Wave Optics Test

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Wave Optics Test - 55

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Question 1
1 / -0

Consider the figure shown. A system consists of a coaxial glass slab slab (with convex lens of focal length $$f_1$$ inside) and a concave lens of focal length $$f_2$$, separated by a distance $$'d'$$. A parallel beam of light incident on the glass slab and correspondingly a parallel beam of light emerges out of the concave lom Then the possible correct options are

A
$$d > f_1$$

B
$$d < f_1$$

C
$$d > f_1-f_1$$

D
$$d < f_2$$
Question 2
1 / -0

Consider Fraunhoffer diffraction pattern obtained with a single slit illuminate incidance. At the angular position of the first diffraction minimum in the phase( radian) between the wavelets from the opposite edges of the slit is

A
$$\dfrac {\pi} 4$$

B
$$\dfrac {\pi} 2$$

C
$$ {\pi}$$

D
$$2\pi$$

Solution

The correct answer should be option d.
Question 3
1 / -0

Intensity of the central maximum in Youngs double slit experiment is I. When one of the slit is closed the intensity is $$I_0$$. The ratio $$I / I_0$$ is........

A
$$2: 1$$

B
$$1: 2$$

C
$$4: 1$$

D
$$1: 4$$

Solution

Intensity is proportional to square of amplitude of wave$$.$$
If amplitude of wave of each source is a$$,$$ then after superposition intensity is proportional to $$(2a)^2$$ $$i.e.,$$ $$4a^2.$$
If one source is closed$$,$$ there is no superposition $$,$$
So$$,$$ intensity is proportional to $$a^2.$$
then$$,$$ $$l/4l=1/4=1:4$$
Hence,
option $$(D)$$ is correct answer.
Question 4
1 / -0

If the frequency of the source is doubled in Young's double slit experiment, then fringe width $$( \beta )$$ will be-

A
unchanged

B
$$\beta / 2$$

C
$$2 \beta$$

D
$$3 \beta$$

Solution

$$\begin{array}{l} fringe\, \, width\, \, \beta =\frac { { \lambda D } }{ \alpha } \\ And\, \, \, \lambda =\frac { c }{ f } \\ so,\, \, \, \, \, \beta =\frac { { CD } }{ { fd } } \\ Hence,\, \, \beta \propto \frac { 1 }{ f } \end{array}$$
If frequency double, fringe width $$(\beta)$$ is halved
Option $$B$$ is correct.
Question 5
1 / -0

The intensity at the maximum in Young's double slit experiment is $$I_o$$. The distance between two slits is d = 5 $$\lambda$$, where $$\lambda$$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance D = 10d?

A
$$I_o$$

B
$$\dfrac{I_o}{4}$$

C
$$\dfrac{3}{4} I_o$$

D
$$\dfrac{I_o}{2}$$

Solution

In the given, $${ S }_{ 1 }$$ & $${ S }_{ 2 }$$ are the two different slits.
Given,
$$d=5\lambda $$
Here, $${ I }_{ max }={ I }_{ 0 }$$
Path difference$$=\cfrac { d{ Y }_{ 0 } }{ D } =\cfrac { d\times \cfrac { d }{ 2 } }{ 10\lambda } =\cfrac { d }{ 20 } =\cfrac { \lambda }{ 4 } $$
[$$d=5\lambda $$]
For path difference $$\cfrac { \lambda }{ 4 } $$,Phase difference is $$d=\cfrac { 2\pi }{ \lambda } \times \cfrac { \lambda }{ 4 } =\cfrac { \pi }{ 2 } =90$$
We know, $$I={ I }_{ 0 }\cos ^{ 2 }{ \cfrac { 90 }{ 2 } } $$
$$I={ I }_{ 0 }{ \left( \cfrac { 1 }{ \sqrt { 2 } } \right) }^{ 2 }$$
$$I=\cfrac { { I }_{ 0 } }{ 2 } $$
Question 6
1 / -0

What is the effect on the interference fringes in Young's double slit experiment if the source slit is moved closer to the double slit plane?

A
The fringe width increases

B
The fringe width decreases

C
The fringes become more distinct

D
The fringes become less distinct

Solution
Question 7
1 / -0

Through which character we can distnguish the light waves from sound waves.

A
Interference

B
Refraction

C
Polarisation

D
Reflection

Solution

Polarisation is not shown by sound waves.
Question 8
1 / -0

In YDSE if white is used then.

A
except center, there will be spectrum

B
except center no spectrum any where

C
spectrum every where

D
spectrum at center only

Solution
Question 9
1 / -0

When an unpolarized light of intensity $$I_0$$ is incident on a polarizing sheet the intensity of the light which does not get transmitted is?

A
Zero

B
$${I}_{0}$$

C
$$\cfrac{1}{2}{I}_{0}$$

D
None
Question 10
1 / -0

Huygen's theory of secondary waves can be used of find-

A
Velocity of light

B
The wavelength of light

C
Wave front geometrically

D
Magnifying power of microscope

Solution

The correct answer should be option c.