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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.
| 551. |
In the following diagram are shown the position of an object O, image I and two lenses. The focal length of one lens is also given. Determine the focal length of the other lens. |
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Answer» Correct Answer - 12.63 cm |
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| 552. |
In the following ray diagram are given the position of an object O, image I and two lenses `L_(1)` and `L_(2)`. The focal length of `L_(1)` is also given. Find the focal length of `L_(2)`. |
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Answer» Correct Answer - 20 cm |
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| 553. |
In the diagram shows below rays are coming from infinity and after passing through both the lenses meet on a screen placed at a distance of 30 cm from the concave lens. Calculate the focal length of the concave lens. |
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Answer» Correct Answer - 15 cm |
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| 554. |
When a slide is placed 15 cm behind the lens in a projector, an image is formed at 3 infront of the lens. (i) Show the image formation by a ray diagram. (ii) Find the focal length of the lens. (iii) What will be the distance between the lens and the slide in order to get and image at a distance 4 metre from the lens ? (iv) Determine the magnification for the case (iii). |
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Answer» Correct Answer - (ii) `+14.3cm` (ii) `-14.8cm` (iv) `-27` |
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| 555. |
If there had been one eye of the man, thenA. image of the object would have been invertedB. visible region would have decreasedC. image would have not been seen three-dimensionalD. Both (b) and (c ) |
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Answer» Correct Answer - D (d) If there had been one eye of the man, then visible region decreases, so the depth of the iimage will not be seen. |
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| 556. |
If there had been one eye of the man, thenA. Image of the object would have been invertedB. Visible region would have decreasedC. Image would have not been seen three dimensionalD. (b) and (c) both |
| Answer» Correct Answer - d | |
| 557. |
How should people wearing spectacles work with a microscopeA. They cannot use the microscope at allB. They should keep on wearing their spectaclesC. They should take off spectaclesD. (b) and (c) is both way |
| Answer» Correct Answer - c | |
| 558. |
A person cannot see the objects distinctly, when placed at a distance less than `100 cm`. What is the power of the spectacles that he should use to see clearly the objects placed at `25 cm` ?A. `+ 3.0 D`B. `+ 0.125 D`C. `- 3.0 D`D. `+ 4.0 D` |
| Answer» Correct Answer - a | |
| 559. |
The resolving power of a telescope depends onA. Focal length of eye lensB. Focal length of objective lensC. Length of the telescopeD. Diameter of the objective lens |
| Answer» Correct Answer - d | |
| 560. |
The ratio of the speed of an object to the speed of its real image of magnification `m` in the case of a convex mirror is.A. `- (1)/(m^2)`B. `m^2`C. `- m`D. `(1)/(m)` |
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Answer» Correct Answer - A As `(1)/(v)+(1)/(u)=(1)/(f)` Differentiating w.r.t.t, we get `:. (-1)/(v^2) (d v)/(dt)-(1)/(u^2) (du)/(dt) = 0` or `(du//dt)/(dv//dt) = - (u^2)/(v^2) = -(1)/(m^2)` `(because m = (v)/(u))`. |
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| 561. |
A telescope using light having wavelength 5000 Å and using lenses of focal lengths 2.5 cm and 30 cm. If the diameter of the aperature of the objective is 10 cm, then the resolving limit of telescope isA. `6.1xx10^(-6)`radB. `5.0xx10^(-6)`radC. `8.3xx10^(-4)`radD. `7.3xx10^(-3)`rad |
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Answer» Correct Answer - A (d) Resolving limit of telescope `(1.22lamda)/a=(1.22xx(500xx10^(-10)))/0.1=6.1xx10^(-6) rad` |
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| 562. |
If the aperature of a telescope is decreased resolving power willA. increasesB. decreasesC. remain sameD. zero |
