1st PUC Physics Question Bank Chapter 1 Physical World

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Karnataka 1st PUC Physics Question Bank Chapter 1 Physical World

Question 1.
What is science?
Answer:
Science is a systematic attempt to understand natural phenomena in much detail, depth and use the knowledge so gained to predict, modify and control the phenomena.
Note: The word “science” comes from a Latin word “Scientia” and its meaning is “to know”.

Question 2.
Name the basic phenomenon involved in acquiring a scientific knowledge.
Answer:
Systematic study of natural phenomenon.

Question 3.
What is physics?
Answer:
Physics is the study of basic laws of nature and their manifestation in different natural phenomena.

Question 4.
Mention the several interconnected steps involved in scientific method.
Answer:
The scientific method involves systematic observations, controlled experiments, qualitative, quantitative reasoning, mathematical modeling, prediction and verification or falsification of theories.

Question 5.
There is no final theory in science and no unquestioned authority among scientists. Explain.
Answer:
The observation of the experiments may improve in detail and precision or the experiments may yield new results. The theory must account for this new observations or results by introducing modification. Sometimes the modification may be drastic also. Hence there is no final theory in science and no unquestioned authority among scientists.

Question 6.
Who introduced the concept of elliptical orbits for the motion of planets around the sun?
Answer:
Johannes Kepler.

Question 7.
What is the main drawback of Newtonian mechanics?
Answer:
Newtonian mechanics could not explain the atomic phenomena. ’

Question 8.
Mention the branch of physics which deals with atomic and molecular phenomena.
Answer:
Quantum mechanics.

Question 9.
What is the consequence of scattering of alpha particles by gold foil by Rutherford?
Answer:
It established the nuclear model of the atom.

Question 10.
Mention the experiment which leads to the basis for the quantum theory of hydrogen atom proposed by Niel Bohr.
Answer:
a-scattering experiment conducted by Rutherford.

Question 11.
Name the scientist who introduced the concept of antiparticle theoretically?
Answer:
Paul Dirac.

Question 12.
Name the scientist who confirmed the existence of antiparticle experimentally for the first time.
Answer:
Carl Anderson.

Question 13.
Name the first antiparticle to be discovered experimentally.
Answer:
Positron.

Question 14.
Name the antiparticle of electron.
Answer:
Positron.

Question 15.
Mention two principal thrusts in the study of physics.
Answer:
Unification and reductionism.

Question 16.
What is unification?
Answer:
Unification is an attempt to explain diverse physical phenomena interms of few concepts and laws

Question 17.
What is reductionism?
Answer:
Reductionism is an attempt to derive the properties of bigger, more complex system from the properties of its constituent simpler parts.

Question 18.
What are macroscopic and microscopic domains of physics?
Answer:
The macroscopic domain includes phenomena at the laboratory, terrestrial and astronomical scales.
The microscopic domain includes atomic, molecular and nuclear phenomena.

Question 19.
What is classical physics?
Answer:
Classical physics deals with macroscopic phenomena and includes subjects like mechanics, electrodynamics optics and thermodynamics.

Question 20.
What do you study in modern physics?
Answer:
Modem physics deals with the phenomena associated with microscopic particles.

Question 21.
What is mechanics?
Answer:
Mechanics is based on Ne wton’s law of motion and law of gravitation. It deals with motion or equilibrium of particles, rigid and deformable bodies, general system of particles, propulsion of rocket by jet of ejecting gases, propagation of water or sound waves, equilibrium of bent rod under a load etc.

Question 22.
What is electrodynamics?
Answer:
Electrodynamics deals with electric and magnetic bodies associated with charged and magnetic bodies.

Question 23.
Name the scientists who gave the basic laws of electrodynamics?
Answer:
The basic laws of electrodynamics were given by coulomb, Oersted, Ampere and Faraday.

Question 24.
What is optics?
Answer:
Optics deals with phenomena involving light. It also deals with telescopes, microscopes and also colours exhibited by thin films. OR The science of light is known as optics.

Question 25.
Mention the name of the scientist who introduced the concept of antiparticle theoretically.
Answer:
Paul Dirac

Question 26.
Name the scientist who discovered positron.
Answer:
Carl Anderson

Question 27.
What is thermodynamics?
Answer:
Thermodynamics deals with systems in macroscopic equilibrium and changes in internal energy, temperature, entropy of the system through external work and transfer of heat. It also deals with efficiency of heat engines, refrigerators, the direction of physical or chemical process.

Question 28.
Mention the range of magnitude lengths used measurement of a physical quantity.
Answer:
It involves the measurement of very small length 10^-14 m involving electrons, protons etc. It also deals with size of the galaxies or entire universe which is about 10²⁶ m.
∴ \(\frac{10^{-26}}{10^{-14}}=10^{40}\)

Question 29.
A stone and a feather are made to fall from the same height. Do they reach the ground at the same instant of time in the (a) presence of atmosphere (b) absence of atmosphere and why?
Answer:
(a) No, air resistance is not same. Hence they do not reach the ground simultaneously.
(b) Yes, there is no air resistance. Hence both stone and feather reach the ground together.

