MPTET Varg 1 Physics Mock Test - 3 - MPTET MCQ

नाक पर सुपारी तोड़ना' का भावार्थ है - बहुत परेशान करना
स्पष्टीकरण

• मुहावरा - नाक पर सुपारी तोड़ना'
• अर्थ - बहुत परेशान करना
• वाक्य प्रयोग -जब भी वह सोती है उसका छोटा भाई उसकी नाक पर सुपारी तोड़ता है।

अन्यसंबंधित बिंदु

• मुहावरा की परिभाषा - किसी भाषा की अभिव्यंजना के विशिष्ट रूप को मुहावरा कहते है यह वाक्यांश होते है।

सही उत्तर है - निर्मम

• जिसके ह्रदय में ममता न हो' के लिए उपयुक्त शब्द है 'निर्मम'।

स्पष्टीकरण

• निर्भय का अर्थ होता है भय-रहित।
• निर्दय का अर्थ अपने अत्याचारपूर्ण कृत्य से दूसरों को सताने वाला।
• निष्ठुर का अर्थ · क्रूर; बेरहम; निर्दय; हृदयहीन · कठिन; कठोर; सख्त; कड़ा

अतिरिक्त जानकारी
वाक्यांश के लिए एक शब्द:

• जब एक वाक्य का अर्थ देने के लिए किसी शब्द का प्रयोग हो तो उसे वाक्यांश के लिए एक शब्द कहते हैं।
• यह भाषा में प्रभाव पैदा करता है।

सही उत्तर है - वाला

• 'दुकानवाला' में प्रयुक्त प्रत्यय वाला है।

स्पष्टीकरण
प्रत्यय

• वह शब्दांश जिसे किसी भी शब्द के आखिरी में लगकर उसका अर्थ बदल देते हैं, ऐसे शब्दांश प्रत्यय कहलाते हैं।
• प्रत्यय के दो प्रकार होते हैं
• (1) कृत प्रत्यय और (2) तद्धित प्रत्यय।

अन्यसंबंधित बिंदु
उपसर्ग

• ऐसे शब्दांश जो किसी शब्द के पूर्व जुड़ कर उसके अर्थ में परिवर्तन कर देते हैं या
• उसके अर्थ में विशेषता ला देते हैं।
• उप + सर्ग का अर्थ है - किसी शब्द के समीप आ कर नया शब्द बनाना।

The correct answer is - "a"

Explanation

• From the given options, the most appropriate answer is "a".
• Indefinite Article "A" & "An" uses before singular countable nouns.
  • Example - A person, A woman, An MLA, etc.
• Article "A" can be used before collective noun (Countable).
• Here, Books is countable so Article "A" is used.
• Thus, Option 1 is correct option.

Other Related Points

• Definite Article "The" is used before things which are particular or specific plural nouns.
  • Example - The sun, The fort, etc.

The erroneous part is 'the workers gets'.

Explanation

• The given sentence is grammatically incorrect.
• Here, 'the workers get' should be used instead of 'the workers gets'.
• According to the “Subject-Verb Agreement Rule”, a singular subject always takes a singular verb and a plural subject always takes a plural verb.
• In the given sentence, ‘workers’ is a plural subject that will take ‘get’ as a plural verb.
• Thus, the correct answer is Option 4.
  

Correct Sentence: Every Saturday, the workers get their weekly wages.

The correct answer is Sikandar Lodī.
Explanation

• Sikandar Lodi (1489-1517 AD)​:
  • Modern Agra was founded by Sikandar Lodhi in the 16th century.
  • He shifted the capital from Delhi to Agra in 1506.
  • Babur, the founder of the Mughal dynasty, also stayed for some time in Agra and introduced the concept of square Persian-styled gardens here.
  • Emperor Akbar built the Agra fort and Fatehpur Sikri near Agra.​

Other Related Points

• Babur
  • He is the founder of the Mughal Empire.
  • He fought the first Battle of Panipat in 1526 with Ibrahim Lodhi and laid the foundation of the Mughal Empire.
  • His autobiography Tuzuk-i-Babri was written in the Turkish Language.
  • In 1527 his general Mir Baki built Babri Maszid.
  • He died in 1530.