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Answer» Correct Answer - B (b) the resolving power of telescope = `a/(1.22lamda)` where, a= aperature of telescope `therefore` Resolving power `prop` aperature of telescope If aperature of telescope is decreased, then the resolving power will decrease. |
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| 563. |
The focal length of a convex lens is 10 cm and its refractive index is 1.5. If the radius of curvature of one surface is 7.5 cm , the radius of curvature of the second surface will beA. 7.5 cmB. 15.0 cmC. 75 cmD. 5.0 cm |
| Answer» Correct Answer - b | |
| 564. |
A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination isA. `- 1.5 D`B. `- 6.5 D`C. `+ 6.5 D`D. `+1.5 D` |
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Answer» Correct Answer - A Focal length of the combination, `(1)/(F)=(1)/(f_(1))+(1)/(f_(2))` `rArr " " (1)/(F)=(1)/((+40))+(1)/((-25))` `rArr " " F=-(200)/(3)cm` As, Power, `P=(100)/(F)=(100)/((-200//3))=-1.5 D` |
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| 565. |
A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination isA. `-1.25D`B. `-6.5D`C. `+6.5D`D. `+1.25D` |
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Answer» Correct Answer - A (a) Focal length of the combination, `1/F==1/(f_(1))+1/(f_(2))` `rArr1/F=1/(+40)+1/(-25)` `rArrF=-200/3cm` As, Power,P`=100/F=100/((-200//3))=1.5D` |
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| 566. |
A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are joined together. The power of the combination will beA. `-16 D`B. `+ 16 D`C. `- 6 D`D. `+ 6 D` |
| Answer» Correct Answer - c | |
| 567. |
The combination of a convex lens ( f = 18 cm ) and a thin concave lens ( f = 9 cm ) isA. A concave lens ( f = 18 cm )B. A convex lens ( f = 18 cm )C. A convex lens ( f = 6 cm )D. A concave lens ( f = 6 cm ) |
| Answer» Correct Answer - a | |
| 568. |
An object has image thrice of its original size when kept at `8 cm` and `16 cm` from a convex lens. Focal length of the lens isA. 8 cmB. 16 cmC. Between 8 cm and 16 cmD. Less than 8 cm |
| Answer» Correct Answer - c | |
| 569. |
A convex lens has a focal length `f`. It is cut into two parts along the dotted line as shown in figure. The focal length of each part will be A. `f/2`B. `f`C. `3/2 f`D. `2 f` |
| Answer» Correct Answer - d | |
| 570. |
The angle of minimum deviation measured with a prism is `30^(@)` and the angle of prism is `60^(@)`. The refractive index of prism material isA. `sqrt2`B. 1.5C. `4/3`D. `5/4` |
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Answer» Correct Answer - A (a) Refractive index of the liquid,`mu`=`(sin((A+delta_(m))/2))/sin(A/2)=sqrt2` |
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| 571. |
A convex lens has a focal length `f`. It is cut into two parts along the dotted line as shown in figure. The focal length of each part will be A. f/2B. fC. (3/2)fD. 2f |
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Answer» Correct Answer - D (d) The focal length of each part will be 2f. |
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| 572. |
When a ray is refracted from one medium into another, the wavelegths changes from `6000Å` to `4000Å`. The critical angle for a ray from the second medium will beA. `cos^(-1)(2/3)`B. `sin^(-1)(2/sqrt3)`C. `sin^(-1)(2/sqrt3)`D. `cos^(-1)(2/sqrt3)` |
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Answer» Correct Answer - C (c ) As `""_(1)mu_(2)=1/sinC` `rArr mu_(2)/mu_(1)=lamda_(1)/lamda_(2)=1/sinC` `rArr 6000/4000=1/sin C` `rArr` Criticle angle, `C=sin^(-1)(2/3)` |
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| 573. |
If in a plano-convex lens, the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm , then the refractive index of the material of lens will beA. 20.5 cmB. 10 cmC. 15.5 cmD. 5 cm |
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Answer» Correct Answer - B (b) Focal length,F=`R/(2(µ-1))` `rArrF=10/(2(15-1))=10cm` |
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| 574. |
If in a plano-convex lens, the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm , then the refractive index of the material of lens will beA. 1.5B. 1.66C. 1.33D. 3 |
