Bihar Board 12th Physics Objective Important Questions Part 4
Bihar Board 12th Physics Objective Important Questions Part 4
Question 1.
Primary rainbow is formed due to:
(i) one reflection
(ii) one total internal reflection
(iii) one dispersion
(iv) all of these
Answer:
(ii) one total internal reflection
Question 2.
Velocity of light is C in vacuum. In the glass (µ = 1.5) it will be:
(i)
(ii)
(iii) C
(iv)
Answer:
(ii)
Question 3.
The velocity of light is maximum in:
(i) air
(ii) glass
(iii) water
(iv) vacuum
Answer:
(iv) vacuum
Question 4.
The speed of em wave in vaccum is equal to:
Answer:
(iv)
Question 5.
The velocity of light in a medium depends on:
(i) the intensity of the source
(ii) the frequency of the source
(iii) None of these
Answer:
(ii) the frequency of the source
Question 6.
Nature of light waves is:
(i) transverse
(ii) longitudinal
(iii) some times longitudinal some times transverse
(iv) None of these
Answer:
(i) transverse
Question 7.
Light waves are proved transverse by:
(i) interference
(ii) diffraction
(iii) polarisation
(iv) None
Answer:
(iii) polarisation
Question 8.
The vlocityof light in galss, whose refractive index µg = 1.5 is 2 × 108m/s. In certain liquid the velocity of light is found to be 2.6 × 108 m/s. The refractive index (µc)of the liquid is.
(i) 1.5
(ii) 1.2
(iii) 1
(iv) 2.1
Answer:
(ii) 1.2
Question 9.
Path difference in destructive interference is equal to:
(i) nλ
(ii) (n + 1)λ.
(iii) (2n + 1)λ
(iv) (2n + 1)
Answer:
(iv) (2n + 1)
Question 10.
Brewster’s law is:
(i) µ = sin ip
(ii) µ = cos ip
(iii) µ = sin ip
(iv) µ = tan2 ip
Answer:
(iii) µ = sin ip
Question 11.
Precious stones an detected with the help of
(i) ultraviolet rays
(ii) infrared rays
(iii) x-rays
(iv) None of the above
Answer:
(i) ultraviolet rays
Question 12.
Laser beam is:
(i) highly monochromatic
(ii) monochromatic
(iii) heterogeneous in nature
(iv) monochromatic or not depends upon the energy available
Answer:
(i) highly monochromatic
Question 13.
The laser is a source of:
(i) electric current
(ii) sound
(iii) incoherent light
(iv) coherent light
Answer:
(iv) coherent light
Question 14.
Electromagnetic waves are:
(i) longitudinal
(ii) compressional
(iii) transverse
(iv) both transverse and longitudinal
Answer:
(iii) transverse
Question 15.
X-rays or λ = 1A have freq. of:
(i) 3 × 108 Hz
(ii) 3 × 1018 Hz
(iii) 3 × 1010 Hz
(iv) 3 × 1015 Hz
Answer:
(ii) 3 × 1018 Hz
Question 16.
Cathode rays are:
(i) electrons
(ii) neutrons
(iii) protons
(iv) photons
Answer:
(i) electrons
Question 17.
The molecules of an atom consists of:
(i) protons
(ii) protons and electrons
(iii) protons and neutrons
(iv) α-particles
Answer:
(iii) protons and neutrons
Question 18.
Electron volt is:
(i) unit of charge
(ii) unit of potential difference
(iii) unit of current
(iv) unit of energy
Answer:
(iv) unit of energy
Question 19.
The charge of an electron is equal to:
(i) 1.6 × 10-1 C
(ii) 1.6 × 10-9 C
(iii) 1.6 × 10-19 C
(iv) 1.6 C
Answer:
(iii) 1.6 × 10-19 C
Question 20.
The size of the nucleus is of the order of:
(i) 10-13 cm
(ii) 10-23 cm
(iii) 10-8 cm
(iv) 10-10 cm
Answer:
(i) 10-13 cm
Question 21.
Which one of the following will deflect in electric field
(i) r-rays
(ii) x-rays
(iii) Uv rays
(iv) cathode rays
Answer:
(iv) cathode rays
Question 22.