• Akbar
  • He was born in 1542 at Amarkot.
  • He fought the second battle of Panipat in 1556 with Hemu and he defeated Hemu.
  • He abolished the religious tax Jizya.
  • He founded a new religion "Din-i- Allahi".
  • His biography was written by Abul Fazal " Ain-i-Akbari".
• Raja Bhoj
  • He was a famous scholar and poet of Sanskrit.
  • He ruled 'Dhar' from 1000 AD to 1055 AD.
  • He was a descendant of "Chakravarti Emperor Vikramaditya".
  • He was born in 980 AD in Ujjaini, the city of Maharaja Vikramaditya.
  • He made 'Dhar' his new capital in place of 'Ujjain'.​

The term inclusive means including or involving. It means involving all the children with disabilities, different castes, creeds, religions, and social, economic, or cultural backgrounds in one classroom. Inclusion celebrates the disability in a classroom. Many national policies and acts were launched which have spoken about inclusive education for all.

Explanation

• National Plan for Action for Children (2016)- Posits that all children and adolescents are entitled to education without being discriminated against for any physical or mental impairments.
• Rehabilitation Council of India Act (1992)- It talks about forming a national body for regulating the training and certification of professionals who will work with people with various physical and mental impairments.
• The National Trust Act (1999)- It is an Act that called for constituting a national body for looking after the welfare of people with intellectual disabilities, autism, cerebral palsy, etc. Its focus was to empower and skill people with disabilities to live independently and integrated into the community.
• District Primary Education Program (DPEP) was also a policy implemented in 1994 that attempted to reduce dropout rates of the schools in each district for students enrolled in primary classes and improve academic performance for all students, including students with disabilities.

Thus, it is concluded that all the above policies are related to Inclusive Education.

Concept:
Spherical mirrors

• The mirror with a curved reflecting surface is called a spherical mirror.
• The two types of spherical mirrors are concave and convex.
• Concave mirrors have reflecting surface curved inward and convex mirror as reflecting surface curved inward.
• Both types of mirrors can be observed in a spoon.
• The curved inward part of the spoon will act as a concave and the outward part will act as a convex lens.

Spherical Lens

• A lens is a transparent medium bounded by spherical surfaces.
• Usually, there are two types of lenses, concave and convex.
• The concave lens has both surfaces curved inward and the convex lens has both surfaces curved outward.
• A convex lens can be observed in a simple magnifying glass.

Explanation:

• The concave mirror can form a magnified image when the object is kept at a certain distance.
• A virtual, erect, and magnified image is formed when the object is placed very close (on focal length) to a concave mirror.
• This mirror is used by the dentist to get a magnified view of the teeth.
• On the other hand, the convex mirror gives a diminished image.
• A convex lens forms a virtual, erect, and enlarged image when the object is placed on its focal length.
• The concave lens forms a diminished image.

So, for magnification, a concave mirror or convex lens is used.
Important Point

• Real images are formed by the real intersection of light and are inverted.
• The virtual image is formed when the light intersection is apparent. Image formation by a plane mirror or convex mirror are always virtual.

Other Related Points

• The image formation by the concave mirror at different locations can be seen in the figure in the form of a ray diagram.
  
• The image formed by the convex lens can be seen in the below ray diagram.
  

Concept:
The self-inductance L of a solenoid of length l and area of cross-section A with a fixed number of turns N is

where μ₀ is the permeability of free space.
Solution:
→ L is directly proportional to A.
→ L is inversely proportional to l.
∴ L increases when A increases and l decreases.
The correct answer is option (2).

Concept:
Fluids:

• Fluid is any liquid or gas or any material that is unable to withstand a shearing or tangential force, when at rest.
• When the said forces are applied to the fluid, it goes through a continuous change in shape.
• Fluids are substances with zero shear moduli, i.e they cannot resist the shear force applied to them
• Air and water are examples of fluids.

Surface tension:

• Surface tension is the tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area.
• Surface tension not only depends upon the forces of attraction between the particles within the given liquid but also on the forces of attraction of solid, liquid, or gas in contact with it.
• The energy responsible for the phenomenon of surface tension may be thought of as approximately equivalent to the work or energy required to remove the surface layer of molecules in a unit area.
• Mathematically, Surface tension, s = F/L where, F = force, L = length
• The SI unit of surface tension is N/m.

Explanation:

• Surface tension is due to the cohesive force between water molecules.
• 
• This surface tension has a tendency to minimize the surface area by contracting surfaces by applying cohesive force.
• Thus, water tries to occupy smaller areas.
• The smallest possible area is in the shape of a sphere for a given volume.
• Therefore, raindrops are in spherical shape.

