SOLUTION

During hydrogen fusion, hydrogen nuclei or protons are smashed together to overcome columbic repulsive force. Strong nuclear force binds protons and neutrons in the nucleus to creates an unstable form of helium nucleus. After that the weak nuclear force acts inside of individual nucleons, to form a stable helium atom by radioactive decay process.

SOLUTION

James Chadwick studied the Rutherford’s scattering experiment and proposed the particles emitted in this experiment as neutron. He passed the same radiation though Berylliums and paraffin found that like gamma rays, these particles remain undeflected in magnetic field but unlike gamma rays neutrons do not eject electron from atom.

SOLUTION

Technology and physics, each one shares the development of the other. Technological tools and instruments made countless contributions for the discovery of scientific theories and laws. For example, the ancient humans developed technologies to survive in earth through different raw materials and tools. They didn't understand the science behind those things.

SOLUTION

According to law of conservation of mechanical energy for conservative forces, the sum of kinetic and potential energies at any point remains constant throughout the motion. The change in potential energy is equal and opposite to the change in kinetic energy.

SOLUTION

Two protons can attract as well as repel each other due to nuclear force. When protons are far apart, the electrostatic repulsive force dominates the nuclear force. It becomes very difficult to add protons to an atom.

SOLUTION

In a chemical reaction mass and energy are not conserved separately, but are conserved as a single entity called mass-energy. According to Einstein's famous equation for relativity, E = mc², mass can be transformed into energy and energy can be transformed into mass.

SOLUTION

The thermodynamic approach is applicable on macroscopic level. It deals with the temperature of the system, while the kinetic theory and statistical mechanics are applicable at microscopically level to describe the molecular movement in term of the average kinetic energy of its molecules.

SOLUTION

On macroscopic scale, individual particles of a gas can be related using ideal gas equation while on microscopic scale, kinetic theory of gas is used to study the property of individual particles.

SOLUTION

An optical microscope cannot resolve an object whose size is less than 6×10^-7 m. We use electron microscope to measure intermolecular distance in which an accelerated beam of electrons is focused by properly designed electric and magnetic field.

SOLUTION

\begin{array}{l}\text{Dimension of gravitational potential}\text{=}\frac{\text{Dimension}\text{of}\text{work}}{\text{Dimension}\text{of}\text{mass}}\\ \text{=}\frac{\left[{\text{ML}}^{\text{2}}{\text{T}}^{\text{-2}}\right]}{\left[\text{M}\right]}\text{=}\left[{\text{L}}^{\text{2}}{\text{T}}^{\text{-2}}\right]\\ \text{Dimension of latent heat}\text{=}\frac{\text{Dimension}\text{of}\text{heat}}{\text{Dimension}\text{of}\text{mass}}\\ \text{=}\frac{\left[{\text{ML}}^{\text{2}}{\text{T}}^{\text{-2}}\right]}{\left[\text{M}\right]}\text{=}\left[{\text{L}}^{\text{2}}{\text{T}}^{\text{-2}}\right]\end{array}

SOLUTION

The value obtained from the last measurement is closer to the actual length of the cloth.

SOLUTION

In a number less than one, zeros between the decimal point and non-zero digit are not significant. But zeros to the right of non-zero digit are significant.

SOLUTION

Tension is the force acting along the length of the solid object whereas surface tension is the tendency of the liquid and is equivalent to force per unit length for imaginary line drawn on free surface of liquid. So, dimensional formula for surface tension is [ML⁰T^-2] and dimensional formula for tension is [MLT^-2].

SOLUTION

SOLUTION

SOLUTION

Momentum = mass  velocity Dimensional formula is [M][LT^-1]

SOLUTION

The unit of power is kilowatt.

SOLUTION

Volume = Mass/density

SOLUTION

SOLUTION

Volume of a cube = a³ Surface area of a cube = 6a² ∴6a² = a³   ⇒ a = 6 unit ⇒ Volume of a cube = 216 cubic unit

SOLUTION

SOLUTION

SOLUTION

[ML^-1T^-2] stand for the dimensional formula of stress.[MT^-2] is the dimensional formula of surface tension,[M^-1L³T^-2] that of gravitational constant and [ML^-1T^-1] that of coefficient of viscosity.

SOLUTION

SOLUTION

Linear momentum , p = m  v.
[P] = [M][LT^-1] = [MLT^-1].

SOLUTION

One Pascal is equal to 1 newton/metre².

SOLUTION

In S.I. system, the unit of pressure is Pascal.

SOLUTION

SOLUTION

SOLUTION

SOLUTION

Angular momentum = Iω = [ML²][T^-1] = [ML²T^-1]

SOLUTION

SOLUTION

SOLUTION

SOLUTION

SOLUTION

  Dimension of work done = [ML²T^-2].
Dimension of potential energy = [ML²T^-2].  

SOLUTION

The shortest time interval is the time taken by the light to cross a distance of nuclear size in nearly 10^-22 seconds.

SOLUTION

The shortest distance measured indirectly so far is radius of proton, which is nearly 10^-15 m.

SOLUTION

watt = joule/second .
SI unit of energy can be written as wattsecond.    