Question 30.
Is the acceleration due to gravity depends on the mass of the object?
Answer:
The acceleration due to gravity does not depends on the mass of the object.

Question 31.
Give few examples for “physics generates new technology”.
Answer:

1. The wireless communication technology followed by discovery of basic laws of electricity and magnetism.
2. The technology of silicon chip base on semi-conductor lead to the revolution of computer revolution.
3. The technology of conversion of solar energy into electricity based on photoelectric effect.

Question 32.
What is technology? Give some link between technology and physics.
Answer:
Technology deals with the application of science.

 

Technology	Technology Scientific principle (s)
1. Steam engine	Laws of thermodynamics.
2. Nuclear reactor	Controlled nuclear fission.
3. Radio and Television	Generation, propagation and detection of electromagnetic waves.
4. Computers	Digital logic.
5. Lasers	Light amplification by stimulated emission of radiation.
6. Production of ultra high magnetic fields.	Superconductivity.
7. Rocket propulsion.	Newton’s laws of motion.
8. Electric generator	Faraday’s laws of electromagnetic induction.
9. Hydroelectric power	Conversion of gravitational potential energy into electrical energy.
10. Aeroplane	Bernoulli’s principle in fluid dynamics.
11. Particle accelerators	Motion of charged particles in electromagnetic fields.
12. Sonar	Reflection of ultrasonic waves.
13. Optical fibres	Total internal reflection of light.
14. Non – reflecting coatings	Thin film optical interference.
15. Electron microscope	Wave nature of electrons.
16. Photocell	Photoelectric effect
17. Fusion test reactor (Tokamak)	Magnetic confinement of plasma.
18. Giant Micriwave Radio Telescope (GMRT).	Detection of cosmic radio waves.
19. Bose-Einstein condensate	Trapping and cooling of atoms by laser beams and magnetic fields.

Question 33.
Name the scientist. Who gave the principle of buoyancy?
Answer:
Archimedes.

Question 34.
Name the scientist who proposed the wave theory of light.
Answer:
Christian Huygen.

Question 35.
Name the scientist who formulated the universal law of gravitation.
Answer: Isaac Newton.

Question 36.
Mention the name of the scientist who showed that light is an electromagnetic wave.
Answer:
James Clerk Maxwel.

Question 37.
Name the scientist who gave the laws of electromagnetic induction.
Answer:
Michael Faraday.

Question 38.
Name the Indian scientist who discovered ultra short, radio waves.
Answer:
J.B. Bose.

Question 39.
Who discovered electron?
Answer:
J.J. Thomson

Question 40.
Who discovered X-rays?
Answer:
W.K. Roentgen.

Question 41.
What is the contribution of Marie Curie in the field of Physics?
Answer:
She discovered radium and polonium. Further she discovered the phenomenon of natural radioactivity.

Question 42.
Who discovered phenomenon of neutron induced fission of Uranium?
Answer:
Hahn and Meitner.

Question 43.
What is the principle behind nuclear power reactor and nuclear weapon?
Answer:
Neutron induced fission reaction.

Question 44.
Who proposed the nuclear model of atom?
Answer:
Ernest Rutherford.

Question 45.
Name the first Indian scientist to get the Nobel prize.
Answer:
Sri C.V. Raman

Question 46.
What is the contribution of Sir. C.V. Raman in the field of Physics?
Answer:
Sir C.V. Raman discovered Raman effect which deals with scattering of light.

Question 47.
What is Raman effect?
Answer:
Raman effect deals with scattering of light by molecules of a medium when they are excited to vibrational energy level.

Question 48.
Name the scientific principle behind the technology of steam engine. i Answer: Laws of thermodynamics.

Question 49.
Mention the scientific principle behind the technology of Lasers.
Answer:
Light amplification by stimulated emission of radiation.

Question 50.
Mention the scientific principle behind the technology of Rocket propulsion.
Answer:
Newton’s law of motion.

Question 51.
Name the scientific principle behind the technology of optical fibres.
Answer:
Total internal reflection.

Question 52.
Mention the scientific principle behind the technology of electron microscope.
Answer:
Wave nature of electrons.

Fundamental Forces in Physics

Question 1.
Name the fundamental forces in nature.
Answer:

1. Gravitational force
2. Electromagnetic force
3. Weak nuclear force
4. Strong nuclear force

Question 2.
What is gravitational force?
Answer:
It is the force of mutual attraction between any two objects by virtue of their masses.

Question 3.
Name the force which governs the motion of planets around the sun.
Answer:
Gravitation force between the planet and the sun.

Question 4.
Does the gravitational force need any intervening medium between two bodies?
Answer:
No, it does not require any medium between two bodies.

Question 5.
Name the weakest fundamental force in nature.
Answer:
Gravitational force.

Question 6.
Is the law of gravitation valid on the surface of the moon?
Answer:
Yes it is valid on the surface of the moon.

Question 7.
What is electromagnetic force?
Answer:
It is the force between two charged particles.

