Optical Instruments Questions and Answers

081 n Its stinct 88 1 5 4 6 G00087 In a compound microscope the intermediate image in normal use is 1 Virtual erect and magnified 2 Real erect and magnified 3 Real inverted and magnified 4 Virtual inverted and magnified 2 5

84 The magnifying power of the objective of a compound microscope is 7 if the magnifying power of the microscope is 35 then the magnifying power of eyepiece will be 1 245 2 5 3 28 4 42

There is a uniform but variable magnetic field B Bot k in a cylindrical region whose boundary is described by x y a The value of Here E is induced E F due to time varying M F cd A 0 A A C Boa 2a ahme of E dy is P

REFRACTION AT SPHERICAL SURFACES 55 A point object O is placed in front of a glass rod having spherical end of radius of curvature 30 cm The image formed would be Air Glass 30cm 15cm 1 30 cm left 3 1 cm to the right 2 infinity 4 18 cm to the left 62

D 9 The refractive index of glass with respect to water is If the velocity and wavelength of light 8 in water are 2 25x108 ms and 5400 A then the velocity and wavelength of light in glass are A 2 108 ms 4800 A B 1x108 ms 6075 A C 2 108 ms 6075 A D 1x108 ms 4800 4

Rays of light fall on a glass slab 1 as shown in figure If u at A is maximum and at Bit i maximum then what will happen to these rays A B A They will tilt towards A C They will not deviate B They will tilt towards B D There will be total internal reflection

031 11 Jan 2019 Shift 2 An amplitude modulated signal is plotted below mV t 10 V 8 V 100 s t 8 s th Which one of the following best describes the above signal com 1 9 sin 2 5 x 105 t sin 2nx 104 V

In the figure shown a thin parallel beam of light is incident on a plane mirror m at small angle d m is a concave mirror of focal length f After three successive reflections of this beam the x and y coordinates of the image is M 0 M X

4 Only b c and d 1 A person wishes to distinguish between two pillars located at a distance of 11 km What should be the minimum distance between these pillars 1 1 m 2 3 m 3 0 5 m 4 5 m Find the thickness of a plate which will produce a

A ray is incident on a spherical body 3 making an angle 60 with the normal drawn at the point of incidence The ray after passing through sphere gets incident on the farther surface of sphere and get reflected and refracted Then the angle between the reflected and refracted rays at this surface is 45 90 O 120 150 i 60 3 a

A ray is incident on a spherical body u 3 making an angle 60 with the normal drawn at the point of incidence The ray after passing through sphere gets incident on the farther surface of sphere and get reflected and refracted Then the angle between the reflected and refracted rays at this surface is i 60 A 45 B 90 C 120 D 150 3 a

face of a rectangular glass plate of 8 cm thickness is silvered An object held 10cm in front of the unsilvered face forms an image 12cm behind the silvered face What is the refractive index of the glass YOUR ANSWER CORRECT ANSWER IS 2 5

4 A concave lens forms the image of an object such that the distance between the object and image is 10 cm If magnification of the image is 1 The focal length of the lens is E 1 6 cm 20 2 cm 3 3 cm 1 2 orrect Bleaca mention reason from below 3 4

If a light incident normally on one of the faces of the pris m of refractive index 2 and the emergent ray just grazes th e second face of the prism find angle of deviation

A particle of mass 5 kg is moving in x y plane such that x t 2 sin 2t y t t3 4t and z t 5 If all measurements are in SI units then Total acceleration of particle at t sec is along y axis Velocity of particle at t 0 is v 41 41 O Acceleration of particle at t 0 is 81 61 Particle is under constant acceleration motion

A person with normal vision can just resolve two poles separated by a distance of 10 m If the limit of resolution be 1 minute then the distance of the poles from the person is Only one correct answer A 34 km B C D 3 4 km 68 km 6 8 km

front of a convex lens of focal length 0 5 m A plane mirror is placed at a distance of 2 m behind the lens The position and nature of the final image formed by the system is A 2 6 m from the mirror real B 1 m from the mirror real C 2 6 m from the mirror virtual D 1 m from the mirror virtual

What happened to 1 22 lambda in th e formula In ncert the formula is 2n sintheta 1 22 lambda Resolving power of compound microscope is given by symbols have their usual meaning x d 1 d de de 2 2 sin e 2u sine 1 22 D D 221

