Wave optics abhilash sharma notes unacadamy atoms

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1. WAVE OPTICS

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9. Amount of light

10. Points in Sam E

phase

11. Oz

13. A parallel beam of light strikes a piece of transparent glass

having cross section as shown in the figure below. Correct

Shape of the emergent wavefront will be (figures are

schematic and not drawn to scale) [Adv 2020]
Light Glass

Ol of (0) © | @

15. Q Interference of Waves;

d= PATES) E SONATE
Ya = Pa Sin (ert 8)
S >phase Difforene
AxSpath Diem À
A =A Cohenat No

25; Deg
hea (kata). WE) Sor Tb we |
Ft kan) vase

SES

|
"Er =f Le à

E

16. r WUMATION ES |
= +4 a 'CAAUUMAVONA COM

= AiSin(en- wt)+ A2Sin(en-wlrg

Sur | Min Cos$2-
Box kn urn (angi)

ax- CENTS

17. Q Interference of Waves; .

Two sources S1 and S2 emitting light of wavelength 600 nm are placed a distance 1.0 x 10-2 cm
apart. A detector can be moved on the line S1P which is perpendicular to S1S2. Locate the
position of the farthest minimum detected

(ay1.7 cm (b) 2.7 cm (c) 3.2 cm (d) 4.8 1
o A ITS
An à), Les
SP-SP aay, sO
Vag 4
UN Em D = No = mi,
nen we À, =
a= (Diy, y %

de y,

19. _ _S,P Twocoherent sources of sound, 5; and S,, produce sound
¿SPP Rene same wavelength, A= 1 m, in phase. S, and S,
are placed 1.5 m apart (see fig). A listener, located at I”

Dx = d- 2 directly in front of S, finds that the intensityisat a minimum
when he is 2 m away from S,. The listener moves away

= d-2 from S,, keeping his distance from S, fixed, The adjacent
maximum of intensity is observed when the listener is at a

l= d- 2 distance d from S,. Then, dis: [Main Sep. 05, 2020 (11)]

om 0% 0m ham

20. os as
ja T = = Lip *
be ta
Em)
Ct= Lía) =

Chu Lun) = E

Two light waves having the same wavelength A in vacuum
are in phase initially. Then the first wave travels a path L,

through a medium of refractive index n, while the second
wave travels a path of length Z, through a medium of
refractive index »,. After this the phase difference between

the two waves is : [Main Sep. 03, 2020 (11)]
(lo h (LL
Oy (2 4) OF e =)

2
9 Emo) (0) Eh)

“Aa
2H — Ml-nL,

S =Kkx= Ir
A

22. Y
a
x= _ _—_
Interference pattern is observed at ‘P’ due to

superimposition of two rays coming out from a source *S”
as shown in the figure. The value off” for which maxima is
[Main Online April 12, 2014]

Dx = (58+8p)- (SP) neta recinto
= (RSD-(r) Se À
A> 4 Se
= -@U) = u 8

G
S= E (ss 2m.
> )(- @ I= 0) =
tr _ Ba 2(43-1)
ANG 9 7 = or ¡lod (2n-1)2
24/44 wr 4(2-45) CI
AED Gong

24. 14022 = 030

QRO reirte

n the adjacent diagram, CP represents a wavefront and

px=<o+oP AO & BP, the corresponding two rays. Find the condition
for constructive interference at P between the ray BP
AoPS = PS = d on 6 y
so = == and reflected ray OP. 20038
oP of Y CC d S|
CET) (2) cose =32/2d
Acer goss aie
cos p =)
CARa) = Co
op (c) secg—cos@ =2/d
COs: des (@) sec cos0 =42./d
Seco) Gua
15) =
aK ) AE 2 dio

25. Q

S=koxt®
5 = k(2d00) +7

aK = à
A acaso + pe

26. Q

. CE |
et AY

= A
T2 Az J

2 &

TX (an +24

u) T, €

Y

27. A_ı
A 3

(Ca

(AA.

as

A1+341
E

In an interference experiment the ratio of amplitudes of
aya “PA

coherent waves is 77
2

minimum intensities of fringes will be :