SOLUTION

mass/length = M/L = [ML^-1]

SOLUTION

[F] = [MLT^-2] ; [V]=[L¹T^-1]
Given, F= Kv²
So, [MLT^-2] = K [LT^-1]² = K[L²T^-2]
[K]=[ML^-1]  

SOLUTION

F = a = [MLT^-2] F/x = b= [ML⁰T^-2]

SOLUTION

Power = Work/time = [ML²T^-2]/[T]                                = [ML²T^-3]

SOLUTION

The result of any physical quantity if expressed in various units then, it is n1/u.  

SOLUTION

1micron = 10^-6m. Level : knowledge.

SOLUTION

As 1 kg=10³ g and 1 mg =10^-3 g,we have 1kg=10⁶ mg.

SOLUTION

1 light year is the distance  travelled by light in vacuum in one year.
Velocity of light in vacuum = 3  10⁸ m/s.
1 year= (365  24  60  60) s. Distance = speed  time.
 1 light year = [(3  10⁸) m/s  (365  24  60  60) s]

SOLUTION

One mole is the amount of substance which contains as many elementary entities as there are atoms in 0.012 kg of carbon-12. A mole has Avagadro`s number of atoms or molecules of the pure substance being measured.

SOLUTION

Niels Bohr was born in Copenhagen, Denmark on 7th October 1885.

SOLUTION

Nuclear force have the shortest range. They operate upto distances of 10^-14 m.  10^-15 m = 1 fermi or 10^-14 m = 10 fermi  

SOLUTION

James Clark Maxwell gave electromagnetic theory, which states that light propagates in the form of electromagnetic waves.

SOLUTION

James Chadwick discovered neutron.

SOLUTION

Bardeen won the Nobel prize in 1956 for the discovery of transistor effect and in 1972 for the development of theory of superconductors known as BCS theory.

SOLUTION

The exchange particles for various forces are mentioned below. 1. Gravitational force  - gravitons 2. Weak nuclear force - weak bosons 3. Electromagnetic force - photons 4. Strong nuclear force - gluons

SOLUTION

Niels Bohr obtained the energy levels and spectral frequencies of the hydrogen atom in 1913.

SOLUTION

As classical physics deals with the particles with velocities much less than that of light, therefore it doesn't include the theory of relativity.

SOLUTION

Humidity is measured by hygrometer whereas a calorimeter is used to measure heat capacity.

SOLUTION

Mass of an electron = 9.11x 10^-31 kg Total mass = ½ kg Number of electron = =5.5x10²⁹

SOLUTION

Hideki' Yukawa made an attempt to explain the nature of nuclear forces in 1934.

SOLUTION

Force                                        Relative Strength Gravitational force                            1 Electromagnetic force                    10³⁶ Nuclear force                                    10³⁸

SOLUTION

In classical physics, we confine ourselves to the study of particles with size more than 10^-6 m, moving with velocities negligible with the speed of light. The size restriction excludes any appreciable effects of nuclear forces or weak forces. Therefore, we need to consider only the gravitational and electromagnetic forces.

SOLUTION

The relative strength of the four fundamental forces in nature are 1. Gravitational force = 1 2. Weak nuclear force = 10²⁵ 3. Electromagnetic force = 10³⁶ 4. Strong nuclear force = 10³⁸

SOLUTION

Photocell works on the principle of photoelectric effect which states that electrons are emitted when light radiations (photons) of suitable frequency fall on a metal surface.

SOLUTION

Electron was discovered by J.J.Thompson in the year 1897 as the particle radiated from cathode rays.

SOLUTION

As gravitational force varies inversely as r², so its range is infinite.

SOLUTION

Gravitational forces are central forces as they act along the line joining the centres of the two bodies.

SOLUTION

He was awarded Nobel Prize in Physics in 1983 for his studies on the physical processes important to the structure and evolution of stars.

SOLUTION

Optics is the branch of physics which deals with the study of nature, properties and various natural phenomena related to light.

SOLUTION

Charges in motion ( or electric current ) produce magnetic effects and a magnetic field gives rise to a force on a moving charge (electric effects). Electric and magnetic effects are, in general, inseparable – hence the name electromagnetic force.

SOLUTION

The gravitational force is the force of mutual attraction between any two objects by virtue of their masses. It is an universal force. Every object experiences this force due to every other object in the universe.

SOLUTION

Classical Physics deals mainly with macroscopic phenomena and includes subjects like Mechanics, Electrodynamics, Optics and Thermodynamics.

SOLUTION

Thermodynamics does not deal with the motion of bodies as a whole. But it may explain the movement of constituent particles inside a body and their heat energy. On the other hand, mechanics deals with the motion of bodies as a whole.

SOLUTION

Optics deals with the phenomena involving light. The vibrant colours exhibited by thin films of soap bubbles occur due to the interference of light rays. Therefore, it can be explained by Optics.

SOLUTION

Electrodynamics is the branch of physics that deals with electromagnetism or with electric and magnetic phenomena associated with charged and magnetic bodies. Radio waves are electromagnetic waves. So, the propagation of radio waves in the ionosphere is dealt in electrodynamics.