CONCEPT:
Electric dipole:

• When two equal and opposite charges are separated by a small distance then this combination of charges is called an electric dipole.
• The strength of an electric dipole is measured by a quantity known as a dipole moment i.e.

Where q = charge and 2a = distance between two charged particles

• The electric dipole moment is denoted by P and the SI unit of dipole moment is coulombmeter (Cm).

Potential energy:

• The potential energy of an electric dipole in an electric field E is the energy possessed by the dipole due to its particular position in the field.
• The expression of the potential energy of the dipole is

⇒ U = -pE (cosθ2 – cosθ1)
Where p = electric dipole moment, E = uniform electric field, θ₁ is the initial angle between the electric field and the dipole moment, θ₂ is the final angle between the electric field and the dipole moment


EXPLANATION:

• The electric potential energy of an electric dipole with dipole moment p in an external electric field E is

⇒ U = pE (cosθ2 – cosθ1)

• Assuming potential energy to be zero at θ₂ = π/2, cosθ₂ = 0

⇒ U = pE (– cosθ1) = - pE (cosθ1)

• If θ is the angle between the electric field and dipole moment and reference point where electric potential energy is considered to be zero is θ = π/2, then

⇒ U = - pE (cosθ)

• The negative sign indicates that the potential energy is negative at a stable position and positive at an unstable position.
• ​Therefore option 2 is correct

Other Related Points

• Force one a charge q in an electric field is defined as

⇒ F = Eq

• The work done by this force in moving the charge by a distance d along the direction of electrostatic force (along the electric field) is

⇒ W = F.d = Eq.d

• The work done by external force in moving this charge by a distance d along the direction of the electrostatic field is

⇒ Wext = - W = - Eq.d

• By definition, the change in potential energy in moving the charge in an electrostatic field is equal to the work done by external forces

• Electric potential is equal to the amount of work done per unit charge by an external force to move the charge q from infinity to a specific point in an electric field

• Therefore the relation between electric potential and electric potential energy is given by

• The net torque on the electric dipole is

• The net force on the dipole is zero.

From Newton's 2nd law of motion we have;
F_ext =
where Fext = external force acting on the object.
& P = momentum = mv
When there is no external force exists then, Fext = 0.
⇒ dP/dt = 0 ⇒ P = const. -----(1)
Calculation:
Given:
The total mass of the object = 5m,
Mass of two smaller fragments = m,
Mass of larger fragment = 5m - 2m = 3m,
The velocity of smaller fragments = v which are perpendicular.
Let us consider the velocity of 3rd fragment as V.
As there are no external forces acting on the object we can apply momentum conservation law as:
5m×u = mv î + mv ĵ + 3mV
⇒ 3mV = -mv(î + ĵ)
⇒ V = - (v/3) (î + ĵ)
⇒ IVI =
Energy will be released in the form of kinetic energy.
∴ The total energy released = (1/2)mv² + ​​(1/2)mv2 + (1/2)(3m)V2
= 4/3 mv2
Hence option (2) is the correct choice.

Binding energy of ²³⁵U nucleus = 235 × 7.2 = 1692 MeV
Binding energy of ¹¹⁶Pd nuclei = 2 × (116 × 8.2) = 1902.4 MeV
Energy of 2γ rays = 2 × 5.2 = 10.4 MeV
∴ Energy released (Q) = 1902.4 - (1692 + 10.4)
= 200 MeV

Concept:
LCR Circuit

• The ac circuit containing the capacitor, resistor, and inductor is called an LCR circuit.
• For a series LCR circuit, the total potential difference of the circuit is given by:

Where VR = potential difference across R, VL = potential difference across L and VC = potential difference across C

• For a series LCR circuit, Impedance (Z) of the circuit is given by:

Where R = resistance, XL = inductive reactance and XC = capacitive reactive

• The resonant frequency of a series LCR circuit is given by

Calculation:
Given,
Initial charge = C
Final charge = 5C
We know that resonant frequency,

As the frequency remain unchanged ν = ν^'
LC = L'C' = L' (5C)
L' = (L /5)

Concept:
When the object is thrown vertically upward and it reaches its maximum height then it returns back, the velocity keeps changing.
Because the body is not in uniform motion the slope of the displacement time graph never be a straight line so it must be the parabolic shape or parabolic curve.
Explanation:

Now the Body reaches its maximum height and returns back with the same path taking the same time because we know that it takes half of the time of total time for reaching the maximum height.
Here we can use the equation of motion in which the only condition is that the body should have constant acceleration.
So By the equation of motion, the displacement is given as:

As we can clearly see that the value of displacement relates to the time by square value hence the parabolic curve is achieved which is confirmed by the equation also.

