Light Test

Result

Light Test - 37

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Weekly Quiz Competition

Question 1
1 / -0

When a ray of light strikes a plane mirror along the normal, the angle of incidence is -

A
$$\displaystyle 90^{\circ}$$

B
zero

C
$$\displaystyle 45^{\circ}$$

D
none of these

Solution

Angle of incidence is the angle made by incident ray and normal to the mirror. Here, the ray incidents along normal so,
From the figure, angle of incidence$$=0^{\circ}$$.
Question 2
1 / -0

Which of the following is a $$\text{non-luminous}$$ body?

A
Fire

B
Sun

C
Star

D
Tree

Solution

Fire, Sun and star have produce visible light, But Tree do not produce visible light So Tree will be non-luminous body.
Question 3
1 / -0

Cold light is _______________.

A
Bioluminescent light

B
Sunlight

C
Moonlight

D
Chemical or oil light

Solution

Bioluminescence is a "cold light." Cold light means less than $$20%$$ of the light generates thermal radiation or heat. These bioluminescent marine species include fish, bacteria, and jellies. Some bioluminescent organisms, including fireflies and fungi, are found on land.
Question 4
1 / -0

The path along which light travels in a homogenous medium is called the

A
beam of light

B
ray of light

C
pencil of light

D
none of these

Solution

Light rays are defined to propagate in a rectilinear path as they travel in a homogeneous medium. This path is known as ray of light..
Question 5
1 / -0

The angle between reflected ray and the _______ is called angle of reflection

A
normal

B
incident ray

C
reflecting surface

D
none of the above

Solution

Angle of reflection is defined as the angle made by the reflected ray with the normal of reflecting surface.
Question 6
1 / -0

A star is a/an _____ source of light

A
natural

B
artificial

C
false

D
absolute

Solution

Natural sources of light are the sources that emit light on their own without any man-made control. For example the Sun, stars, etc.
Question 7
1 / -0

Assertion: If the angle between the two plane mirror is $$72^o$$ and the object is asymmetrically placed between the two mirrors, then 5 images of the object will be formed.
Reason: For a given system of mirrors the total number of images formed due to successive reflection is equal to either $$\dfrac{360^o}{\theta}$$ or $$\dfrac{360^o}{\theta}-1$$ accordingly as $$\dfrac{360^o}{\theta}$$ is odd or even respectively.

A
If both Assertion 'and Reason are correct and Reason is the correct explanation of Assertion

B
If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion

C
If Assertion is correct but Reason is incorrect

D
If Assertion is incorrect but Reason is correct

Solution

The number of image formed is either $$n=\dfrac{360^{o}}{\theta}$$ for n=odd or $$n-1 $$ for n=even

Here, $$\theta=72^{o}$$

Hence, $$n=\dfrac{360^{o}}{72^{o}}=5$$ which is odd.

Hence, number of image formed=$$5$$

Hence, both assertion and reason are correct and reason is correct explanation of assertion.

Answer-(A)
Question 8
1 / -0

Select the odd one out (book, chair, table, burning candle)

A
burning candle

B
book

C
chair

D
table

Solution

It is a luminous object rest all are non-luminous
Question 9
1 / -0

The incident ray,reflected ray and the normal ray, all lie on the ______ plane.

A
Different

B
Same

C
Mutually perpendicular

D
Orthogonal

Solution

According to laws of reflection, the incident ray reflected ray, and the normal ray lies on the same plane.
Question 10
1 / -0

The angle between incident ray and reflected ray is $$\displaystyle { 90 }^{ o }$$. Find the angle of reflection.

A
$$\displaystyle { 90 }^{ o }$$

B
$$\displaystyle { 45 }^{ o }$$

C
$$\displaystyle { 30 }^{ o }$$

D
Can't be predicted

Solution

According to law of reflection
The angle of incidence $$=$$ the angle of reflection $$=\theta$$, say.
So, the angle between the incident and the reflected ray$$=\theta+\theta=2\theta$$
As per given condition, $$2\theta={90}^{0}$$
or, $$\theta={45}^{0}$$
The angle of reflection is $$45^0$$

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Re-Attempt Weekly Quiz Competition

Light Test - 37

Result

Light Test - 37

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SHARING IS CARING

Question 1

$$\displaystyle 90^{\circ}$$

zero

$$\displaystyle 45^{\circ}$$

none of these

Solution

Question 2

Fire

Sun

Star

Tree

Solution

Question 3

Bioluminescent light

Sunlight

Moonlight

Chemical or oil light

Solution

Question 4

beam of light

ray of light

pencil of light

none of these

Solution

Question 5

normal

incident ray

reflecting surface

none of the above

Solution

Question 6

natural

artificial

false

absolute

Solution

Question 7

If both Assertion 'and Reason are correct and Reason is the correct explanation of Assertion

If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion

If Assertion is correct but Reason is incorrect

If Assertion is incorrect but Reason is correct

Solution

Question 8

burning candle

book

chair

table

Solution

Question 9

Different

Same

Mutually perpendicular

Orthogonal

Solution

Question 10

$$\displaystyle { 90 }^{ o }$$

$$\displaystyle { 45 }^{ o }$$

$$\displaystyle { 30 }^{ o }$$

Can't be predicted

Solution

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