[Main 8 April 2019 1]
(a) 2 ) 18 gra (d) 9

(ey 4

1
=3 . The ratio of maximum and

28. a
Two coherent sources produce waves of different intensities
which interfere. After interference, the ratio of the maximum
intensity to the minimum intensity is 16. The intensity of the

waves are in the ratio: [Main 9 Jan. 2019 1]
(a) 16:9 Soy 25:9 (c) 4:1 (d) 5:3
au

en
= aul
= Ae

29. día Age ra Y

=%

Two beams of light having intensities / and 4/ interfere to
produce a fringe pattern on a screen. The phase difference
between the beams is 7/2 at point A and x at point B.
AT Then the difference between the resultant intensities at

EN —, Aand Bis [20015]
> @ 2 ora © 5 (d) 7

EA -r La ST 2

A = ar
ATH GG)

Ty
Ea rem] ss
Te
Ge) che tg

30. In the figure below, P and Q are two equally intense
coherent sources emitting radiation of wavelength 20 m.
The separation between P and Q is 5 m and the phase of P
is ahead of that of Q by 90°. A, B and C are three distinct
points of observation, each equidistant from the midpoint
of PQ. The intensities of radiation at A, B, C will be in the
ratio: [Main Sep. 06, 2020 (D)]

e

c
(a) 0:1:4 (b) 2:1:0 (e) 0:1:2 @) 4:1:0

32. = Sa

33. 0 = Argulen Pos : tion
P> Small Angle az

Bx > d (8) Parallel

wavefront from a

distant source.

= ax
Meaning > baren) Mama > x= (anv)
| 2 RB TA
2,À% 2x ___|— A3 4

dd rn

34. Q hf
MOI
mes ER

Consider a Young’s double slit experiment as shown in
figure. What should be the slit separation d in terms of
= Sd- 2d wavelength 2 such that the first minima occurs direct!
gi y

= in front of the slit (S,)? [Main 10 Jan 2019 II]
tr=(5-2)dg i

( 24 = (5-2)d
fo

AA À-(5-2)4

à à % à
b d
L DTS TETE CH

35. © ae
De) | IE ee
6 Brigit Spot OSE (hr)
=... (res =

Es d= 52%

A
ET Don Spot

36. y
a
O
f= Imm Interference fringes are observed on a screen by

= (son illuminating two thin slits 1 mm apart with a light source (A
D= nom nm). The distance between the screen and the slits
_ ¿3 is 100 cm. Ifa bright fringe is observed on a screen at a
ton 8 = st EN, distance of 1.27 mm from the central bright fringe, then the
Im th difference between the waves, which are reaching
0 + thi int from the slits is close t
a 7 _3 this point from the slits is close to:
On 1 27x 8° [Main Sep. 02, 2020 (1)]
An de; 127um (b) 2.87nm (c) 2nm (d) 2.05 um
= ES d (8)

ae SCS El

127 x10 Ss,

max,

Tous

37. Q DSE

Fringe Width 4 D)

P= 225 AD

247 2

ERS Br au

38. w
( Ÿ AT a

A= Son, a Young’s double slit experiment, light of 500 nm is used
d = 0:05 am to produce an interference pattern. When the distance

between the slits is 0.05 mm, the angular width (in degree)
0= N= Sox 13 ofthe fringes formed on the distance screen is close to :

y A — = 5 [Main Sep. 03, 2020 (D]

05x10 7 (a) 017 pÍOsT (9 17 (d) 007

0 0.0] Poda,

ES E Foory ge
7 “OVX ES y go

39. w
( ) N a
= 0.5m In a Young’s double slit experiment, the separation
a= between the slits is 0.15 mm. In the experiment, a source
Az 58R30m oflight ofwavelength 589 nm is used and the interference
pattern is observed on a screen kept 1.5 m away. The
D=)].5m _ separation between the successive bright fringes on the
screen is: [Main 7 Jan 2020 II]
(a) 69mm (b) 39mm (97 S9mm (d) 49mm

