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125 Physics Important Questions with Answers

125 Physics Important Questions with Answers


Physics Important Questions


Physics Important Questions with Answers Part 1

Questions 1-30


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?

Answer: Coulomb.


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?

Answer: Dalton.


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.


Physics University of Colorado


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?

Answer: Voltaire.


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?

Answer: Romer.


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

Questions 31-60


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”?

Answer: Galileo.


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?

Answer: 1771.


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?

Answer: 2n2.


44) What is the speed of an electron in the orbit of hydrogen atom in the ground state?

Answer: C/137.


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?

Answer: Green.


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

Questions 61-90


61) The momentum of a body depends on what?

Answer: Its mass and velocity.


62) What is the formula for potential energy?

Answer: mgh.


63) What is the co-efficient of restitution e for a perfectly, elastic collision?

Answer: 1.


64) What is the co-efficient of restitution e for a perfectly inelastic collision?

Answer: 0.


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?

Answer: w/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?

Answer: 4.


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?
Answer: Power.


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?
a. g
b. u
Answer: a.


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
Answer: a.


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
Answer: b.


88) The process of fusing and refreezing of ice is termed as _
Answer: Regelation.


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 _
Answer: Bel.


Physics Important Questions with Answers Part 4

Questions 91-125


91) What is the standard unit of dose?
Answer: Sievert.


92) Contrast image reproduction is measured as _
Answer: Gamma.


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?
Answer: Phosphorus.


97) How is the energy gap in a conductor?
Answer: Zero.


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?
Answer: Parabola.


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 _
Answer: Hole.


104) A petrol engine used to mix petrol and air in certain ratio for combustion, is called _
Answer: Carburettor.


105) What is the potential energy of an electron when it is far away from the nucleus?
Answer: Zero.


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 _
Answer: Tesla.


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 _
Answer: Poise.


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?
Answer: Admittance.


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?
Answer: Luminance.


120) Among the following, the unit of sound absorption is _
Answer: Sabin.


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.


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