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Definitions in ICSE Physics SN 1. 2. 3. 4. 5. Term Force (F=ma, Vector) Contact Force Non-Contact Force Gravitational force 6. Force of gravity or weight Electro static force 7. Magnetic force 8. General character of non-contact force 9. Newton s first law of motion Newton s second law of motion 10. 11. Newton s third law of motion 12. 19. Inertia (SI unit- kg m/s) Linear Momentum (p=mv, vector) One dyne (dyne) One Newton (N) One Kilogram force (9.8 N) One gram force (980 dyne) Moment (vector quantity Newton meter)) Couple 20. Moment of couple 21. Equilibrium 22. Static Equilibrium 13. 14. 15. 16. 17. 18. Definition Force, Work, Energy, Power Force is a physical cause that changes or tends to change the shape or size or state of rest or state of motion of a body. Forces that are applied on body by making a physical contact. Forces experienced by bodies without being physically touched. Each particle in the universe attracts each other by a force due to its mass which is called as gravitational force. The force on a body due to earth s attraction towards it s centre is called the Force of gravity or weight of the body. The force between the charges is called Electro static force in which two like charges attracts and two unlike charges repel each other. The force between the magnetic poles is called Magnetic force in which two like poles attracts and two unlike poles repel each other. * Gravitational force is always attract whereas electro static force or magnetic force can be either attract or repel. * The magnitude of non-contact force is inversely proportional to square of distance of separation between two bodies. A body continues to be in state of rest or in state of motion unless an external force is applied to it. Rate of change of momentum is directly proportional to the force applied and the change in momentum takes place in the direction of applied force Every action has an equal and opposite reaction. Inherent property of a body to resist the change of state of rest or state of motion. It is directly proportional to mass. The momentum of body in linear motion the product of mass and velocity. One dyne is the force applied on a body of mass 1 gram to produce an acceleration of 1 cm/sec square. One Newton is the force applied on a body of mass 1 kilo-gram to produce an acceleration of 1 m/sec square. Force of gravity on a mass of 1 Kg. Force of gravity on a mass of 1 gm. Moment of force is equal to the product of magnitude of force and perpendicular distance of line of action of force from the axis of rotation. Two equal and opposite parallel forces not acting along the same line form a couple. Moment of couple is equal to the product of either force and the perpendicular distance between the line of action of both the forces(couple arm) When a number of forces acting on a body produce no change in state of rest or in state of motion, the body is said to be in equilibrium. When a number of forces acting on a body produce no change in 1 23. Dynamic Equilibrium 24. Centre of gravity (depends on the shape of the body) 25. Centrifugal force 26. Centripetal force 27. Work (Joule) Scalar One Joule (1 J = 1 N 1 m) One Erg (1 erg = 1 dyne 1 cm) Power(Watt) Watt 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. Energy Watt hour (1 Wh=3600 J) One Kilowatt hour (Kwh) Electron Volt (1eV= 1.6 10-19) Mechanical Energy Potential Energy Kinetic Energy Work energy theorem 44. Transitional Kinetic Energy Rotational Kinetic Energy Vibrational Kinetic Energy Gravitational potential Energy Energy degradation 45. Refraction of light 46. Laws of Refraction 41. 42. 43. state of rest, the body is said to be in Static equilibrium. When a number of forces acting on a body produce no change in in state of motion, the body is said to be in Dynamic equilibrium. Centre of gravity of a body is the point about which the algebraic sum of moment of weight of all the particles constituting the body is zero. Or the point about which weight of all particles of body acts. The force acting away from the centre of rotation when a body is in rotational motion. The force acting towards the centre of rotation when a body is in rotational motion. Work is said to be done only when the force applied on the body causing the body move. One Joule of work is said to be done when one Newton of force moves the body to a distance of one meter. One Erg of work is said to be done when one dyne of force moves the body to a distance of one centimeter. Rate of doing work per unit time.( 1 HP = 746 W) Watt is the power spent to perform 1 Joule of work is done in 1 sec. Energy is the capacity of a body to do work. 1Watt is the energy spent by an appliance in 1 hour. One Kilowatt is the energy spent by an appliance in 1 hour. One Electron Volt is the energy gained by an electron when it is accelerated through a potential difference of 1 volt. Energy possessed by a body due to states of its rest or motion. Energy possessed by a body due to states of its rest. Energy possessed by a body due to states of its motion. Work done by a force on a moving body is equal to the increase in kinetic energy. The kinetic energy of a body due to its motion in straight line motion. The kinetic energy of a body due to its rotational motion. The kinetic energy of a body due to its vibrational motion. The gravitational potential energy of a body due to force of attraction of earth. Gradual decrease of useful energy due to radiation loss or friction. Refraction The change in direction of the path of light, when it passes from one transparent medium to another transparent medium is called Refraction of light. The incident ray, the refracted ray and the normal at the point of incidence lie on the same plane. