Wave Optics Test

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Wave Optics Test - 64

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Weekly Quiz Competition

Question 1
1 / -0

A plane wavefront $$(\lambda=6 \times 10^{-7}\ m)$$ falls on a slit $$0.4\ mm$$ wide. A convex lens of focal length $$0.8\ m$$ placed behind the slit focuses the light on a screen. What is the linear diameter of second maximum

A
$$6\ mm$$

B
$$12\ mm$$

C
$$3\ mm$$

D
$$9\ mm$$

Solution

For secondary maxima $$d \sin \theta =\dfrac{5 \lambda}{2}$$
$$\Rightarrow d \theta=d.\dfrac{x}{D(\approx f)}=\dfrac{5 \lambda}{2}$$
$$\Rightarrow 2x=\dfrac{5 \lambda f}{d}=\dfrac{5 \times 0.8 \times 10^{-7}}{4 \times 10^{-4}}=6 \times 10^{-3}\ m=6\ mm$$
Question 2
1 / -0

The phase difference between incident wave and reflected wave is $$180^o$$ when light ray

A
Enters into glass from air

B
Enters into air from glass

C
Enters into glass from diamond

D
Enters into water from glass

Solution

When light reflect from denser surface phase change of $$\pi$$ occurs
Question 3
1 / -0

Following figure shows sources $$S_{1}$$ and $$S_{2}$$ that emits light of wavelength $$\lambda$$ in all directions. the sources are exactly in phase and are seperated by a distance equal to $$1.5\lambda .$$ If we start at the indicated start point abd travel along path $$1$$ and $$2,$$ the interference produce a maxima all along

A
Path $$1$$

B
Path $$2$$

C
Any path

D
None of these

Solution

At any point along the path $$1,$$ path difference between the waves is $$0.$$
Hence maxima is obtained all along the path $$1.$$
At any point along the path $$2$$, path difference is $$1.5\lambda$$ which is odd multiple of $$\dfrac{\lambda}{2},$$ so minima is obtained all along the path $$2.$$
Question 4
1 / -0

Which of the following is not a property of light

A
It requires a material medium for propogation

B
It can travel through vacuum

C
It involves transportation of energy

D
It has finite speed

Solution

LIght is electromagnetic in nature it does not require any material medium for its propogation.
Question 5
1 / -0

In the Young's double slit experiment, for which colour the fringe width is least

A
Red

B
Green

C
Blue

D
Yellow

Solution

$$\beta \propto \lambda$$
Question 6
1 / -0

In a Young's experiment, monochromatic light is used to illuminate the two slits $$A$$ and $$B$$. Interference fringes are observed on a screen placed in front of the slits. Now if a thin glass plate is placed normally in the path of the beam coming from the slit

A
The fringes will disapear

B
The fringes width will increase

C
The fringes width will increase

D
There will be no change in the fringe width but the pattern shifts

Solution

In the presence of thin glass plate, the fringe pattern shifts, but no change in fringe width.
Question 7
1 / -0

The sun is rotating about its own axis. The spectral lines emitted from the two ends of its equator, for an observer on the earth, will show

A
Shift towards red end

B
Shift towards violet end

C
Shift towards red end by one line and towards violet end by other

D
No shift

Solution
Question 8
1 / -0

A star emits light of $$5500 \overset{o}{A}$$ wavelength. Its appears blue to an observer on the earth, it means

A
Star is going away from the earth

B
Star is stationary

C
Star is coming towards earth

D
None of the above

Solution

Blue radiations have the wavelength around $$4600\overset{o}{A}$$ . It shows that apparent wavelength is smaller than the real wavelength. It means that the star is proceeding towards earth.
Question 9
1 / -0

In the set up shown in fig the two slits, $$S_{1}$$ and $$S_{2}$$ are not equidistant from the slits $$S.$$ The central fringe at $$O$$ is them

A
Always bright

B
Always dark

C
Either dark or bright depending on the position of $$S$$

D
Neither dark nor bright.

Solution

If path difference $$\Delta =(SS+SO)-(SS+SO)=n\lambda n=0,1,2,3,...$$ the central fringe at $$O$$ is a bright fringe and if the path difference $$\Delta=\left(n-\dfrac{1}{2}\right)\lambda n=1,2,3,...$$ the central bright fringe will be a dark fringe.
Question 10
1 / -0

Specific rotation of sugar solution is $$0.01$$ SI units. $$200\ kgm^{-3}$$ of impure sugar solution is taken in a polarimeter tube of length $$0.25\ m$$ and an optical rotation of $$0.4\ rad$$ is observed. The percentage of purity of sugar is the sample is

A
$$80\%$$

B
$$89\%$$

C
$$11\%$$

D
$$20\%$$

Solution

Specific rotation
$$(\alpha)=\dfrac{\theta }{lc}$$

$$\Rightarrow c=\dfrac{\theta}{\alpha l}$$

$$=\dfrac{0.4}{0.01\times 0.25}=160\ kg/m^{3}$$

Now percentage purity of sugar solution
$$\dfrac{160}{200}\times 100=80\%$$

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Re-Attempt Weekly Quiz Competition

Wave Optics Test - 64

Result

Wave Optics Test - 64

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SHARING IS CARING

Question 1

$$6\ mm$$

$$12\ mm$$

$$3\ mm$$

$$9\ mm$$

Solution

Question 2

Enters into glass from air

Enters into air from glass

Enters into glass from diamond

Enters into water from glass

Solution

Question 3

Path $$1$$

Path $$2$$

Any path

None of these

Solution

Question 4

It requires a material medium for propogation

It can travel through vacuum

It involves transportation of energy

It has finite speed

Solution

Question 5

Red

Green

Blue

Yellow

Solution

Question 6

The fringes will disapear

The fringes width will increase

The fringes width will increase

There will be no change in the fringe width but the pattern shifts

Solution

Question 7

Shift towards red end

Shift towards violet end

Shift towards red end by one line and towards violet end by other

No shift

Solution

Question 8

Star is going away from the earth

Star is stationary

Star is coming towards earth

None of the above

Solution

Question 9

Always bright

Always dark

Either dark or bright depending on the position of $$S$$

Neither dark nor bright.

Solution

Question 10

$$80\%$$

$$89\%$$

$$11\%$$

$$20\%$$

Solution

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