Work function is the energy required:
(i) to excite the atom
(ii) just to eject electron form the surface
(iii) to produce x-rays
(iv) None of the above
Answer:
(ii) just to eject electron form the surface
Question 23.
Relation between mass and energy is:
(i) E = mc2
(ii) E = mc
(iii) E = mc3
(iv) None of these
Answer:
(i) E = mc2
Question 24.
Chadwick discovered:
(i) radioactivity
(ii) electron
(iii) proton
(iv) neutron
Answer:
(iv) neutron
Question 25.
β-particles are fast moving:
(i) electrons
(ii) positrons
(iii) protons
(iv) neutrons
Answer:
(i) electrons
Question 26.
γ-rays are similar to:
(i) α-rays
(ii) Cathode rays
(iii) X-rays
(iv) None of the above
Answer:
(iii) X-rays
Question 27.
According to maxwell’s hypothesis, a changing electric field gives rise to:
(i) an emf
(ii) Electric current
(iii) Pressure gradient
(iv) magnetic field
Answer:
(iv) magnetic field
Question 28.
The number of protons in an atom of atomic number Z and mass number A is:
(i) Z
(ii) A
(iii) A – Z
(iv) A + Z
Answer:
(i) Z
Question 30.
Phase diff. between electric and magnetic field in e.m. wave is:
(i) Zero
(ii) 90°
(iii) 120°
(iv) 180°
Answer:
(i) Zero
Question 31.
Which has higher frequency in e.m. spectrum?
(i) α-rays
(ii) β-rays
(iii) γ-rays
(iv) cathode rays
Answer:
(iii) γ-rays
Question 32.
Radio activity is associated with:
(i) fusion of nuclei
(ii) the decay of nuclei
(iii) the production of x-rays
(iv) thermionic emission
Answer:
(ii) the decay of nuclei
Question 33.
If T is the temperature of the filament, the thermionic current varies as:
(i) 7
(ii) T1/2
(iii) T2
(iv) T3
Answer:
(iii) T2
Question 34.
The energy of a photon of a wavelength is:
(i)
(ii)
(iii)
(iv)
Answer:
(iii)
Question 35.
The angluar momentum of an electron of mass m, charge erevolving in a circular orbit is L then its mag.movent is
(i) eLm
(ii)
(iii)
(iv)
Answer:
(iii)
Question 36.
The quantum of light is known as:
(i) photon
(ii) proton
(iii) hyperon
(iv) phonon
Answer:
(i) photon
Question 37.
A thermionic diode is used as:
(i) an amplifier
(ii) an oscillator
(iii) a modulator
(iv) a rectifier
Answer:
(iv) a rectifier
Question 38.
The action of a radio value is based on the principle of:
(i) thermionic emission
(ii) induction
(iii) Lenz’s law
(iv) Ohm’s law
Answer:
(i) thermionic emission
Question 39.
P-N Junction is used for:
(i) the measurement of temperature
(ii) converting A.C. into D.C.
(iii) obtaining higher voltage from low voltage
(iv) amplifying feeble currents.
Answer:
(ii) converting A.C. into D.C.
Question 40.
The number of photons of freq. 1014 Hz in radiation of 6.62 J will be
(i) 1010
(ii) 1015
(iii) 1020
(iv) 1025
Answer:
(iii) 1020
Question 41.
According to J.C.Bose, the range of wave length in e.m. wave is:
(i) 1 mm -10 mm
(ii) 25 mm – 50 mm
(iii) 200 mm – 500 mm
(iv) None of these
Answer:
(ii) 25 mm – 50 mm
Question 42.
Ozone layer is situated from the surface of earth:
(i) 40 km – 50 km
(ii) 100 km – 300 km
(iii) 500 km ~ 1000 km
(iv) None of them
Answer:
(i) 40 km – 50 km
Question 43.
Ionosphere is situated from the surface of earth:
(i) 50 km – 80 km
(ii) 200 km – 400 km
(iii) 500 km – 1000 km
(iv) None of them
Answer:
(ii) 200 km – 400 km
Question 44.
