PHY,PART TEST-1

8/9/2019 PHY,PART TEST-1

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SARTHAK CLASSES,PART TEST-1,

OPTICS,SENIORS,PHY

1. A concave mirror is placed on a horizontal table with its axis directed vertically upward.Let (0) be the pole of the mirror and C its centre of curvature. A point obect is placed at

C. !t has a real ima"e also located at C. !f the mirror is now filled with water# the ima"e willbe(A) real and will remain at C .($) real and located at a point between C and .(C) virtual and located at a point between C and %.(&) real and located at a point between C

'.A diver"in" beam of li"ht from a point source havin" diver"encean"le a falls symmetrically on a "lass slab as shown. he an"les ofincidence of the two extreme rays are e*ual . !f the thic+ness of the"lass slab is t and the refractive index n# then the diver"ence an"le ofthe emer"ent beam is

(a) ,-% ($) a (C)1

sinn

(d)1 12sin

n

-

/.A point source of li"ht $ is placed at a distance L in front of the centre

of a mirror of width d hun" vertically on a wall. A man wal+s in front ofthe mirror alon" a line parallel to the mirror at a distance 'L from it asshown. he "reatest distance over which he can see the ima"e of theli"ht source in the mirror is

(A)2

d($) d (C) 'd (&) /&

. Abeam of white li"ht is incident on a hollow prism of "lass.hen(A) the li"ht emer"in" from prism "ives no spectrum.

($) the li"ht emer"in" from prism "ives spectrum but the bendin"of all colours isaway from base.(C) the li"ht emer"in" from prism "ives spectrum# all the coloursbend towards base# the violet most and red the least.(&) the2 li"ht emer"in"# from prism "ives spectrum# all the coloursbend towardsbase# the violet the least and red the most.

. A ray of li"ht falls on the surface of a spherical paper wei"ht ma+in" an an"le a with the

normal and is refracted in the medium at an an"le b . he an"le of deviation of theemer"ent ray from the direction of the incident ray is

(A) ( )a b- ($)' ( )a b- (C)( )

2

a b-(&) ( )b a-


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3. A spherical surface of radius of curvature 4 separates air (refractive index 1.0) from "lass(refractive index 1.). he centre of curvature is in the "lass. A point 5 placed in air is foundto have a real ima"e 6 in the "lass. he line 56 cuts the surface at point 0 and 5% 7 %6 .he distance 5% is e*ual to

(A) ($) / (C) ' (&) l.8. A concave lens of "lass# refractive index 1.#has both surfaces of same radius of curvature. %n immersion in a medium of refractive index 1.8# it will behave as a

(A) Conver"ent lens of focal len"th /.($) conver"ent lens of focal len"th /.0(C) &iver"ent lens of focal len"th /.(&) diver"ent lens of focal len"th /.0

9. A point obect 0 is placed on the principal axis of a convex lens of focal len"th '0 cm at adistance of 0 cm to the left of it. he diameter of the lens is 10 cm. !f the eye is placed 30cm to the ri"ht of the lens at a distance !t below the principal axis# then the maximum value ofh to see the ima"e will be

(A) 0 cm ($) cm (C) '. cm (&) 10 cm

:. ;i"ure represents a conver"ent lens placed inside a cell filed with ali*uid. he lens has a focal len"th


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(a) (1#1) m (b) ('#1)m (c) (/#1) m (d) (#1)m

1/. he ray finally emer"es(A) parallel to the incident ray($) perpendicular to the incident ray(C) at an an"le of /0@ to the incident ray(&) at an an"le of @ to the incident ray

1. he oun"s double4slit experiment is carried '8. out with li"ht of wavelen"th 000 A. hedistance between the slits is 0.' mm and the screen is at '00 cm from the slits. he centralmaximum is at x 7 0 . he third maximum will be at x e*ual to

(a) 1.38cm (b) 1. cm (c) 0. cm (d) .0 cm

1. wo waves ori"inatin" from sources B1and s'havin" zero phase difference and commonwavelen"th will show completely destructive interference a t a point 5 if B15 B'5 is

(a) (b)3

4

(c) ' (d)11

2

13. !n an interference pattern produced by two identical slits# the intensity at the site of thecentral maximum is 1. he intensity at the same spot when either of two slits is closed is

(a)1

2(b)

I

4(c)

I

2 2(d)

I

2

18. !n oun"s experiment# usin" red and blue li"hts of wavelen"ths 8900 A and '00 Arespectively# the value of 11 for which nth red frin"e coincides with (n < 1) th blue frin"e is