CONCEPT:
The principle of superposition of waves:

• When two or more waves come together at some point in space then the resultant disturbance wave is the vector sum of disturbance of the individual waves.
  ​
• The principle of superposition is basic to the phenomenon of interference.
• Let us consider two harmonic travelling waves on a stretched string, both with the same ω (angular frequency) and k (wave number) and, therefore, the same wavelength λ. Their wave speed will be identical. Let us further assume that their amplitudes are equal and they are both travelling in the positive direction of the x-axis. The waves only differ in their initial phase.
• The two waves are described by the functions:

⇒ y₁ = a.sin(kx - ωt)
⇒ y₂ = a.sin(kx - ωt + ϕ)

• By the principle of superposition, the net displacement is given by,

• The resultant wave is also a harmonic travelling wave in the positive direction of the x-axis, with the same frequency and wavelength. However, its initial phase angle is .

Interference:

• When two waves superimpose then the resultant amplitude of the wave at that point is the vector sum of amplitudes of each individual wave. This phenomenon is called the interference of waves.
• There are two types of
  1. Constructive Interference:
  2. Destructive Interference:

EXPLANATION:

• If two waves superimpose with each other in the opposite phase, the amplitude of the resultant is equal to the difference in amplitude of individual waves, resulting in the minimum intensity of light, this is known as destructive interference.
• Hence, option 3 is correct.

Concept-

• The three basic single stage bipolar junction transistor which is used as a voltage amplifier is called CE amplifier.
• The input of CE amplifier is taken from the base terminal and the output is collected from the collector terminal.
• The emitter terminal is common for both the terminals in CE amplifier.

Explanation-

• In CE amplifier, the input is applied emitter-base junction with the forward biased.
• This amplify the signal.
• Thus the input ac signal to be amplified is applied across forward biased emitter-base junction. So option 1 is correct.

Concept:

• Stefan-Boltzmann law: It is given as the amount of radiation emitted per unit time from an area A of a black body at absolute temperature T is directly proportional to the fourth power of the temperature.

The Stefan-Boltzmann law:
E_b = σT⁴
where E_b is the emissive power of a blackbody, T is absolute temperature, and σ (= 5.67 X 10^-8 W/m²/K⁴) is the Stefan-Boltzmann constant.
Calculations:
Given that, T = 500 K
so, by Boltzman law
Eb αT⁴ = (500)⁴ K
Important Point

• A black body is an object that absorbs all the radiant energy reaching its surface.
• No actual body is perfectly black; the concept of a black body is an assumption with which the radiation properties of real bodies can be compared.

Properties of the black body:

• It absorbs all the incident radiation falling on it and does not transmit or reflect regardless of wavelength and direction
• It emits the maximum amount of thermal radiation at all wavelengths at any specified temperature
• It is a diffuser emitter (i.e. the radiation emitted by a black body is independent of direction)

CONCEPT:

• Rolling is a type of motion that combines pure rotatory motion and translation motion of that object with respect to a surface.
• The rolling motion of the has two simultaneous motions:
  • Pure Translational Motion
  • Pure Rotational Motion

EXPLANATION:

• Rolling motion can be regarded as the combination of pure rotation and pure translation.
• The wheel of all vehicles running on a road has a rolling motion. Consider a disc of radius R, rolling on a level surface without slipping. This means that at any instant of time the bottom of the disc which is in contact with the surface is at rest.​

Other Related Points

• Linear Motion is also known as rectilinear motion which is the tendency to move a body in a straight path, for example when a girl riding a cycle.
  .
• Circular Motion is the tendency to move a body in a circular path called circular motion, example of circular motion is:
  

The correct answer is Diverging lens.
Concept:

• Human eye: The organ due to which we can see the world is called the human eye.
• It consists of a convex lens/converging lens and the image by the human eye lens forms at the retina.

Explanation:
Myopia:

• A normal human eye can see any object from 25 cm to infinity.
• In myopia, the person cannot see far objects. The far point is less than infinity.
• Myopia can be caused by a longer-than-normal eyeball or by any condition that prevents light rays from focusing on the retina.
• This is corrected by a suitable concave lens.
• The concave lens (diverging lenses) diverges the ray of light such that the image of the far object can be formed on the retina.
  ​

Important Points

Concept:
Gravity:

• It's the force that attracts a body towards the center of the earth, or towards any other physical body having mass.