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for the given medium. The constant is called the refractive index of the second sin i medium with respect to the first medium. 1 2 = sinr 2 47. No refraction 48. Lateral displacement 49. 50. Absolute refractive index Refractive Index 51. Prism 52. 53. Angle of Prism Angle of deviation 54. Shift 55. Critical angle 56. Total Internal Reflection 57. Total reflecting prism 58. Lens 59. Second focus of a Angle of Incidence is 0. Refractive Index of two medium is equal. The perpendicular distance between the path of emergent ray and the direction of incident ray is called the lateral displacement. Directly proportional to the angle of incidence. Directly proportional to the thickness of the slab. Directly proportional to RI of the material. Inversely proportional to the wave length of light. Refractive index of a medium defined with respect to air. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for the given medium. The constant is called the refractive index of the second medium with respect to sin i the first medium. 1 2 = sinr A prism is a transparent refracting medium bounded by five plane surfaces inclined at some angles. The angle between two refracting surfaces is called angle of prism. The angle between the direction of incident ray and the emergent ray is called the angle of deviation. Angle of incidence increases the angle of deviation decreases. In the minimum deviation position, the angle of incidence = the angle of emergence. Beyond this, the angle of deviation increases. Refractive index increases angle of deviation increases Angle deviation in case of Violet colour(least wave length) is more than angle of deviation of Red colour(large wave length) Angle of prism increases, angle of deviation also increases. 1. Directly proportional to the thickness of the denser medium 2. Directly proportional to the refractive index of the material of the slab. 3. Inversely proportional to the wavelength of light. Critical angle is the angle of incidence in the denser medium corresponding to which the angle of refraction in the rarer medium is 900. Inversely proportional to the refractive index. Directly proportional to temperature. A ray of light in a denser medium is incident at the surface of the rarer medium such that the angle of incidence is greater than the critical angle for a given pair of media than the ray is totally reflected back ina denser medium. A total reflecting prism suffers total internalreflection inside the prism when the light is incident normally on any of its faces. 450900-450 prism is called the total reflecting prism. Lens is a transparent refracting medium bounded by two curved surfaces which are generally spherical or one curved and one plain surfaces. It is a point on the principal axis such that the rays of light, 3 convex lens 60. 61. 62. incident parallel to the principal axis pass after the refracting through the lens. Second focus of a It is a point on the principal axis such that the rays of light, concave lens incident parallel to the principal axis, appear to come from after the refracting through the lens. First focus of a convex It is a point on the principal axis such that the rays of light coming lens from it after the refraction from the lens become parallel to the principal axis. First focus of a It is a point on the principal axis such that the rays of light appears concave lens to meet at it after the refraction from the lens become parallel to the principal axis. 63. 64. 65. Centre of curvature Radii of curvature Optical centre 66. Focal length 67. Dispersion 68. 69. Spectrum Scattering 70. 71. Pure note Amplitude 72. 73. Time period Frequency 74. Wave length 75. 76. Wave velocity Longitudinal waves (Solid, liquid, gas) 77. 78. Transverse waves (Solid, surface of liquid) Echo 79. Free vibration 80. Damped vibration 81. Forced vibration 82. Resonance 83. Loudness Centre of the sphere of which the lens is part of. Radius of the sphere of which the lens is a part of. It is a point on the principal axis of the lens such that a ray of light passing through this point emerges parallel to its direction of incidence or passes undeviated or undispersed. Distance between the focus and the optical centre If lens is placed in water then the focal length increases. Thick lens has less focal length than thin lens. The phenomenon of splitting of white light by a prism into its constituent colours. The band of 7 colours seen on passing white light through prism. Process of absorption and re emission of light energy. Sound Pure note is a sound of single frequency. The maximum displacement of a particle of a medium through which sound is transmitted, about its mean position both sides. Time taken by a particle of a medium to complete one vibration. Number of vibrations made by a particle of a medium in one second. Distance travelled by a wave in one time period of vibration of particle of medium. Distance travelled by a wave in one second. Vibration of particle of a medium along the direction of propagation of wave thus forming compression and rarefaction in the medium. Vibration of particle of a medium along the direction of propagation of wave thus forming crest and troughs. The sound heard after reflection from a distant obstacle after the original sound is ceased. Periodic vibration of a body of constant amplitude in the absence of any external force on it. Periodic vibration of a body of decreasing amplitude in the presence of a resistive force . Vibration of a body which takes place under the influence of external periodic force acting on it. Resonance is a special case of forced vibration. When frequency of an externally applied periodic force on a body is equal to its natural frequency then the body begins to vibrate with increased amplitude. Loudness is the property by virtue of which a loud sound can be distinguished from a faint sound both having same pitch and 4 84. Pitch 85. Quality or timbre 86. Decibel 87. Intensity 88. Current (Ampere) Electric potential 89. 