Which among the following is an example of Diffraction?

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RRB NTPC Exam 27 Jan 2021 click here to view all questions

Which among the following is an example of Diffraction?

AThe blue color of the sky

BThe twinkling of the stars

CThe Tyndall effect

DRainbow patterns found on a CD

Akhilesh ? Apr 1 '25 at 20:40

correct answer is: option d (Rainbow patterns found on a CD)
Explanation: Diffraction is the bending of waves (including light) as they pass around an obstacle or through an aperture. Rainbow patterns found on a CD are caused by the diffraction of white light by the closely spaced tracks on the CD's surface, which act as a diffraction grating.

• Option a: The blue color of the sky is due to Rayleigh scattering, where shorter wavelengths of light (like blue) are scattered more by the atmosphere's particles.
• Option b: The twinkling of the stars is caused by atmospheric refraction, where light from stars is bent as it passes through different layers of the atmosphere with varying densities.
• Option c: The Tyndall effect is the scattering of light by particles in a colloid or suspension, making the beam of light visible. This is also a scattering phenomenon, but not diffraction.

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What is the cause of the formation of 'Aurora Borealis'?

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RRB NTPC Exam 27 Jan 2021 click here to view all questions

What is the cause of the formation of 'Aurora Borealis'?

AIt occurs when sunlight hits ice crystals in cirrus clouds that are very high in the sky

BIt is formed when there s a reflection of light from the sun and the moon form various small ice crystals suspended in the air

Cthe collisions between gaseous particles in the Earth s atmosphere with charged particles released from the sun s atmosphere

DIt is formed when a concentrated bright spot is seen on one or both sides of the sun

Akhilesh ? Apr 1 '25 at 20:38

correct answer is: option c [the collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere]
Explanation: The Aurora Borealis (Northern Lights) is caused by collisions between charged particles (electrons and protons) released from the sun's atmosphere and gaseous particles (primarily oxygen and nitrogen) in the Earth's atmosphere. These collisions excite the atmospheric gases, causing them to emit light of various colors.

• Option a: This describes a halo, an optical phenomenon caused by ice crystals, not the aurora.
• Option b: This describes a different kind of atmospheric optical phenomenon involving ice crystals, not the aurora.
• Option c: This accurately describes the process by which auroras are formed. The solar wind carries charged particles which interact with the Earth's magnetic field and are directed towards the poles, where they collide with atmospheric gases.
• Option d: This describes a sun dog, a bright spot alongside the Sun, which is different from Aurora.

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_ formulated the Theory of Relativity

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KPTCL Assistant Exam (Mescom) SLOT1 2017 click here to view all questions

________ formulated the Theory of Relativity.

AAlbert Einstein

BThomas Alva Edison

CCharles Darwin

DMichael Faraday

Nithin K ? Jul 31 '2017 at 20:0

Answer is : Albert Einstein

Explanation:

The general theory of relativity is the modern theory of gravitation, proposed in 1915, also by Albert Einstein. The central point of the theory is the principle of general relativity, which states that all observers, regardless of their state of motion, will see the same laws of physics operating in the universe.

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An electric charge in uniform motion produces

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RRB ASSISTANT LOCO PILOT (Allahabad) 2010 click here to view all questions

An electric charge in uniform motion produces

Aan electric field only

Ba magnetic field only

Cboth electric and magnetic field

DNone of these

prajwal ? Dec 24 '2019 at 10:2

Correct answer is: both electric and magnetic field

Explanation:

The electric charge is defined as an intrinsic fundamental quantity that is present in every matter that exists.

It produces:

• The electric field.
• The magnetic field.

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• Electric charge always has an influencing space around it that has an electric field defined at every point in three-dimensional space irrespective of the motion of the charge. So, either it is in motion or not in motion, always have an electric field around it.
• Whenever a charge is in motion, due to its speed, temporary magnetic space is created around it which is there only till the charge is in motion. So, charge in motion has magnetic fields around it.

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The line joining the north and south poles of a magnet is called

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RRB ASSISTANT LOCO PILOT (Allahabad) 2010 click here to view all questions

The line joining the north and south poles of a magnet is called

AMagnetic axis

BMagnetic Meridian

CMagnetic field

DNone of these

prakash ? Jan 2 '2020 at 12:16

Correct answer is: Magnetic axis

Explanation:

If the line joining NORTH and SOUTH POLE of a magnet or of the EARTH is a straight line. it is called AXIS (magnetic axis in magnetism).

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