Air friction:

• Any mass object moving in air experiences a frictional force due to which its speed decreases with time.
  

Explanation:

• Any object that occupies mass experience gravity.
• Hence the moving bullet is under the force of gravity.
• As the bullet is moving, there will be a resistive force of air acting against the direction of movement.
• The resistance force of air is also called the frictional force.
• Hence the forces acting on a bullet moving toward the target are due to gravity and friction force.

Concept:
Velocity: The displacement per unit time is called velocity.

where v is the velocity, Δx is the change in displacement, Δt is the change in time.
A body comes to rest when the velocity is zero.
Calculation:
Given that position of a particle is given by: x = -2t2 + 4t
velocity

A body comes to rest when the velocity is zero.
v = -4t + 4 = 0
t = 1 sec
So the correct answer is option 2.

The correct answer is 0.28.
Explanation

• The resistance offered by the surfaces that are in contact with each other when they move over each other is called friction.
• Factors affecting friction:
  1. ​​Types of surfaces in contact.
  2. The normal force between the two surfaces.
• The friction force between any two surfaces is given as,

⇒ F = μN
Where F = friction force, μ = co-efficient of friction, N = normal reaction and m = mass of the body
Calculation:
Given P = 100 N and F = 28 N

From the diagram, it is clear that the applied force F will act as a normal force and for stopping a block against the wall, the developed friction force must be equal to the weight of the block.
So friction force is given as,
⇒ F = μN -----(1)
Also,
F = mg -----(2)
By diagram,
⇒ N = P -----(3)
By equation 1 equation 2 and equation 3,
⇒ μP = F

⇒ μ = 0.28

• Hence, option 2 is correct.

Concept:
Kepler’s laws of planetary motion:

• The law of Orbits: Every planet moves around the sun in an elliptical orbit with the sun at one of the foci.
• The law of Area: The line joining the sun to the planet sweeps out equal areas in equal intervals of time. i.e. areal velocity is constant.
• According to this law, the planet will move slowly when it is farthest from the sun and more rapidly when it is nearest to the sun. It is similar to the law of conservation of angular momentum.
• The law of periods: The square of the period of revolution (T) of any planet around the sun is directly proportional to the cube of the semi-major axis of the orbit i.e. T2 ∝ r3

​
Explanation:
Given

• By the law of periods, it is clear that,

-----(1)
By equation 1, for planet A and planet B,

• Hence, option 2 is correct.

Concept:

• Concave lens: It is a diverging lens that diverging the parallel beam of light.
  • It can also gather light from all directions and project it as a parallel beam.
  • The focal length of the concave lens is negative.
  • It has a virtual focus from the diverging rays of light that seem to converge.
• Convex lens: The lens whose refracting surface is upside is called a convex lens.
  • The convex lens is also called a converging lens.
  • The focal length of a convex lens is positive.

Explanation:

• The µ of the convex lens is greater than air so it will act as a convergent lens in the air.
• When it is dipped in water its µ is less than water. Now the rays entering and exiting the lens will bend toward or away from the normal in an opposite fashion than when the lens was placed in air.
• So the convergent lens in the air will now behave as a divergent lens in the water.

A biconvex lens when dipped in a medium denser than lens then it will behave as a diverging lens.

Concept:

• Displacement (S’): The minimum path length between starting point to final point is called displacement.

• Displacement is a vector quantity.
• It can be positive, negative or zero.
• The SI unit of displacement is meter (m).

Explanation:

• An object comes back to its starting point after travelling some distance then the displacement becomes zero.

So, average velocity = 0.

CONCEPT:
The force between two parallel currents:

• We know that there exists a magnetic field due to a conductor carrying a current.
• And an external magnetic field exerts a force on a current-carrying conductor.
• Therefore we can say that when two current-carrying conductors placed nearby each other will exert (magnetic) forces on each other.
• In the period 1820-25, Ampere studied the nature of this magnetic force and its dependence on the magnitude of the current, on the shape and size of the conductors, as well as, the distances between the conductors.
• Let two long parallel conductors a and b separated by a distance d and carrying (parallel) currents Ia and Ib respectively.
• The magnitude of the magnetic field intensity due to wire a, on the wire b is,
  
• The magnitude of the magnetic field intensity due to wire b, on the wire a is,
  
• The conductors 'a' and ‘b’ carrying a current Ia and Ib respectively will experience sideway forces due to magnetic field Bb and Ba respectively.

