125 Physics Important Questions with Answers
Physics Important Questions with Answers Part 1
1) Who invented electric bulb?
Answer: Thomas Alva Edison.
2) Who first made an electro magnet?
Answer: William Sturgeon.
3) Who discovered that the flow of electric current influences a magnetic needle?
Answer: Oersted – in 1820.
4) Who determined the quantity of electric charge in an electron?
Answer: Robert Andrews Millikan.
5) Who developed the law of attraction or repulsion of electric charges?
6) Who artificially made radio isotopes?
Answer: Irene curie, Frederic Joliot.
7) Who 1st predicted the existence of Isotopes?
Answer: Frederick Soddy.
8) Who discovered the existence of the nucleus inside the atom?
Answer: Ernest Rutherford -in 1911.
9) Who is the enunciator of modem atomic theory?
Answer: John Dalton.
10) Who made the first nuclear reactor?
Answer: Enrico Fermi.
11) Who is the father of the concept of atom?
12) Who first used the word ‘electric’?
Answer: William Gilbert.
13) Who proved the existence of seven colors in sunlight?
Answer: Sir. Isaac Newton.
14) Who proved that light travels faster than sound?
Answer: Ole Romer.
15) Who first made artificial dye from coal tar?
Answer: W.H. Perkin.
16) Which instrument is used to demonstrate Archimedes principle?
Answer: Cartesian diver.
17) When was nuclear fission discovered?
Answer: In 1938 by Lise Meitner (Austria) and Otto Hahn (Germany).
18) Who tried to prove that air is weightless?
19) Who was the Indian scientist awarded Nobel – prize for physics?
Answer: Dr. C.V. Raman, in 1930.
20) Who invented Radar?
Answer: Albert H. Taylor.
21) Who propounded the theory of electrolysis?
Answer: Michael Faraday.
22) Who first measured the velocity of light?
23) Who invented Calculating Machine?
Answer: Wilhelm Schickard.
24) Who discovered Airplane?
Answer: Wilbur and Orville Wright
25) Who invented Airship?
Answer: Ferdinand von Zeppelin.
26) Who was the first to suggest this idea “Radiant energy can be emitted and absorbed by atoms only in discrete amounts called ‘quanta’ ”?
Answer: Max Planck.
27) Who first contemplated “the speed of light is the same no matter how it is measured”?
Answer: Albert Einstein.
28) Who was the first to suggest that matter and energy are inter changeable?
Answer: Albert Einstein.
29) Who first formulated the idea that ‘a moving rod contracts in the direction of its motion’?
Answer: Lorentz and Fitzgerald independently.
30) Who first proposed the concept of atomic number?
Answer: Henry Moseley.
Physics Important Questions with Answers Part 2
31) Who, in 1829, was the first scientist to suggest that the spectral line should be used as a standard of length?
Answer: Jacques Babinet.
32) Who formulated the idea ‘the farther away a galaxy is, the faster it is moving’?
Answer: Edwin Hubble.
33) Who gave the idea, “the light in proceeding from point to point travels along the route which minimizes file time required”?
Answer: Pierre de Fermat.
34) Who was the first to think, “The period of oscillation of a pendulum is independent of its amplitude”?
35) Who was the first to give the idea, “Each pure substance has its own characteristic spectrum”?
Answer: Gustav Kirchhoff.
36) Who was first to think about “A pivoted magnetic needle placed parallel to a wire carrying an electric current makes oscillation”?
Answer: Hans Christian Oersted.
37) Who was first to suggest “A planet moves most quickly when it is closest to the sun, but slows down as it moves farther away”?
Answer: Johannes Kepler.
38) “Regular strokes of the pendulum could be utilized in the accurate measurement of time”
Who was the first to advance this idea?
Answer: Galileo Galilee.
39) 8 Nov. 1895 is an important date in the history of physics. What is it?
Answer: Roentgen discovered the X-rays.