(A) ' ($) / (C) (&)

19. Dhite li"ht is used to illuminate the two slits in a oun"s double4slit experiment. heseparation between the slits is b and the screen is at a distance d( b) from the slits. At apoint on the screen directly in front of one of the slits# certain wavelen"ths are missin". Bomeof these missin" wavelen"ths are

1:. !nterference frin"es were produced in oun"s double4slit experiment usin" li"ht ofwavelen"th 000 A . Dhen a film of thic+ness '. x 10 4/cm was placed in front of one of theslits# the frin"e pattern shifted by a distance e*ual to '0 frin"e4width. he refractive index

of the material of the film is(A) 1.' ($) 1./ (C) 1. (&) 1.

'0. A thin air film between a plane "lass plate and a convex lens is irradiated with parallelbeam of monochromatic li"ht and is observed under a microscope. De see(A) uniform bri"htness($) complete dar+ness(C) field crossed over by concentric bri"ht and dar+ rin"s(&) field crossed over by strai"ht bri"ht and dar+ frin"es

'1. wo slits separated by a distance of 1 mm are illuminated with li"ht of wavelen"th 3 x 1048 m . he interference frin"es are observed on a screen placed 1 m from the slits.he distance between the second dar+ frin"e and. the fourth bri"ht frin"e is e*ual to

(A) 0. mm ($) 1.0 mm (C) 1. mm (&)8.0 mm


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''. !n oun"s experiment usin" monochromatic li"ht# the frin"e pattern shifts by a certaindistance on the screen when a mica sheet of refractive index 1.3 and thic+ness 1.:3 micronis introduced in the path of one of the interferin" waves. he mica sheet is then removed andthe distance between the slitsand the screen is doubled. !t is found that the distance between successive maxima now isthe same as the observed frin"e shift upon the introduction of the mica sheet. hewavelen"th of li"ht is

(A) 83' A (b) 9'A (C) 9:'A (&)300A

'/. A beam of unpolarized li"ht. of intensity ! is passed first throu"h a to tourmaline. crystal Aand then throu"h another tourmaline crystal $ oriented so that its principal plane is parallel tothat of A. !f A is now rotated by @ in a plane perpendicular to the direction of the incidentray# intensity of the emer"ent li"ht will be

(A)2

I($)

2

I(C) ! (&)

1

4

'. A thin sheet of "lass (refractive index 1.) of thic+ness 3 micron# introduced in the pathof one of the interferin" beams in a double4slit experiment# shifts the central frin"e to a

position #earlier occupied by the fifth bri"ht frin"e. he wavelen"th of li"ht used is(A) /000 A ($) 3000 A (C) 00 A (&) 8000 A

'. !n oun"s double4slit experiment# the intensity of li"ht at a point on the screen where thepath difference is is !# bein" the

wavelen"th of li"ht used. he intensity at a point where the path difference is4

will be

(A)4

I($)

2

I(C) ! (&) ,-%

'. A clear sheet of polaroid is. placed on the top of similar sheet so that their axes ma+e an

an"le sin413

5

with each other. h' ratio of

intensity of the emer"ent li"ht to that of unpolarised incident li"ht is(A) 132' ($) :2' (C) 2 (&) 92'

'3. !n oun"s double4slit experiment# we "et 30 frin"es in the field of view if we use li"ht ofwavelen"th 000 A .he number of frin"es wewill "et in the same field of view if we use li"ht of wavelen"th 3000 A is

(A) 0 ($) :0 (C) 30 (&) 0

'8. =onochromatic li"ht of wavelen"th 000 A illuminates a pair of slits 1 mm apart. heseparation of bri"ht frin"es in the interference pattern formed on a screen ' m away is

(A) 0.' mm ($) 0.1 mm (C) 0.01 mm (&) 1.0 mm

'9. !n the double4slit experiment# the distance of the second dar+ frin"e from the central lineis / mm. he distance of the fourth bri"ht frin"e from the central line is

(A) 3mrn ($) 9 mm (C) 1' mm (&) 13 mm

':. Air has refractive index 1.000/. he thic+ness of an air column# which will have one morewavelen"th of yellow li"ht (3000 A ) than in the same thic+ness of vacuum is

(A) 'mm ($) 'cm (C) ' m (&) ' +m

/0. Aperture of the human eye is ' mm. Assumin" the mean wavelen"th of li"ht to be 000 A# the an"ular resolution limit of the eye is nearly

(A) ' minute ($) 1 minute (C) 0. minute (&) 1. minute

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PHY,PART TEST-1