Question 8.
What is the nature of the force that exists between two
(i) like charges
(ii) unlike charges.
Answer:
(i) repulsive force
(ii) attractive force

Question 9.
Distinguish between gravitational force and electromagnetic force.
Answer:

Gravitational force	Electromagnetic force
1. It is the force of attraction between two objects by virtue of their masses.	1. It is the force between two charged particles.
2. It is always attractive.	2. It is either attractive or repulsive

Question 10.
Compare the magnitude of gravitational force and electromagnetic force between two protons separated
by the same distances.
Answer:

∴ electromagnetic force is 10³⁶ time stronger than gravitational force

Question 11.
Name the fundamental force which dominates the phenomena at atomic and molecular scales.
Answer:
Electromagnetic force.

Question 12.
What is strong nuclear force?
Answer:
It is the force which binds protons and neutrons in a nucleus.

Question 13.
Name the strongest of all the fundamental forces.
Answer:
Nuclear force.

Question 14.
What is the ratio of magnitude of nuclear force to the electromagnetic force?
Answer:
If F_N nuclear force between two protons separated by certain distance and Fe is the electromagnetic force
between same two protons separated by the same distance then
\(\frac{F_{N}}{F_{e}}=\frac{10^{2}}{1}=100\)
i.e., nuclear force is 100 time stronger than electromagnetic force.

Question 15.
Is the nuclear force is charge dependent force?
Answer:
No, nuclear force is a charge independent force. The force between two protons (F_pp) or two neutrons (F_nn) or a proton and a neutron (F_pn) is same.
i.e., F_pp = F_nn= F_pn

Question 16.
What is the range of the nuclear force?
Answer:
The nuclear forces acts over a small distance i.e., about nuclear dimensions 10^-15 m.

Question 17.
Name the fundamental force responsible for the stability of the nuclei.
Answer:
Strong nuclear force.

Question 18.
What are quarks?
Answer:
The atomic and sub-atomic particles are made of more elementary particles called quarks.

Question 19.
What is weak nuclear force?
Answer:
It is the force that appears only in certain nuclear process such as P-decay of a nucleus.

Question 20.
Name the uncharged particle emitted during P-decay.
Answer:
Neutrino.

Question 21.
What is the range of weak nuclear force?
Answer:
The range of the weak nuclear force is exceedingly small i.e., it is of the order of 10^-16m.

Question 22.
Name the scientist who unified terrestrial and celestial domains under common law of gravitation. Answer: Newton.

Question 23.
Name the scientists who showed that electric and magnetic phenomena are inseperable.
Answer:
Oersted and Faraday.

Question 24.
Name the scientist who unified electromagnetism and optics.
Answer:
Maxwel.

Question 25.
What are conserved quantities?
Answer:
The quantities which remain constant with time are called conserved quantities.

Question 26.
Mention few quantities which are conserved.
Answer:
Total energy of the system, linear momentum, angular momentum charge etc.

Question 28.
Name the scientist who predicted the existence of neutrino emitted during P-decay.
Answer:
Wolfgang Pauli

Question 29.
Do the laws of nature change with time?
Answer:
No, the laws of nature do not change with time.

Question 30.
Give some major contributions to physics from physicists from different countries of the world.
Answer:

Name	Major contribution
1. Archimedes	Principle of buoyancy; Principle of the lever
2. Galileo Galilei	Law of inertia
3. Christiaan Huygens	Wave theory of light
4. Isaac Newton	Universal law of gravitation; Laws of motion; Reflecting telescope
5. Michael Faraday	Laws of electromagnetic induction
6. James Clerk Maxwell	Electromagnetic theory: Light -an electromagnetic wave .
7. Heinrich Rudolf Hertz	Generation of electromagnetic waves
8. J.C. Bose	Ultra short radio waves
9. W.K. Roentgen	X-rays
10. J.J. Thomson	Electron
11. Marie Sklodowska Curie	Discovery of radium and polonium; Studies on natural radioactivity
12. Albert Einstein	Explanation of photoelectric effect: Theory of relativity
13. Victor Francis Hess	Cosmic radiation
14. R.A. Millikan	Measurement of electronic charge
15. Ernest Rutherford	Nuclear model of atom
16. Niels Bohr	Quantum model of hydrogen atom
17. C.V. Raman	Inelastic scattering of light of molecules
18. Louis Victor de Broglie	Wave nature of matter
19. M.N. Saha	Thermal ionisation
20. S.N. Bose	Quatum statistics
21. Wolfgang Pauli	Exclusion principle
22: Paul Dirac	Relativistic theory of electron; Quantum statistics
33. Edwin Hubble	Expanding universe
24. Ernest Orlando Lawrence	Cyclotron
25. James Chadwick	Neutron
26. Hideki Yukawa	Theory of nuclear ‘forces
27. Homi Jehangir Bhabha	Cascade process of cosmic radiation
28. Lev Davidovich Landau	Theory of condensed matter; Liquid helium
29. S. Chandrasekhar	Chandrasekhar limit, structure and evolution of stars
30. John Bardeen Transistors;	Theory of super conductivity
31. C.H. Townes	Maser; Laser
32. Abdus Salam	Unification of weak and electromagnetic interactions