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Answer» Correct Answer - C (c ) we have, `1/f=(mu-1)(1/R_(1)-1/R_(2))` `1/30=(mu-1)(1/10)` The refractive index of the material of the lens `mu=4/3=1.33` |
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| 575. |
A beam of light is converging towards a point `I` on a screen. A plane glass plate whose thickness in the direction of the beam `=t` , refractive index `=mu` , is introduced in the path of the beam. The convergence point is shifted byA. `t(1-1/mu)` awayB. `t(1+1/mu)` awayC. `t(1-1/mu)` nearerD. `t(1+1/mu)` nearer |
| Answer» Correct Answer - a | |
| 576. |
Power `(P)` of a lens is given by reciprocal of focal length `(f)` of the lens. i.e. `P = 1//f`. When `f` is in metre, `P` is in dioptre. For a convex lens, power is positive and for a concave lens, power is negative. When a number of thin lenses of powers `p_(1), p_(2), p_(3)....` are held in contact with one another, the power of the combination is given by algebraic sum of the powers of all the lenses i.e., `P = p_(1) + p_(2) + p_(3) + ........` Answer the following questions : Focal length of the combined three lenses would beA. `-3.75 D`B. `0.5 D`C. `- 5 D`D. `1.25 D` |
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Answer» Correct Answer - A `P_2 = P - P_1 = (100)/(F) - (100)/(f_1)` `:. P_2 = (100)/(80)-(100)/(20) = 1.25 - 5 = -3.75 D`. |
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| 577. |
Power `(P)` of a lens is given by reciprocal of focal length `(f)` of the lens. i.e. `P = 1//f`. When `f` is in metre, `P` is in dioptre. For a convex lens, power is positive and for a concave lens, power is negative. When a number of thin lenses of powers `p_(1), p_(2), p_(3)....` are held in contact with one another, the power of the combination is given by algebraic sum of the powers of all the lenses i.e., `P = p_(1) + p_(2) + p_(3) + ........` Answer the following questions : Focal length of the combined three lenses would beA. `-26.7 cm`B. 60 cmC. 80 cmD. 20 cm |
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Answer» Correct Answer - A Here, `f_1 = 20 cm. f_2 = ? F = 80 cm` As `(1)/(f_1)+(1)/(f_2)=(1)/(F)` `:. (1)/(f_2) = (1)/(F)-(1)/(f_1)=(1)/(80)-(1)/(20)= -(3)/(80)` `f_2 = -(80)/(3) = -26.7 cm`. |
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| 578. |
If the focal length of the objective lens and the eye lens are 4 mm and 25 mm respectively in a compound microscope. The length of the tube is 16 cm . Find its magnifying power for relaxed eye positionA. 32.75B. 327.5C. 0.3275D. None of the above |
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Answer» Correct Answer - B |
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| 579. |
If the focal length of the objective lens and the eye lens are 4 mm and 25 mm respectively in a compound microscope. The length of the tube is 16 cm . Find its magnifying power for relaxed eye positionA. 32.75B. 327.5C. 0.3275D. None of these |
| Answer» Correct Answer - b | |
| 580. |
In a compound microscope, the distance between objective lens and eye lens is.A. fixedB. variableC. infiniteD. 1 metre |
| Answer» Correct Answer - A | |
| 581. |
For a total magnification of `175` from a compound microscope, the magnification produced by objective is `7`. What should be the magnification produced by eye piece ?A. 7B. 25C. `175 xx 7`D. none of these |
| Answer» Correct Answer - B | |
| 582. |
A man is running away from a plane mirror at the speed of `5 ms^(-1)`. With what speed is he receding from his own image ? |
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Answer» Correct Answer - `10 ms^(-1)` |
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| 583. |
A plane mirror rotating at an angular velocity of 3 radian/s reflects a light beam. The angular velocity of the reflected beam is - |
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Answer» Correct Answer - `6 rad s^(-1)` |
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| 584. |
rays of light strike a horizontal plane mirror at an angle of `45^(@)`. At what angle should be a second plane mirror be placed in order that the reflected ray finally be reflected horizontally from the second mirror. |
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Answer» Correct Answer - Second mirror should be inclined to the horizontal at angle of `67.5^(@)` |