40) In 1752, Benjamin Franklin conducted the famous kite experiment. What did it suggest?
Answer: Lightning is a form of electricity.
41) In which year did Luigi Galvani discover, albeit accidently, the action of electricity on the muscles of a dissected frog?
42) What is the important event which took place in 1665?
Answer: The discovery of Newtonian laws of gravitation.
43) For given value of n, what is the maximum number of electrons in an orbit?
44) What is the speed of an electron in the orbit of hydrogen atom in the ground state?
45) Which is the best laboratory approximation to an ideal black body?
Answer: A hollow enclosure blackened inside with soot and having a small hole.
46) From where fraunhofer, lines are observed in the spectrum?
Answer: The sun.
47) Why is the fraunhofer lines present in the spectrum?
Answer: Vapors of elements present in atmosphere absorb certain colors.
48) Write an example of sources that give discrete emission spectrum:
Answer: Mercury Vapor lamp.
49) Which is the longest wavelength?
Answer: Infra-red radiation.
50) Light from a distant star is examined with a spectroscope. What does the spectrum show?
Answer: Temperature of star.
51) From where Band spectrum is obtained?
Answer: Molecules In the gaseous state of matter.
52) Which type of spectra is produced in a candle flame, an electric bulb and a kerosene oil lamp?
Answer: Continuous spectra.
53) In which color, wavelength of 5450 A0 occurs?
54) What is the velocity of an electron in ground state?
Answer: 2 x 106m/s.
55) The energy of an electron in the first orbit of hydrogen atom is -13.6 ev. What is the energy of the electron in the fourth orbit?
Answer: -0.85 ev.
56) Name an object which has no potential, energy but has only kinetic energy:
Answer: A running vehicle.
57) What do you mean by a potential energy?
Answer: Potential energy is the stored energy.
58) What is the escape velocity from the moon?
Answer: 2.37 km/s.
59) Which is the direction of rotation of a synchronous satellite of earth?
Answer: West to east.
60) Which force is needed to change the direction of a moving body?
Answer: External unbalanced.
Physics Important Questions with Answers Part 3
61) The momentum of a body depends on what?
Answer: Its mass and velocity.
62) What is the formula for potential energy?
63) What is the co-efficient of restitution e for a perfectly, elastic collision?
64) What is the co-efficient of restitution e for a perfectly inelastic collision?
65) How many times is the energy increased if the unit of force and length be each increased by four times?
Answer: 16 times.
66) What is the mechanical advantage in a machine where a resistance W is overcome by applying an effort p?
67) How much work a man does when he pushes a wall and fails to displace it?
Answer: No work at all.
68) Why does an athlete run some distance before taking a long jump?
Answer: By running the athlete gives himself larger inertia of motion.
69) Which force done by the system will increase the potential energy of the system?
Answer: A conservative force.
70) Two particles of masses 1 g and 4 g are moving with equal linear momenta. What is the ratio of their kinetic energies?
71) When do the period of oscillation gets doubled in a simple pendulum?
Answer: The length is made four times.
72) An increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy is a principle named as?
Answer: Bernoulli’s theorem.
73) In a constant temperature process the product of pressure and volume is constant, what is this law called?
Answer: Boyle’s law.
74) Dimensional expression ML2T-3 is of which physical quantity?
75) The first Asian to win noble prize in the science, for his work on scattering of light?
Answer: C.V Raman.
76) The energy lost as heat, in reversing the magnetization of the material is?
Answer: Hysteresis loss.
77) An electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave can be termed as what?
Answer: Electronic Oscillator.
78) Flow of liquid through a pipeline can be related with what?
Answer: Reynolds Number (Re).
79) Among the following, how is shear modulus denoted?
80) When a bullet rises vertically upward, what is the change that happens to its kinetic energy ?
Answer: It decreases.
81) What are the factors affecting the rate at which the energy radiated by a body?
Answer: All the above factors.
