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RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 2
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Que.1 What do you mean by science & write down its different branches?, Ans. The systematic and logical study of natural phenomenon and the laws, along with the knowledge gained by it, is called the science., Branches of science:1. Physics, 2. Chemistry, 3. Zoology, 4. Botany, 5. Astronomy, 6. Mathematics, , Que.2 What do you mean by physics & explain its parts?, Ans. Physics is the branch of science which deals with the study of nature and, its laws and natural phenomena is called physics., Physics consists of two parts:(a) Classical Physics and, , (b) Modern Physics, , (a) Classical Physics:- It consists of the following sub-topics., 1. Mechanics:- Mechanics deals with the study of general system of, particles, rigid bodies, deformable bodies, liquids etc, propulsion of, rockets, propagation of waves etc., 2. Thermodynamics:- Thermodynamics deals with changes in, temperature, internal energy and entropy of the system. Modes of transfer, of heat, efficiency of heat engines and refrigerators., 3. Electrodynamics:- Electrodynamics deals with the study of electric and, magnetic phenomena associated with charged particles and magnetic, materials., 4. Optics:- Optics deals with the study of phenomena associated with light, and optical instruments., (b) Modern Physics:- Modern physics deals with Quantum Theory. Quantum, Theory is the physics of particles of atomic size., , RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 3
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Que.3 What do you mean by scientific method. Explain the various steps, of scientific method?, Ans. Scientific method :- The method by which scientist studies science is, called scientific method., Following are the main steps of the scientific method :1. Systematic observation:- To find the solution of a problem, first the, scientist performs well planned experiments and collects data related to, that problem by taking systematic observation., 2. Formation of hypothesis:- To explain the data obtained from, experiments, then forms a self made working principle which is called the, hypothesis., 3. Testing the validity of hypothesis:- By the hypothesis some conclusions, are drawn and then some predictions are made which are then verified by, performing the new experiments., 4. Formation of principle:- The hypothesis is first tested by new, experiments. If it is valid then it is called a principle otherwise form a new, hypothesis., 5. Formation of law:- The principle is generally true only for some limited, phenomena, observations and facts. If it is true for all phenomena,, observations and facts then it is called law., , Que.4 What is the relation of physics to other branches of science?, Ans. For the study of any branch of science, it is essential to have the, knowledge of laws and principle of physics. i.e. , physics is treated to be the, base of other branches of science., Physics in relation to other branches of Science:(a) Physics in relation to Chemistry:• Chemical bonding, atomic number and complex structure can be explained, by physics phenomena of Electrostatic forces., • Taking help of X-ray diffraction., , RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 4
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(b) Physics in relation to Biological Sciences:Physics helps in study of Biology through its inventions. Optical microscope, helps to study bio-samples, electron microscope helps to study biological cells., X-rays have many applications in biological sciences. Radio isotopes are used, in cancer., (c) Physics in relation with Astronomy:Giant astronomical telescope developed in physics are used for observing, planets. Radio telescopes have enabled astronomers to observe distant limits, of universe., (d) Physics related to Mathematics:In physics, the mathematical operations are widely used. It is not possible to, understand the fundamental laws and principles of physics without the, knowledge of mathematics. Mathematics is the language of physics., , Que.5 State the universal law ?, Ans. The following five law of conservation are universal law:1. Law of conservation of mass:The law of conservation of mass states that the total amount of mass remains, constant in an isolated system in any physical or chemical changes that may, take place., , 2. Law of conservation of energy:The law of conservation of energy states that the total amount of energy, remains constant in an isolated system. It implies that energy can neither be, created nor destroyed, but can be change from one form to another., 3. Law of conservation of linear momentum:Law of conservation of linear momentum states that if no external force acts, on a system, the linear momentum of the system remains constant., , RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 5
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4. Law of Conservation of angular momentum:Law of conservation of angular momentum states that if no external torque, acts on a system, the angular momentum of the system remains constant., 5. Law of conservation of charge:The law of conservation of charge states that the total amount of electric, charge of an isolated or overall system does not change., , Que.6 Explain the different fundamental forces present in nature and, write down their properties?, Ans. There are four fundamental forces in nature:1. Gravitational Force, 2. Electromagnetic Force, 3. Strong Nuclear Force, 4. Weak Nuclear Force, (1) Gravitational Force:The gravitational force is a force of mutual attraction between any two objects, by virtue of their masses., It’s important properties are:1. They are universally attractive forces., 2. They are the weakest forces in nature., 3. They operate over long distances., 4. Gravitational Forces obey inverse square law (F α, , 1, ), r2, , 5. They are central forces as they act along the line joining the centre of two, bodies., 6. They are conservative forces., 7. The field particle (exchange of particle) of Gravitational force is graviton., 8. It does not depends on medium., , RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 6
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(2) Electromagnetic Force:Force acting between charged particles is called electromagnetic force. If, charge is stationary then force is called electrostatic force & if charge is, moving then force is called magnetic force., It’s important properties are:1. The forces may be attractive or repulsive., 2. Electromagnetic Forces are governed by Coulomb’s Law., 3. Obey Inverse square Law (F α, , 1, )., r2, , 4. They are 1036 times stronger than the gravitations forces and 1011 times, stronger than the weak nuclear force., 5. Operate over moderate distances., 6. Electromagnetic Forces are both conservative and central in nature., 7. The field particle (exchange of particle) of Electromagnetic force is photon., 8. It depends on medium., (3) Strong Nuclear Force:The forces that bind the neutrons and protons together in a nucleus are called, strong nuclear forces., It’s important properties are:1. Strongest forces in nature., 2. Short ranged force up to 10-15 meters., 3. Strong nuclear force does not depend on charge of the nucleon., 4. Do not obey inverse square law., 5. These forces are basically attractive forces, 6. These forces are non-central or non-conservative forces., 7. The field particle (exchange of particle) of Strong nuclear force is meson., (4) Weak Nuclear Force:The force between the elementary particles emitted during radio-active decay, of radio-active substance is known as weak nuclear forces., For example – In β-decay electron and a neutrino (uncharged particle) are, emitted. The force act b/w an electron and a neutrino is a weak nuclear force., It’s important properties are:1. It is a weak force but is 1025 times that of the gravitation force., 2. The range of weak nuclear force is of the order of 10 -16 meters., RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 7
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3. Do not obey inverse square law., 4. These forces are basically attractive forces, 5. These forces are non-central or non-conservative forces, 6. The field particle (exchange of particle) of Weak nuclear force is neutrino., , RISE PHYSICS CLASSES, , Er. Arvind Rawat Sir, , Mob:- 7000663196 , 7748045270, , Page 8