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| 585. |
Two plane mirrors are inclined at angle `theta` as shown in figure. If a ray parallel to OB strikes the other mirror at P and finally emerges parallel to OA after two reflections then `theta` is equal to |
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Answer» Correct Answer - `theta = 60^(@)` |
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| 586. |
An object is placed at `0.06` m from a convex lens of focal length `0.1`m. Calculate the position of the image? |
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Answer» Correct Answer - 10 cm behind the mirror |
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| 587. |
Rays of light are falling on a convex lens of focal length `40 cm`. As shown in Fig. Determine the position of the image. . |
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Answer» Correct Answer - 8 cm `f = + 40 cm, u = + 10 cm, v = ?` `(1)/(v)=(1)/(f)+(1)/(u)=(1)/(40)+(1)/(10)=(5)/(40)=(1)/(8)` `v = 8 cm`. |
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| 588. |
When size of scatterer (x) is very much less than the wavelength `(lamda)` of light, intensity of scattered light `(I_s)` varies as : |
| Answer» inversely , fourth power. | |
| 589. |
What happens when sixe of scatterer is much bigger than the wavelength of light ? |
| Answer» When size of scatterer is much bigger than wavelength of light. Rayleigh scattering is not valid. In that case, all wavelength/colours are scattered equally. | |
| 590. |
When size of scatterer (x) is very much less than the wavelength `(lamda)` of light, intensity of scattered light `(I_s)` varies as :A. `I_s prop (1)/(lamda)`B. `I_s prop (1)/(lamda^2)`C. `I_s prop (1)/(lambda^4)`D. `I_s prop (1)/(lamda^6)` |
| Answer» Correct Answer - C | |
| 591. |
The relation between angle of incidence `i`, angle of prism `A` and angle of minimum deviation for a triangular prism is.A. `i = A + delta_m`B. `i= (A + delta_m)/(2)`C. `delta_m = i+ A`D. `delta_m= i- A` |
| Answer» Correct Answer - B | |
| 592. |
The deviation `delta` of a ray on passing through a prism of small angle `A` is.A. `(mu - 1)/(A)`B. `(A)/(mu - 1)`C. `(mu - 1) A`D. none of these |
| Answer» Correct Answer - C | |
| 593. |
Which of the following waves have the maximum wavelength?A. redB. violetC. yellowD. green |
| Answer» Correct Answer - A | |
| 594. |
In glass, the velocity of light is minimum for.A. redB. violetC. yellowD. green |
| Answer» Correct Answer - B | |
| 595. |
In vacuum, which colour travels fastest ?A. redB. violetC. yellowD. all colours have the same velocity. |
| Answer» Correct Answer - D | |
| 596. |
A cut diamond sparkles because of itsA. HardnessB. High refractive indexC. Emission of light by the diamondD. Absorption of light by the diamond |
| Answer» Correct Answer - d | |
| 597. |
A cut diamond sparkles because of itsA. HardnessB. High refractive indexC. Emission of light by the diamondD. Absorption of light by the diamond |
| Answer» Correct Answer - d | |
| 598. |
A beaker contains water up to a height `h_1 ` and K oil above water up to another height `h_2.` Find the apparent shift in the position of the bottom of the beaker when viewed from above. Refractive index of water is `mu_1` and that of K.oil is mu_2`.A. `(1+(1)/(mu_(1)))h_(1)-(1+(1)/(mu_(2)))h_(2)`B. `(1-(1)/(mu_(1)))h_(1)+(1-(1)/(mu_(2)))h_(2)`C. `(1+(1)/(mu_(1)))h_(2)-(1+(1)/(mu_(2)))h_(1)`D. `(1-(1)/(mu_(1)))h_(2)+(1-(1)/(mu_(2)))h_(1)` |
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Answer» Correct Answer - 4 Total shift =shift in water +shift in kerosene `=(1-(1)/(mu_(1)))h_(1)+(1-(1)/(mu_(2))) h_(2)` |
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| 599. |
Deviation of `5^(@)` is observed from a prism whose angle is small and whose refractive index is 1.5 The angle of prism isA. `7.5^(@)`B. `10^(@)`C. `5^(@)`D. `3.3^(@)` |
| Answer» Correct Answer - b | |
| 600. |
In dispersion without deviationA. The emergent rays of all the colours are parallel to the incident rayB. Yellow coloured ray is parallel to the incident rayC. Only red coloured ray is parallel to the incident rayD. All the rays are parallel, but not parallel to the incident ray |
| Answer» Correct Answer - b | |