Unpolarized light with intensity I is incident on two polaroids The axis of the first polaroid makes an angle of 50 with the vertical and the axis of the second polaroid is horizontal What is the intensity of the light after it has passed through the second polaroid Ans 1 2 x cos 40027

A point source of light is kept at a distance of 15 cm from a converging lens on its optical axis The focal length of the lens is 10 cm and its diameter of aperture is 3 cm A screen is placed on the other side of the lens perpendicular to the axis of the lens at a distance 20 cm from it Find the area of the illuminated part of the screen O x T 15 cm cm cm cm 2 20 cm Screen

The magnitude of image distance of a bus as seen by the driver of an ambulance in rear view mirror of focal length 10 cm is about Assume bus is situated 10 m from the rear view mirror 10 cm GR ug af du y du dich ufafara cachi RH4 6444 414I 10 m 0 40 m 0 20 m 0 30 m 010 m

A cylindrical tube filled with water w 4 3 is closed at its both ends by two silvered plano convex lenses as shown in the figure Refractive index of lenses L and L2 are 2 0 and 1 5 while their radii of curvature are 5 cm and 9 cm respectively A point object is placed some where at a point O on the axis of cylindrical tube It is found that the object and image coincide each other E L the CO 1 42 L

A plano convex lens has a thickness of 4cm When placed on a horizontal table with the curved surface in contact with it the apparent depth of the bottom most point of the lens is found to be 3cm If the lens is inverted such that the plane face is in contact with the table the apparent depth 1984 of the centre of the plane face of the lens is found to be 25 8cm Find the focal length of the lens

An insect of negligible mass is sitting on a block of mass m tied with spring of force constant K The maximum speed of insect relative to its image when complete arrangement perform vertical oscillation of amplitude A is Vmax Choose the correct option 0000000 So 0 Vmax 0 O Vmax A 0Vmax A K 2m Minimum speed of insect image relative to insect will be zero

j 2 25 For the angle of minimum deviation of a prism to be equal to its refracting angle the prism must be made of a material whose refractive index 2012 Mains a Lies between 2 and 1 a Vies b Lies between 2 and 2 c Is less than 1 d Is greater than 2 ridwan

33 In a compound microscope the focal length of the eye piece is 5 cm and magnification is 30 If final image is formed at 25 cm then the magnification produced by the object is A 10 B 5 C 1 D 15

A concave mirror of focal length 20 cm is cut into two parts from the middle and the two parts are moved perpendicularly by a distance 1 cm from the previous principal axis AB Find the distance between the images formed by the two parts A 10cm Z lem lem B

A body cools from 60 C to 50 C in 10 minutes If the room temperature is 25 C and assuming Newton s law of cooling to hold good the temperature of the body at the end of the next 10 minutes will be 1 38 5 C 3 42 85 C 2 40 C 4 45 C

The principal axis of a spherical mirror is shown by dotted line O is the point object whose real image is Radius of curvature of spherical mirror is equal to cm w 8 10 cm cm O 20 cm O 15 cm 20 O cm 1 cm

Question No 16 A point object is placed at distance of 20 cm from a lens as shown in figure The distance of final image from the lens in cm is 10 cm Object Answer 50 f 30 cm Plane mirror 02 03 4 O 50 O 09 07 08 O G

ABC is a right angled prism having other angles of 30 and 60 as shown Two rays 1 and 2 are incident on prism such that ray 1 just suffers TIR on second face Ray 2 is incident on one face and emerges perpendicular to the other face If light incident has same wavelength choose correct options 2 B 60 Refractive index of the prism is 2 Deviation suffered by ray 2 is 60 Angle of deviation suffered by ray 2 is 30 The refractive index of the prism is 2

A point object is placed at distance of 20 cm from a lens as shown in figure The distance of final image from the lens in cm is Object Answer 08 09 10 cm f 30 cm 01 02 03 04 05 06 07 08 09 Plane mirror 1 02 03 04 05 06 07

Q 16 A charged particle mass m and charge q moves along X axis with velocity Vo When it passes through the origin it enters a region having uniform electric field E Ej which extends upto x d Equation of path of electron in the region x dis Y 1 y 3 y 0 qEd mV X Vo qEd d d gEd mV2 2 y 4 y x d 9Ed X

36 A thick plano convex lens is silvered at both surfaces A point source of light S is placed inside the lens at a distance of 2 cm from curved surface having radius of curvature shown in the figure If the images formed due to direct reflections from the plane and curved surface coincide then the thickness of the lens is 1 6 cm 2 20 3 cm 3 7 cm 4 3 cm S D TITT 8 3 cm as