82) What is the range of gravitational potential energy of the universe?
Answer: 1068 J.
83) The energy is having a dimensional formula as _
Answer: ML2 T-2.
84) For what measurement is the ‘Becquerel’ used?
Answer: Activity of a radionuclide.
85) The Theory of Relativity was proposed by whom?
a. Albert Einstein
b. Albert A.Michelson
86) The area swept by the planet’s orbital radius in equal intervals of time is equal, is stated in which law?
Answer: Kepler’s Law of period.
87) Which among the following is an example of speed of a longitudinal wave?
a. Light wave.
b. Sound wave
88) The process of fusing and refreezing of ice is termed as _
89) The middleweight particles were named as ‘meson’, by whom?
Answer: Homi J. Bhabha.
90) A measure of comparative power ratio or relative loudness is called as _
Physics Important Questions with Answers Part 4
91) What is the standard unit of dose?
92) Contrast image reproduction is measured as _
93) The idea of Principia written by Isaac Newton was formed with the support of which person?
Answer: Edmund Halley.
94) The amount of energy required to raise temperature by one unit (1°C), is termed as _
Answer: Specific heat capacity.
95) What was the subject ‘physics’ called in earlier times?
Answer: Natural Philosophy.
96) Name any one element, other than ‘As’ and ‘Sb’, which can be used as impurity with germanium to form n-type semiconductor?
97) How is the energy gap in a conductor?
98) The optical science was first described by whom in the early ages?
Answer: Robert Grosseteste.
99) An Italian philosopher who said that ‘the sun might be an ordinary star’ was burnt to death, name it?
Answer: Giordano Bruno.
100) The kinetic energy v/s speed graph is in which shape?
101) The minimum amount of energy required to remove the most loosely bonded electron is called as?
Answer: Ionisation energy.
102) When does the value of energy becomes zero for an electron?
Answer: Far away from the nucleus.
103) The vacant space of a solid’s, electronic energy level is _
104) A petrol engine used to mix petrol and air in certain ratio for combustion, is called _
105) What is the potential energy of an electron when it is far away from the nucleus?
106) The book Hydrodynamic containing the explanation of Bernoulli’s theorem was published by whom in the year 1738?
Answer: Daniel Bernoulli.
107) What is the energy equivalent of the mass of an electron?
Answer: Mass of an electron = 0.0511 eV.
108) Name the scientist who first proposed the wave theory of light?
Answer: Christian Huygens.
109) Acceleration due to gravity measured in Gal is equal to _
Answer: 1 cm/s2.
110) A barn of nuclei is equal to _
Answer: 10-24 cm2.
111) Magnetic flux density is measured in _
112) How is the mass of an electron get converted to energy?
Answer: Combining it with a positron.
113) What is the term used to refer the exchange of energy between a particle and an electromagnetic wave?
Answer: Radiation heat.
114) The unit of Viscosity in the CGS system is _
115) Around the nucleus, surrounds the electron with a total energy _
Answer: Less than zero.
116) 1022J of energy can be related equal to which among the following?
Answer: Solar energy received per day on the earth.
117) What is the reciprocal of the impedance of an electric current?
118) Why is 8th November 1895 regarded as special day of physics?
Answer: W. Roentgen discovered X-rays.
119) The unit ‘Nit’ is used in what?
120) Among the following, the unit of sound absorption is _
121) 2 December 1942 is known for:
Answer: The creation of the first controlled chain reaction.
122) The Standard Unit of measurement of magnetic field strength is _
Answer: Ampère per metre.
123) An engine develops 10 kw of power. How much time will it take to lift a mass of 200 kg to height of 40 meter (g = 10 ms2)
Answer: 8 sec.
124) What is called the energy, which an electron acquires when accelerated through a potential difference of 1 voit?
Answer: 1 e v.
125) What is called the perpendicular distance from effort to fulcrum?
Answer: Effort arm.