Be 2 - (583415 )(i.5) _

589 xo? =5.
um” x)0m9=5" Kann,

40. GEE————

YDSE with White Light

Ton)
ger OT
s y
PP Bright g=( (remy )
Viol (A= Avon) .
ist a = ()
(7 fon

41. a
O
Ad =0.5mm Ina Young's double slit experiment, slits are separated by
D=/50 cm 0.5 mm, and the screen is placed 150 cm away. A beam of
light consisting of two wavelengths, 650 nm and 520 nm,
is used to obtain interference fringes on the screen. The
mi AD =m,)\,b least distance from the common central maximum to the
d Ez point where the bright fringes due to both the wavelengths
A coincide is : [Main 2017]
mı (a) 975mm (b) 15.6mm (c) 156mm 78mm
mi = S20 _ 4
1 650 > < RTE (4)(650x10 V5)
MID ot ay as, 5 A ast

0.5x/o7

a 5% gy,
da, =78E 0

42. " w

en a Young's double slit experiment, the slits are placed
0.320 mm apart. Light of wavelength À = 500 nm is
incident on the slits. The total number of bright fringes
that are observed in the angular range — 30° < 0 < 30°
i [Main 9 Jan 2019 11]

@ 540 (b) 320 () 21 641
\ Ox = dSing

) AR 22xI93)¢;.36°
Ox = 0.16 xlp73
NA = l.exjo4

n=
516x037 2x lo”

43. 3 a
PY O nrg ——— _ ___—
In a Young's double slit experiment, 16 fringes are observed

y in a certain segment of the screen when light of wavelength
4 - [6 AD 700 nm is used. If the wavelength of light is changed to
of 400 nm, the number of fringes observed in the same
E segment of the screen would be:
à [Main Sep. 02, 2020 (ID]
d = mAb (a) 24 (b) 30 (c) 18 2
d
lLA=m2.
™= 16x 700

400 = 28

44. w
a
OR
Two coherent monochromatic point sources S, and S; of
x

wavelength À = 600 nm are placed ssyrmctrically Gai either

2 —— side of the centre of the circle as shown. The sources are

Axa dSin® Si Sy Xe E separated by a distance d = 1.8 mm. This arrangement
produces interference fringes visible as alternate bright

d (A) DA 2 SS, and dark spots on the circumference of the circle. The
d C8 angular separation between two consecutive bright spots

=——- Axz= a 1 : 6
de X= | Bam is AO. Which of the following options is/are correct?
lady. 2017
“sa
Pao = a (4x) nÀ =18nn, Xa) A dark spot will be ins
n- ed formed at the point P-

À God) = LRxi0 Hp} ALP, the order of the
Zen fringe will bemaximum

6xl57 ey The total number of

fringes produced between
P, and P, in the first
quadrant is close to 3000

The angular separation between two consecutive

bright spots decreases as we move from P, to P,
along the first quadrant

45. © mi am”: Fu

Intensity in VDSE Fr] Fr] ase

A= 4 Ao a

Teper
Y a A “

Mind oe > Peak Fe

46. a
In the Young’s double slit experiment using a

Te Toros 4T monochromatic light of wavelength A, the path difference
— E (in terms ofan integer n) corresponding to any point having
half the peak intensity is [Adv. 2013]
Ts QT N a x à
> ï MED ann nd, (@ ent,
E, = 2
Tl E) S=kax
Ls 40/E
= x
2 (8) > (ax)

E

lo
y
x
»
y

47. Ina double-slit experiment, at a certain point on the screen

pr= 2 q n point o
8 the path difference between the two interfering waves is
1
5 = KoxX=20%2 = th ofa wavelength. The ratio of the intensity of light at
r A g that point to that at the centre ofa bright fringe is:
§ A [Main 8 Jan 2020 II]
e 0853 (b) 0672 (c) 0568 (d) 0760

= 41. (+)

RYO _
(> ASL 2

La
RE

48. Slits in Different Mediums

EN
ta.
SAN Gr)
Opa

I

49. + pr ir) (a)

Ax = Warm
mA)
mys Hiden)

P=3

¡A Young's double slit interference arrangement with slits

4
5, and S, is immersed in water (refractive index = )as

shown in the figure. The
positions of maximum on
the surface of water are
given by = pm) -
d?, where À is the
wavelength of light in air
(refractive index = 1), 2dis
the separation between
the slits and m is an
integer. The value of p is
Bo

[Adv. 2015]

sn

sa

50. AX = Md- d
ax= (4-1) d
“YES
<= 1259)
3

of light used) and refractive index u = 1.5 is inserted
between one of the slits and the screen in Young’s double
slit experiment. At a point on the screen equidistant from
the slits, the ratio of the intensities before and after the
introduction of the glass plate is :