Boolean expression for NOR gate is
(i)
(ii)
(iii) A·B = y
(iv) A + B = y
Answer:
(ii)
Question 45.
The logic symbol
stands for
(i) OR-Gate
(ii) AND gate
(iii) NOR gate
(iv) NAND gate
Answer:
(iii) NOR gate
Question 46.
The height of TV transmission tower is 245 m at a place on the earth. The distance upto which the broadcasting can be send from the tower as-
(ii) 245 m
(i) 245 km
(iii) 50 km
(iv) 112 km
Answer:
(iii) 50 km
Question 47.
For TV Broadcast which type of modulation is used for audio signals?
(i) Amplitude modulation
(ii) Pulse modulation
(iii) Freq. modulation
(iv) None of these
Answer:
(iii) Freq. modulation
Matching Type Question – Answer
Question – Answer
Column-I – Column-II
1. William Gilbert → Electricity
2. Coulomb → Force between to electric charges
3. Karl F. Gauss → Gauss theorem
4. Benjamin Franklin → Kite experiment
5. Ven de Graff → Generator
6. Michael Faraday → Discovery of e.m. induction Law of electrolysis
→ Relation between light and magnetism
7. Joule → Law of heating effect
8. Tolman and Stewart → Experiment on Free electron of charge carriers
9. George simon ohm → Ohm’s law or Relation between current of p.d
10. Gustav Robert Kirchoff → Junction rule or Loop rule
11. Sir Charles F. Wheat stone → Thermo electricity
12. Thomas Johann seebeck → Thermo electricity
13. J.C.A Petties → Thermo electricity
14. Hans Christian Orested → Connection between electricity Magnetism
15. Jeans-Baptise Biot + Felix savart → Measurement of magnetic field due to current
16. Andre marie Ampere → unit of electric current
17. Fleming → Left hand rule and Diode valve
18. ‘D’Arsonoval → Galvanometer
19. Lawrence → Cyclotron
20. Nicola Tesla → Tesla (unit of magnetic field), ganerator or dynamo
21. Lenz → The direction of induced e.m.f. & current
22. Maxwell → Electrommagnetic wave
23. Hertz → Electron magnetic wave + unit of frequency
24. Christain Huygen → wave theory of light
25. Snell → Law of refraction
26. Galileo → Telescope
27. Newton → Telescope, surpascular theory of light
28. Thomas young → Interference of light
29. Fresnel → Diffraction of light
30. Fraunhofer → Diffraction of light & Dark line in visual spectrum
31. Willian Nicol → Nicol prism for producing plane polarised light
32. Sir David Brewster → Brewster’s law of relation between µ and ip
33. Rontgen → X-rays
34. J.J. Thomson → Electron, nature of cathode rays, mass spectrograph & experiment on electron diffraction
35. Ernest Rutherford → Nucleus, proton and Scattering of α – particle
36. Neil Bohr → Atom model, hydrogen atom.
37. Einstein → Photo electric equation, Theory of relativity.
38. Hallwachs → Photo electric effect.
39. Leonard → Law of photo electric effect.
40. Millikan → Law of photo electric effect.
41. Max Planck → Quantum theory of radiation.
42. Sir William Bragg → Wave length of X-rays
43. Sir Lawrence Bragg → Wave length of X-rays
44. Chadwick → Neutron
45. Heisenberg → Composition of Nuclei
46. Henry Becquerel → Radio activity
47. Piere Curie → Radium for radio activity
48. Madam Curie → Radium for radio activity
49. Soddy → Isotopes
50. Otto Hahn and strass man → Nuclear fission
51. John Wheelar → Theory of nuclear fission
52. De-Broglie → Matter waves or De-Broglie wave
53. Davisson & Germer → Experiment on wave nature of material particles
54. H.A.Bethe → Nuclear fusion on Sun.
55. Richardson → Explanation of therminoic emission
56. Edison → Thermionic emission or Edison effect
57. Coulomb → Force between two magnetic poles
58. Edwin Hall → Hall effect or potential difference developed in current and magnetic field.
59. Van Allen Belts → Magneto sphere
60. George Boole → Boolean Algebra.