Hot 2019 Key Points In Physics Part 2

51. The ground is always cold at night because the earth radiates heat to the atmosphere at night.

52. The escape velocity of an object from gravitational field of the planet increases with mass of the object and also increases with the mass of the planet. Escape velocity, v =√2Gmp/rp = √2gprp

53. A transverse wave and a longitudinal wave travelling in the same direction in a medium differ essentially in their direction of vibration of the particles of the medium.

54. The different time rates of flow of fluid is due to viscious force.

55. The electrical property of germanium can be altered drastically by the addition of impurities. The process is referred to as doping.

56. The wave property which can be used to confirm water to be a transverse wave is Polarization.

57. In a common emitter configuration, the output voltage is through the base.

58. When a ball rolls on smooth level ground, the motion of its center is Translational

59. A vapour whose molecules are in dynamic equilibrium with those of its own liquid is said to be Saturated.

60. In a good thermos flask, the main cause of heat loss is the silvered walls and shiny metals.

61. The north pole of a magnet can never be separated from the south pole because of a property known as magnetic dipole.

62. An iron spoon placed inside hot tea becomes hot due to the conductionof heat from the tea through the surface of the spoon.

63. A constant-volume gas thermometer operates under which gas law? Pressure law.

64. A vapour whose molecules are in dynamic equilibrium with those of its own liquid is said to be Saturated.

65. Red light travels faster than blue light when both of them pass through a glass prism because the refractive index of blue light is greater than that of red light.

66.  Heat reaches the food which is being cooked in a saucepan chiefly by Conduction and Convection.

67. The force that tend to pull an object undergoing circular motion towards the centre is Centripetal.

68. Radiation is energy travelling through space.

69. A body cannot undergo “relative motion”. Relative motion usually involves two bodies.

70. The type of wave emitted by a loudspeaker is Longitudinal.

71. The prolongation of sound wave after which the source has been withdrawn is called Reverberation.

72. The mouthpiece of a telephone primarily converts sound energy into Electrical.

73. The quality of a musical note depends on what? Harmonics

74. The resultant force in a couple is Zero

74. The most suitable instrument for measuring the diameter of a thin wire accurately is a micrometer screw gauge.

75. A rainbow viewed through a blue sheet of glass will appear blue.

76. The slope of a straight-line velocity-time graph represents uniform acceleration.

77. The unity cycle per second is the same as hertz.

78. Trombone is a wind instrument.

79. A chemical balance is used for measuring mass

80. Sound wave cannot be polarized.