[Main Online April 25, 2013]
(a) 2:1 (b) 1:4 (c) 4:1 4:3

I= 41, ar

FAL x E 2.
S= hare Mar 230 > 2)
3

52. Q Diffraction SGT widen
For Minima af P

|
=A
la : «| :
Ms is a
37 ee
<n Sh
ar be : Minima
Sing, —
FEN 32 ne

53. 10/62.5

sind

54. x 6
Xx lo
E Ilm

0. 5x10" nm,

‘The angular width ofthe central maximum in a single slit
diffraction pattern is 60°. The width of theslit is 1 um. The
slit is illuminated by monochromatic plane waves. If
another slit of same width is made near it, Young's fringes

can be observed on a screen placed at a distance 50 cm

from the slits. Ifthe observed fringe width is 1 cm, what is
slit separation distance?

(i.e. distance between the centres of each slit.) [Main 2018]
9 25um (b) SOum (c) 75um (d) 100um

Ea = 1 alo?
de

57. © DE — ee ——

AR

Polarizing filter Le eS
&

Axis Polarizing filter

58. Q

Polarizer:

Polarizing filter

‘AXIS Polarizing filter

59. = y
Q Polarizer

Polarizing filter

Malu's Law

60. Y
2
Unpolarized light of intensity I passes through an ideal
polarizer A. Another indentical polarizer B is noe behind

A. The intensity of light beyond B is found to be > Now
another identical polarizer C is placed between A and B.
‘The intensity beyond B is now found to be |. The angle
8
A = Te between polarizer A and C is: [Main 2018]
A B ? ar SE Ww Ww
E. El Ee La Gg
{ WS. 8
ie
AL

T= Le 2=089 ne

62. w
a
$$
Unpolarized light of intensity I is incident on a system of

two polarizers, A followed by B. The intensity of emergent
= = I Cos © light is 1/2. Ifa third polarizer C is placed between A and B,
the intensity ofemergent light is reduced to 1/3. The angle
between the polarizers A and C is 6. Then

3
( 2 ly = Gong [Main Online April 16, 2018]
) 2 1/4 1 1/4
PL (b) oos0=(1)

ya 22
(c) oosd=(1) (d) coso=(3)

64. w
a
+
“Two beams, A and B, of plane polarized light with mutually
perpendicular planes of polarization are seen through a
polaroid. From the position when the beam A has maximum
intensity (and beam B has zero intensity), a rotation of
polaroid through 30° makes the two beams appear equally
bright. If the initial intensities of the two beams are I, and

I
1, respectively, then rel equals: [Main 2014]
B

3 1
(a) 3 073 (e) 1 03

66. Abeam of unpolarised light of intensity I, is passed
through a polaroidAand then through another polaroid B
which is oriented so that its principal plane makes an angle
of 45° relative to that of A. The intensity of the emergent
light is [Main 2013]
(a) Ip (0) Iy2 © 1/4 (a) 1ÿ8

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Unacademy Atoms
5 244 subscribe
Description

Unacademy Atoms is the one-stop solution
to your JEE needs! India's top Educators
help you in your preparation to excel in
your examinations with LIVE sessions,
interactive quizzes, strategies, tips and free
notes, all waiting for you.

tme/unacademyatoms.
ite

Notifications
on

69. llow the Profile on

e Ap

Abhilash Sharma 9 /

Rising Star in IIT JEE

O Best Rated Physics Teacher Award, B.Tech from NIT Calicut, 7+years of Teaching
experience. Telegram & IG: abhilashsharmaiitjee

146K watch mins 106K watch mins (last 30 days) 1K Followers 46 Dedications MID

70. New Revision Series for FREE
Age

HINGLISH PHYSICS HINGLISH PHYSICS HINGLISH PHYSICS
Electrostatics - Dipole(JEE Mains & Electrostatics - Earthing (JEE Mains Relation between Field & Potential,
Advanced 2022) & Advanced 2022) Equipotential Surface

O enrollments 0 enrollments 0 enrollments

Starts on Nov 25, 2021 Starts on Nov 23, 2021 Starts on Nov 23, 2021

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Unlock 20% off on all
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se code
"TEC Apply

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BY
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