Light (Physics) (Part-1)

 

Total Questions: 50

21. In an image formed by a mirror, the left of the object appears on the right and the right appeares on the left. This is called as: [S.S.C. JE Mechanical Exam 27.10.2020 (Shift-I)]

Correct Answer: (b) Lateral inversion
Solution:

When an image is formed by a mirror such that the left side of the object appears on the right and the right side appears on the left, this phenomenon is called lateral inversion.

Lateral inversion occurs because a plane mirror reverses the image along the axis perpendicular to its surface, leading to the perception that left and right are swapped in the mirror image.

This is why words like "AMBULANCE" are written in reverse on vehicles, so they appear correctly in a driver's rear-view mirror

22. The image formed by a plane mirror is always_________. [S.S.C. Online MTS (T-I) 10.10.2017 (Shift-I)]

Correct Answer: (b) Erect
Solution:A plane mirror is a flat, smooth mirror that reflects light without converging or diverging it. The image it produces has a few key characteristics:

Erect: The image appears upright, meaning it's not upside down. If you look at yourself in a plane mirror, your head appears at the top of the image and your feet at the bottom. This is the opposite of an inverted image, which is flipped vertically.

Virtual: The image is formed behind the mirror where the light rays only appear to meet, but don't actually converge. You can't project a virtual image onto a screen.

Laterally Inverted: The image is flipped horizontally, as if it were a reflection in water. For example, your right hand appears as the left hand of your reflection.

Same Size: The image is the same size as the object.

Same Distance: The image appears to be the same distance behind the mirror as the object is in front of it.

23. The size of the image formed by a plane mirror is always_______ to/than the object. [S.S.C. Online MTS (T-I) 9.10.2017 (Shift-I)]

Correct Answer: (a) Equal
Solution:The size of the image formed by a plane mirror is always equal to the size of the object.

24. The total number of images formed by two mirrors inclined at 120° to each other is _______ . [S.S.C. Online Graduation Level (T-I) 5.03.2020 (Shift-II)]

Correct Answer: (c) 2
Solution:The total number of images formed by two mirrors inclined at 120° to each other is 2.
This can be determined using the formula:
n=(360∘/θ)−1
where θ=120∘
n=(1360∘/120∘)−1=3−1=2
So, 2 images are formed when two mirrors are inclined at 120° to each other

25. The image formed by a plane mirror is always. [S.S.C. Online MTS (T-I) 21.08.2019 (Shift-II)]

Correct Answer: (a) virtual and erect
Solution:A plane mirror is a flat, smooth mirror that reflects light without converging or diverging it. The image it produces has a few key characteristics:

Erect: The image appears upright, meaning it's not upside down. If you look at yourself in a plane mirror, your head appears at the top of the image and your feet at the bottom. This is the opposite of an inverted image, which is flipped vertically.

Virtual: The image is formed behind the mirror where the light rays only appear to meet, but don't actually converge. You can't project a virtual image onto a screen.

Laterally Inverted: The image is flipped horizontally, as if it were a reflection in water. For example, your right hand appears as the left hand of your reflection.

Same Size: The image is the same size as the object.

Same Distance: The image appears to be the same distance behind the mirror as the object is in front of it.

26. Which of the following is the instrument used in submarines to view objects above sea level? [S.S.C. Online MTS (T-I) 14.08.2019 (Shift-III)]

Correct Answer: (d) Periscope
Solution:The instrument used in submarines to view objects above sea level is called a periscope.

A periscope allows submarine crews to observe the surface while remaining submerged, using a system of mirrors or prisms to direct light from above the water down to the viewer inside the submarine.

27. A periscope makes use of: [S.S.C. JE Mechanical Exam 27.10.2020 (Shift-I)]

Correct Answer: (d) Two-plane mirrors
Solution:The periscope is made up of two plane mirrors.
  • It is an optical instrument through which the observer can see the environment around him.
  • Periscope works on the basis of the laws of reflection.
  • Periscopes are used in submarines, warships, cruisers, artillery, etc.

28. An image formed on a screen is called a_________ image, whereas the image formed by a plane mirror is called a_________ image. [S.S.C. Online MTS (T-I) 26.10.2021 (Shift-II)]

Correct Answer: (c) real; virtual
Solution:If an image of an object is formed on the screen by a lens or mirror, it is called a real image,
whereas the image formed by a plane mirror cannot be obtained on the screen, so such an image is called a virtual image.

29. Purpose of an optical filter is to__________. [S.S.C. Online Graduation Level (T-I) 30.08.2016 (Shift-II)]

Correct Answer: (d) transmit or absorb light of different colours
Solution:Optical fibers are hollow, flexible, transparent, tube- like wires made from plastic or glass and have a very small diameter.

Optical fibers are used to transmit light and are predominantly used in fiber-optic communications because they facilitate transmission over longer distances and at higher bandwidth levels.

What are Fiber Optics and How Do They Work? | Coherent

30. In an optical fibre the signal is transmitted_________. [S.S.C. Online Graduation Level (T-I) 1.09.2016 (Shift-II)]

Correct Answer: (c) due to total internal reflection
Solution:Optical fibers are extremely thin cylindrical hollow tubes made of glass (silica) or plastic, which work on the principle of total internal reflection of light.

There is no loss of light energy in them.

What are Fiber Optics and How Do They Work? | Coherent