A hollow double concave lens is made of very thin transparent material It can be filled with air or either of two liquids L or L having refractive indices u and 1 2 respectively 1 The lens will diverge a parallel beam of light if it is filled with IIT JEE 2000 a air and placed in air b air and immersed in L L and immersed in L2 d L and immersed in L

n the given figure rectangular box is a thin lens If the point Ois 1 cm above the axis then what is th height of the image in cm Consider the optical centre of the lens to be the origin Given that X 5 cm Ray 1 Ray 2 X 0 axis

The refractive index of the material of a prism is 2 13 and the refracting angle is 90 Calculate the angle of minimum deviation and the corresponding angle of incidence Show that the limiting angle of incidence for getting emergent ray is 45 basah birth

A cylindrical tube filled with water w 4 3 is closed at one end by silvered plano convex lens as shown in figure Refractive index of lens is 2 and radii of curvature is 5 cm A point object is placed somewhere at a point O on the axis of cylindrical tube It is found that the object and image formed by L coincide with each other Then the distance of object from lens L is k cm Then value of kis L

A thin prism with refracting angle 5 and having refractive index 1 6 is kept adjacent to another thin prism having refractive index 1 5 such that one is inverted with respect to the other An incident ray fall ing vertically on the first prism passes through the sec ond prism without any deviation Calculate the refracting angle of the second prism 2

A concave mirror of focal length 12 cm and a convex mirror of focal length 17 cm are placed facing each other 48 cm apart A point object is placed between the mirrors on their common axis 17 cm from the concave mirror The position of image formed by reflection first at the concave mirror and then at convex mirror is 1 Behind concave mirror at distance of 5 06cm Behind convex mirror at distance of 5 06 cm 3 Behind concave mirror at distance 12 8 cm 4 Behind convex mirror at distance 12 8 cm

Which one of the OH OH CI OH OH CI CI Solution Answer 1 Hint E W G increases acidic si ngth of phenol Sol Acidic strength OH OH pk 8 48 OH 6 6 6 9 02 OH CI 9 38 9 95

8 A face of a prism of refracting angle 30 silvered A ray of light is incident on the othe face at angle of incidence 45 After refectio from the silvered face the ray retraces its pat The index of refraction of prism will be 1 4 2 2 3 2 4 2

An ionized gas contains both positive and negative ions If it is subjected simultaneous electric field along the x direction and a magnetic field along the z direction then A positive ions deflect towards y direction and negative ions towards y direction B all ions deflect towards y direction C all ions deflect towards y direction D positive ions deflect towards y direction and negative ions towards y direction

An equiconvex lens of refractive index 1 5 and focal length f is held normally to the path of a parallel beam of light The lens is tilted through a small angle Then A the new focal length is f sec B the image is displaced by fo from its initial position C the focal length remains unchanged D the image is not displaced at all

An equiconvex lens of refractive index u 1 5 and focal length f is held normally to the path of a parallel beam of light The lens is tilted through a small angle Then A the new focal length is f sec o B the image is displaced by fo from its initial position C the focal length remains unchanged D the image is not displaced at all noo different radioactive materials

such that only 50 of the incident radiation absorbed Radiation pressure due to EM wave is 1 2 10 3 210 31 2C

19 A concave mirror produces four times magnified real image of an object placed at 10 cm in front of it What the focal length of mirror OR

13 A source of light of wavelength 5000 A is placed in situation as shown in figure Considering interference of direct and reflected rays Comments about the position of the region where the fringes will be visible and total the number of fringes are given as the options Choose the correct options L 1mm D Mirror C O 5cm 5cm 190cm M A the width of the region on the screen where interference pattern is visible is nearly 5 mm B the width of the region on the screen where interference pattern is visible is nearly 10 mm C Total number of fringes which are visible on the screen are nearly 40 D Total number of fringes which are visible on the screen are nearly 50

23 A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting the angle formed by the image of the tower is 0 then 0 is close to a 15 b 60 c 30 d 1 JEE Main 15 Online

34 Assertion A Higher the refractive index of the prism material lower the angle of deviation Reason R The angle of deviation is directly proportional to the angle of prism O Both Assertion A and Reason R are true and Reason R is the correct explanation of Assertion A O Both Assertion A and Reason R are true but Reason R is not the correct explanation of Assertion A O Assertion A is true but Reason R is false O Assertion A is false but Reason R is true