SOLUTION

There are two domains of interest: macroscopic and microscopic. The macroscopic domain includes phenomena at the laboratory, terrestrial and astronomical scales. The microscopic domain includes atomic, molecular and nuclear phenomena.

SOLUTION

There are two principal thrusts in physics used to understand the reasons and concepts behind the physical phenomena occurring in the nature. These two thrusts are - unification and reductionism.

SOLUTION

The wave picture of light failed to explain the photoelectric effect properly as photoelectric effect purely is based on the particle nature of light.

SOLUTION

When Johannes Kepler examined the extensive data on planetary motion collected by Tycho Brahe, he concluded that the planetary circular orbits in heliocentric theory (sun at the centre of the solar system) had to be replaced by elliptical orbits to fit the data better.

SOLUTION

Gravitational forces, F= Gm₁m₂/r² where m₁ and m₂ are masses of two different bodies and r is the distance between the two. From this, we can conclude that gravitational forces follow inverse square law. Every object in the universe experiences this force due to every other object.

SOLUTION

In heliocentric theory, the sun is imagined to be stationary and all the planets revolving around it. And geocentric theory imagines the earth to be at the centre of the universe.

SOLUTION

If an experiment is carried out today and is repeated after two years under the same conditions, we will get the same result. And the laws of physics are applicable in any part of the universe. Hence, the symmetry of nature with respect to translation (i.e. displacement) in time and space gives rise to the laws of conservation of energy and momentum, respectively.

SOLUTION

In  -decay, the energy and momentum are not conserved without the consideration of a particle and its antiparticle called neutrino and antineutrino respectively. This led to the prediction of the existence of such particles.

SOLUTION

Even though the laws of conservation of total linear momentum and the total angular momentum can be derived from Newton’s laws of motion in mechanics, but their validity goes beyond mechanics. They are the basic conservation laws of nature in all domains, even in those where Newton’s laws may not be valid.

SOLUTION

The general law of conservation of energy is true for all forces and for any kind of transformation between different forms of energy. The expressions for energy can be written for every physical system. When all forms of energy e.g., heat, mechanical energy, electrical energy etc., are counted, it turns out that energy is conserved. In short, the total energy of an isolated system is always conserved.

SOLUTION

The conserved quantities of nature should remain constant in time. Besides, total energy, total angular momentum and total linear momentum, quantities like charge, mass, spin, etc are also conserved in isolated systems.

SOLUTION

The range of weak nuclear force is smaller than that of the strong nuclear force (10^-15 m range). So, its range is of the order of 10^-16 m.

SOLUTION

The strong nuclear force is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron. Its range is, however, extremely small, of about nuclear dimensions (10^–15m).

SOLUTION

The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength.

SOLUTION

Action: The burnt fuel which appears in the form of hot and highly compressed gases escapes through the nozzle in backward direction. Reaction: The escaping gases push the rocket forward with the same force.

SOLUTION

The nuclear force between the nucleons exists only when they are inside the nucleus and hence, it is a short range force.

SOLUTION

Nuclear force is the strongest force operating in nature.

SOLUTION

The technologies in list A are based on one of the principles in list B. Technology Principle A Sonar (III) Reflection of ultrasonic waves B Aero plane (IV) Bernoulli’s theorem C Rocket propulsion (II) Newton’s second and third laws of motion D Electric Generator (I) Electromagnetic induction    

SOLUTION

The theory of electromagnetism deals with the study of electric and magnetic phenomenon. The theory of electromagnetic induction deals with the production of electromotive force across a conductor when it is placed in a time varying magnetic field. The theory of quantum mechanics deals with the microscopic domain. The theory of relativity deals with the particles moving with speed of the order of the velocity of light.

SOLUTION

Optics is the branch of physics that deals with the phenomenon of light.

SOLUTION

The forces operating inside the nucleus are called nuclear or strong forces. In general, the forces that are responsible for the interaction between mesons, between baryons and between baryons and mesons are called nuclear forces. Thus, nuclear force is due to the interaction between nucleons (baryons) and - mesons. The - mesons (^o, ⁺ and ^–) are the field particles for the nuclear forces.

SOLUTION

The process of -decay is due to weak interaction. In -decay, a neutron inside the nucleus changes into a proton by emitting an electron and an uncharged particle, called antineutrino  . The -decay may be represented as below:   During weak interaction, the two particles are in contact or exactly overlap each other.

SOLUTION

The force acting between two charges is given by Coulomb's law.
 

SOLUTION

Newton's law of gravitation is applicable to every body. Coulomb's law is applicable only to electrically charged bodies. Faraday's laws of electromagnetic conduction are applicable to conducting bodies placed in changing magnetic field. Hooke's law is applicable to bodies within elastic limits.  

SOLUTION

It was known by 1900 that the atom was not a simple, indivisible particle but contained at least one sub-atomic particle called electron which was identified by J.J. Thomson.

SOLUTION

Chandrasekhar proved that stars smaller than 1.44 times the solar mass end up as ‘White Dwarfs’. (Bigger ones explode as Supernova, and depending on their size, end up as neutron stars or Black Holes (in which the gravitational pull is so high that not even light can escape out of them).