sin^(-1) sqrt((mu - 1)/(2))`C. `2 cos^(-1) ((mu)/(2))`D. `cos^(-1) ((mu)/(2))` |
| Answer» Correct Answer - c | |
| 943. |
Which one of the following alternative is FALSE for a prism placed in a position of minimum deviationA. `i_(1) = i_(2)`B. `r_(1) = r_(2)`C. `i_(1) = r_(1)`D. All of these |
| Answer» Correct Answer - c | |
| 944. |
Three prisms 1, 2 and 3 have the prism angle `A = 60^(@)`, but their refractive indices are respectively 1.4, 1.5 and 1.6. If `delta_(1), delta_(2), delta_(3)` be their respective angles of deviation thenA. `delta_(3) gt delta_(2) gt delta_(1)`B. `delta_(1) gt delta_(2) gt delta_(3)`C. `delta_(1) = delta_(2) = delta_(3)`D. `delta_(2) gt delta_(1) gt delta_(3)` |
| Answer» Correct Answer - a | |
| 945. |
The velocity of light in glass is `2 xx 10^(8)ms^(-1)` while that in vaccum is `3 xx 10^(8)ms^(-1)`. By how much would an ink dot appeat to be raised when covered by a glass plate of 4.5 cm thickness. |
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Answer» Correct Answer - 1.5 cm |
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| 946. |
Two lamps of luminous intensity of 8 Cd and 32 Cd respectively are lying at a distance of 1.2 m from each other. Where should a screen be placed between two lamps such that its two faces are equally illuminated due to two sourcesA. 10 cm from 8 Cd lampB. 10 cm from 32 Cd lampC. 40 cm from 8 Cd lampD. 40 cm from 32 Cd lamp |
| Answer» Correct Answer - c | |
| 947. |
A compound microscope has two lenses. The magnifying power of one is 5 and the combined magnifying power is 100. The magnifying power of the other lens isA. 10B. 20C. 50D. 25 |
| Answer» Correct Answer - b | |
| 948. |
When white light passes through a glass prism one gets spectrum on the other side of the prism in the emergent beam the ray which is deviating least is or Deviation by a prism is lowest forA. Violet rayB. Green rayC. Red rayD. Yellow ray |
| Answer» Correct Answer - c | |
| 949. |
We use flint glass prism to disperse polychromatic light because light of different coloursA. Travel with same speedB. Travel with same speed but deviate differently due to the shape of the prismC. Have different anisotropic properties while through the prismD. Travel with different speeds |
| Answer» Correct Answer - c | |
| 950. |
Fraunhofer lines are obtained inA. Solar spectrumB. The spectrum obtained from neon lampC. Spectrum from a discharge tubeD. None of the above |
| Answer» Correct Answer - a | |