CALCULATION:
Given
If two current-carrying long wires A and B are separated by a very small distance and placed parallel to each other. Then the force per unit length on wire A and wire B is given as,
-----(1)
Where Ia = current in the wire A, Ib = current in the wire B, and d = distance between the wires
By equation 1 it is clear that whatever be the current in any wire, the force per unit length on both the wires will remain equal.

• So the ratio of the force per unit length on wire A to wire B will be,
  
• Hence, option 1 is correct.

Other Related Points

• The magnitude of the force on the segment L of the wire 'a' due to magnetic field Bb is given as,
  
• The magnitude of the force on the segment L of the wire 'b' due to magnetic field Ba is given as,
  

1. The magnitude of the force per unit length on wire a and wire b is given as,
   ​

Important Points

• When the current flows in the same direction in the two parallel wires then both wires attract each other and if the current flows in the opposite direction in the two parallel wires then both wires repel each other.

Concept:
The principle of superposition of waves:
y₁ = a∙sin (ωt), and y₁ = a∙cos (ωt)

• When two or more waves come together at some point in space then the resultant disturbance wave is the vector sum of disturbance of the individual waves.
  ​
• The principle of superposition is basic to the phenomenon of interference.
• Let us consider two harmonic travelling waves on a stretched string, both with the same ω (angular frequency) and k (wavenumber) and, therefore, the same wavelength λ.
  • Their wave speed will be identical. Let us further assume that their amplitudes are equal and they are both travelling in the positive direction of the x-axis. The waves only differ in their initial phase.
• The two waves are described by the functions:
  ⇒ y1 = a.sin(kx - ωt)
  ⇒ y2 = a.sin(kx - ωt + ϕ)
• By the principle of superposition, the net displacement is given by,
  
• The resultant wave is also a harmonic travelling wave in the positive direction of the x-axis, with the same frequency and wavelength. However, its initial phase angle is .

Calculation:
Given:

• The resultant amplitude of the wave after superposition of two waves:

⇒
Where, a = amplitude of wave 1, b = amplitude of wave 2, and ϕ = phase difference
Here, a = a, b = a and ϕ =
⇒
⇒
⇒

• Hence, option 1 is correct.

Additional InformationInterference:

• When two waves superimpose then the resultant amplitude of the wave at that point is the vector sum of amplitudes of each individual wave. This phenomenon is called the interference of waves.
• There are two types of
  1. Constructive Interference:
  2. Destructive Interference:

Radiation:

• Radiation differs from Conduction and Convection heat transfer mechanisms, in the sense that it does not require the presence of a material medium to occur.
• Energy transfer by radiation occurs at the speed of light and suffers no attenuation in a vacuum.
• Radiation can occur between two bodies separated by a medium colder than both bodies. It can heat any type of material whether it is solid or liquid or any gas.
• According to Maxwell's theory, energy transfer takes place via electromagnetic waves in radiation. Electromagnetic waves transport energy like other waves and travel at the speed of light.
• Thermal radiation emission is a direct result of the vibrational and rotational motions of molecules, atoms, and electrons of a substance. Temperature is a measure of these activities. Thus, the rate of thermal radiation emission increases with increasing temperature.
• Thermal radiation is a volumetric phenomenon. However, for opaque solids such as metals, radiation is considered to be a surface phenomenon, since the radiation emitted by the interior region never reaches the surface.

Concept and explanation:

• Rainbow is an arch of seven colors visible in the sky, which produced by the dispersion of sun’s light by raindrops in the atmosphere. Here, the Raindrops acts as a tiny prism in the formation of a rainbow.
• The process, which is involve in the formation of rainbow, is known as dispersion of light. After the dispersion of white light, Red, Orange, Yellow, Green, Blue, Indigo and Violet colors are formed.
• The formation of a rainbow involves a series of physical phenomena- reflection, refraction, dispersion and total internal reflection.

A rainbow can only form under the following conditions:

• The Sun must be above the horizon and not be obscured by clouds, mountains, or other obstacles.
• The Sun has to be quite low in the sky. If you are at the same elevation as your horizon, the Sun's altitude must be below 42° to create a rainbow that can be seen from your perspective.
• The air opposite the Sun, as seen from your position, must be filled with a large number of water droplets.
• Rainbows always appear in the sky opposite to the Sun. So, if you have your back to the Sun, the rainbow will arch across the sky in front of you.