90. 91. 92. Potential (Volt) (Scalar Quantity) Potential Difference 93. Resistance (Ohm) Ohm s Law 94. Ohmic Resistor 95. Non-Ohmic Resistor 96. Super conductor 97. Resistivity 98. EMF 99. Terminal voltage 100. Voltage drop 101. 102. Internal Resistance Electric fuse quality. Pitch is characteristic of a sound by which a acute note can be distinguished from a grave and flat note. Quality or Timbre of a sound is a characteristic which distinguishes two sounds of same loudness and pitch but emitted by two different instruments. One dB is defined as the change in level of loudness when intensity of sound changes by 26%. Intensity of a wave at appoint of the medium is measured as the amount of sound energy passing per second normally through unit area at that point. Electricity, Electro Magnetism Amount of charge passing per second through a unit area of a conductor in one second. Electrical state of a conductor which determines the direction of flow of charge when two conductors are either kept in contact or joined by a metallic wire. Depends on size, shape, concentration of charges on the conductor. Amount of work done in moving a unit positive charge from infinity to that point. Amount of work done in moving a unit positive charge from one point to another. Obstruction offered to the flow of current by a conductor. Current flowing in a conductor is directly proportional to the potential difference applied across its ends provided that the physical conditions and temperature of the conductor remain constant. Conductor which obeys Ohm s law is called Ohmic resistor. Eg-Dilute Sulphuric acid,Nichrome and copper sulphate solution with copper electrodes. Conductor which does not obey Ohm s law is called Ohmic resistor. Eg-Diode valve,Triode valve, Junction diode and filament of a bulb. Substance of zero resistance at a very low temperature . Eg-Murcury below 4.2 K Resistivity of a material is the resistance offered by a wire of that material of unit length and unit area of cress section. Energy spent or work done per unit charge in taking a positive charge around the complete circuit of the cell. Depend on material of electrode, electrolyte used Not depend on-distance between electrodes, amount of electrolyte and shape of electrode. Energy spent or work done per unit charge in taking a positive charge around the circuit connected across the terminal of the cell. Energy spent or work done per unit charge in taking a positive charge through the electrolyte of the cell. Obstruction by the electrolyte to the flow of current. Safety device which is used to prevent flow of excessive current in the circuit. 5 103. Switch 104. Heat 105. Specific heat capacity 106. Heat Capacity or Thermal Capacity 107. Specific latent heat 108. Latent heat 109. Thermionic emission 110. 111. Work function or Threshold energy Electronvolt(eV) 112. Atomic number(Z) 113. Mass number(A) 114. Isotops 115. Isobars 116. Isotones 117. Radioactivity 118. Half-life 119. Carbon-14 dating or carbon-dating 120. Background radiation On-Off device for a current in a circuit Heat It is a form of energy (kinetic and potential) possessed by all the molecules of the substance. It is defined as the amount of heat energy required to raise the temperature of unit mass of the substance through 1 K or 1 0C Heat Capacity or Thermal Capacity of a body is defined as the amount of heat energy required to raise the temperature of the body through 1 K or 1 0C. It is the amount of heat required to change the physical state of a body of unit mass without any change ofbtemperature at normal atmospheric pressure. It is the amount of heat required to convert unit mass of a substance from its solid state to the liquid state, without any change of temperature at normal atmospheric pressure. Radioactivity It is the emission of free electrons from the surface of a metal on heating. It is the minimum amount of heat energy required to emit a free electron from the surface of a metal. It is the amount of work done when an electron moves through a potential difference of one volt. 1 eV = 1.6X10-19J. It is the number of protons present in the neucleous of an atom of the element. It is the total number of protons and neutrons present in the neucleous of an atom of an element. Atoms of the same element having same atomic number but different mass numbers are called isotop. Atoms of the same element having different atomic number but same mass numbers are called isobar. Atoms of the same element having same atomic number but different number of neutrons are called isotones. The process of spontaneous emission of -particles and -particles and -radiation from the nucleus of an unstable atom and thereby changing the nucleus into a nucleus of a new element is called radioactivity. It is the time by which number of atoms in a radioactive substance becomes half of its original value by radioactive disintegration process. It is the process of determining the age of very old civilizations, fossils, plants and other archeological specimens by using the property of radioactive decay of radioisotope of carbon 6C14. It is the radioactive radiations present in the earth s atmosphere due to presence of radioactive substances in the earth s crusts and cosmic rays coming from heavenly bodies. 6
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