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Light Test - 39

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following animal's eyes are very small and they are also able to look all around

A
Rat

B
Snails

C
Crab

D
Snakes

Solution

The eyes of a crab makes it look like an animal from outer space. The two stalks that seem to be growing out on top of the head are the eyes of a crab. By means of thousands of light-sensitive facets on each eye stalk, the crab can see all around.
Question 2
1 / -0

There is a point in our eyes where no image is formed. That point is known as blind spot. Which animal do not have this blind spot?

A
Fish

B
Ostrich

C
Octopus

D
Rat

Solution

The Octopus has a single layer of receptor cells that project images back to the brain through the optic nerve. The Octopus doesn't have blind spots because their optic nerves do not pass through the receptors but instead from behind them.
Question 3
1 / -0

Two plane mirrors are placed such they make $$\displaystyle { 0 }^{ \circ }$$ angle with each other. How many images, of an object placed between them, are formed?

A
$$0$$

B
$$2$$

C
$$1$$

D
$$Infinite$$

Solution

When two plane mirrors are placed at $$\displaystyle { 0 }^{ o }$$ to each other, that means they are actually parallel to each other. And, two parallel mirrors form an infinite number of images.
Question 4
1 / -0

A bird having large cornea and a large pupil to allow more light in the eye.

A
Owl

B
Honeybee

C
Eagle

D
Parrot

Solution

An owl has a large cornea and a large pupil to allow more light to enter into the eyes. Therefore they are able to see very well even at night.
Question 5
1 / -0

If an object is placed symmetrically between two plane mirrors, inclined at an angle of $$72^0$$, then the total number of images formed is:

A
5

B
4

C
2

D
Infinite

Solution

The angle between the two mirrors, $$\theta=72^0$$
So, number of images formed: $$n=\dfrac{360}{\theta}-1=\dfrac{360}{72}-1=5-1=4$$
$$4$$ images will be formed.
Question 6
1 / -0

How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 100 cm?

A
2

B
3

C
0

D
Infinite

Solution

The mirrors are parallel to each other. So, infinite images of the candle will be formed.
Number of images does not depend on the mutual distance of the parallel mirrors.
Question 7
1 / -0

In periscopes, the parallel rays entering the cylindrical tube from the upper end from an object, strike the plane mirror at an angle of _____ and hence are reflected through an angle of ________.

A
$$30^0,30^0$$

B
$$45^0,45^0$$

C
$$45^0,30^0$$

D
$$90^0,90^0$$

Solution

As seen in diagram.
In periscopes, the parallel rays which enter the cylindrical tube from the upper end from an object, strike the plane mirror at an angle of $$45^0$$ and hence are reflected through an angle of $$45^0$$. These reflected rays strike the second mirror at an angle of $$45^0$$ and are further reflected through an angle of $$45^0$$.
Question 8
1 / -0

Fill in the blank:

When angle of incidence increases, glancing angle of incidence ________.

A
decreases

B
increases

C
remains same

D
becomes zero

Solution

Glancing angle is the angle between incident ray and reflecting surface and it is represented by $$g$$.
Angle of incidence $$+$$ Glancing angle of incidence $$=90^0$$
So, Glancing angle of incidence $$=90^0 -$$ Angle of incidence
This means, when angle of incidence increases, glancing angle of incidence decreases,
Question 9
1 / -0

In Braille system how are the dots made?

A
They can be made with help of hands

B
They can be made with the help of printer

C
They can be made with the help of typewriter

D
All the above

Solution

Braille is a tactile writing system used by people who are visually impaired. It is traditionally written with embossed paper.
The Braille text are prepared with help of hand or by machines,like printing machines or typewriters. Braille text are prepared with the help of 63 dot patterns or characters .
Question 10
1 / -0

How are dots arranged in cells of Braille system?

A
Arranged in cells of two vertical rows of three dots each

B
Arranged in cells of three vertical rows of three dots each

C
Arranged in cells of two vertical rows of two dots each

D
Arranged in four vertical rows of two dots each

Solution

Braille system has $$63$$ dot patterns or characters. Each character represents a letter, a combination of letters, a common word, or a grammatical sign. Dots are arranged n cells of two vertical rows of three dots each.

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Re-Attempt Weekly Quiz Competition

Light Test - 39

Result

Light Test - 39

Score

-

Rank

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SHARING IS CARING

Question 1

Rat

Snails

Crab

Snakes

Solution

Question 2

Fish

Ostrich

Octopus

Rat

Solution

Question 3

$$0$$

$$2$$

$$1$$

$$Infinite$$

Solution

Question 4

Owl

Honeybee

Eagle

Parrot

Solution

Question 5

5

4

2

Infinite

Solution

Question 6

2

3

0

Infinite

Solution

Question 7

$$30^0,30^0$$

$$45^0,45^0$$

$$45^0,30^0$$

$$90^0,90^0$$

Solution

Question 8

decreases

increases

remains same

becomes zero

Solution

Question 9

They can be made with help of hands

They can be made with the help of printer

They can be made with the help of typewriter

All the above

Solution

Question 10

Arranged in cells of two vertical rows of three dots each

Arranged in cells of three vertical rows of three dots each

Arranged in cells of two vertical rows of two dots each

Arranged in four vertical rows of two dots each

Solution

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