Wave Optics Test

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Wave Optics Test - 16

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Weekly Quiz Competition

Question 1
1 / -0

The least resolvable angle by a telescope using objective of aperture 5 m is nearly ($$\lambda = 4000A^{\circ}$$)

A
$$\dfrac{1}{50^{\circ}}$$

B
$$\dfrac{1}{50}$$ minute

C
$$\dfrac{1}{50}$$sec

D
$$\dfrac{1}{500}$$sec

Solution

$$R= \dfrac{9}{1.22\lambda }$$

$$\dfrac{1}{\Delta \theta }= \dfrac{5}{1.22\times 4000\times 10^{-10}}$$

$$\Delta \theta = \dfrac{1}{50}sec$$
Question 2
1 / -0

Wave front formed by the collimator of a spectrometer

A
Plane

B
Spherical

C
Cylindrical

D
Paraboloidal

Solution

Wave front formed by the collimator of a spectrometer is a plane wave front, when r lit is in the focus.
Question 3
1 / -0

The resolving power of human eye is :

A
$$\approx 1'$$

B
$$\approx 1^{0}$$

C
$$\approx 10"$$

D
$$\approx 5"$$

Solution

$${\textbf{Explanation:}}$$
$$\bullet$$ As we know the visibility of the human eye is limited up to a distance.
$$\bullet$$ It is known to us that the normal pupil size of any human being is 4 mm. This measurement sets a minimum resolution approximately 1' to 2′.
$$\bullet$$ When we want to pull small objects closer to our eyes, we aim to see them properly. But it is often seen that after crossing a certain distance the particles become unclear no matter how much closer it is to our eyes.
$$\bullet$$ This signifies that there is a minimum distance of comfortable viewing. This distance is roughly calculated as 25 cm.

$${\textbf{Correct option: A}}$$
Question 4
1 / -0

Assertion : Resolving power of a telescope is more if the diameter of the objective lens is more.
Reason : Objective lens of large diameter collects more light

A
Both Assertion and Reason are correct and Reason is correct explanation of Assertion

B
Assertion and Reason both are correct but Reason is not correct explanation of Assertion.

C
Assertion is true but Reason is false.

D
Both Assertion and Reason are false.

Solution

Resolving power of a telescope is more if the diameter of the objective lens is more because $$R=\dfrac{a}{1.22 \lambda}$$
where, a is diameter of the objective. objective lens of large diameter collects more light but does not increase the resolving power of the telescope because resolving power increases when angular separation increases.
Question 5
1 / -0

The resolving power of a telescope depends on :

A
length of telescope

B
focal length of objective

C
diameter of the objective

D
focal length of eyepiece

Solution

Resolving power of telescope $$R=\dfrac{1}{\Delta \theta}=\dfrac{a}{1.22 \lambda}$$
where, $$\Delta \theta$$ is angular separation between two objects.
$$a$$ is the diameter of the objective.
$$\lambda$$ is wavelength of light.
So, clearly resolving power of a telescope depends on diameter of the objective.
Question 6
1 / -0

Resolving power of a telescope increases with :

A
increase in focal length of eyepiece

B
increase in focal length of objective

C
increase in aperture of eyepiece

D
increase in aperture of objective

Solution

Resolving power of a telescope:
$$R=\dfrac{a}{1.22 \lambda}$$
where, $$a$$ is diameter of the objective
so, $$R$$ increases when a is increased and $$a$$ increases when aperture of objective is increased
Question 7
1 / -0

The air film in a Newton's ring apparatus is replaced by an oil film. The radii of the rings

A
remains the same

B
increases

C
decreases

D
none of the above

Solution

Radius of nth order Newton's ring is proportional to $$\sqrt{\lambda}$$ which decreases in oil since $$\lambda=\dfrac{\lambda_{vacuum}}{\mu}$$. Thus the radius of newton's ring decreases in oil film.
Question 8
1 / -0

The figure shows diffraction pattern of two nearby points. The two points are

A
not resolved

B
just resolved

C
clearly resolved

D
none

Solution

Since there are a number of crests in between the peaks of the two points, they clearly do not immerse into each other at all, thus they are clearly resolved.
Question 9
1 / -0

Huygens principle of secondary waves

A
allow us to find the focal length of a thick convex lens.

B
give us the magnifying power of the microscope.

C
is a geometrical method to find, the position of a wave front.

D
is used to determine the velocity of light.

Solution

Huygens's Principle states that every point on a wavefront is a source of secondary wavelets, which spread forward at the same speed.
Thus is enables to find the position of wavefront.
Question 10
1 / -0

Fill in the blanks:
According to Newton, different colors of light are due to the difference in _______ of the corpuscles.

A
mass

B
nature

C
shape

D
size

Solution

Corpuscles are single, infinitesimally small, particles which have shape, size, color, and other physical properties.

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Wave Optics Test - 16

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Wave Optics Test - 16

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SHARING IS CARING

Question 1

$$\dfrac{1}{50^{\circ}}$$

$$\dfrac{1}{50}$$ minute

$$\dfrac{1}{50}$$sec

$$\dfrac{1}{500}$$sec

Solution

Question 2

Plane

Spherical

Cylindrical

Paraboloidal

Solution

Question 3

$$\approx 1'$$

$$\approx 1^{0}$$

$$\approx 10"$$

$$\approx 5"$$

Solution

Question 4

Both Assertion and Reason are correct and Reason is correct explanation of Assertion

Assertion and Reason both are correct but Reason is not correct explanation of Assertion.

Assertion is true but Reason is false.

Both Assertion and Reason are false.

Solution

Question 5

length of telescope

focal length of objective

diameter of the objective

focal length of eyepiece

Solution

Question 6

increase in focal length of eyepiece

increase in focal length of objective

increase in aperture of eyepiece

increase in aperture of objective

Solution

Question 7

remains the same

increases

decreases

none of the above

Solution

Question 8

not resolved

just resolved

clearly resolved

none

Solution

Question 9

allow us to find the focal length of a thick convex lens.

give us the magnifying power of the microscope.

is a geometrical method to find, the position of a wave front.

is used to determine the velocity of light.

Solution

Question 10

mass

nature

shape

size

Solution

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