Physics stpm sem 3 definition

Simple harmonic motion: a system is said to execute simple harmonic motion if the acceleration of a body is directly proportional to the displacement from a fixed point and it is always directed towards the fixed point. Damping: it is a process in which the amplitude of an oscillating system decays progressively with time due to the work done against dissipative forces. Forced oscillation: it is an oscillation of a system caused by the periodic application of force to the system by an external agent and the system is forced to oscillate at the forcing frequency of the external agent. Resonance is a phenomenon in which a system oscillates with maximum amplitude when the forcing frequency is equal to the natural frequency of the system. Progressive waves transfer energy from 1 point to another without transferring the matter of the wave medium. Wave intensity at a point is defined as the rate of transfer of wave energy to a unit area which is perpendicular to the direction of propagation of the wave. Principle of superposition states that when two or more waves of the same type meet at a point. The resultant displacement at the point is given by the vector sum of displacement of the individual waves. Standing waves are produced when two identical waves travelling in opposite direction superimpose. The two waves that meet must be coherent, meaning they have same speed and frequency and maintain a constant phase relationship. Intensity level of sound: the intensity of sound at a point is defined as the rate of change of energy received by a unit area placed perpendicularly to the direction of propagation of sound. Beats are periodic vibration of sound intensity detected caused by the superimposes of two notes of slightly different frequencies but having the same amplitude. The work function of a metal is the minimum energy required to tease an electron from the surface of the metal. The threshold frequency of the metal is the minimum frequency of an em radiation needed to release an electron from the metal surface or it is the maximum wavelength of em radiation below which no photoelectron will be emitted from the metal surface irradiated by the radiation. De Broglie hypothesis states that under certain circumstances a particle exhibits wave properties and under other conditions a wave exhibits properties of a particle. Energy level in Bohr’s model is defined as a fixed energy corresponding to the orbits in which its electrons move around the nucleus.

Ionization energy is defined as the energy required by an electron in the ground state to escape to infinity completely free from the attraction of the nucleus. Ground state is defined as the lowest stable energy state of an atom. Bragg’s law states that x-rays are being diffracted by the crystal lattice if their wavelength is approximately equal to the distance between two consecutive atomic planes of crystal. The mass defect of a nucleus is the difference between the observed mass of the nucleus and the total mass of the individual nucleon that constitute the nucleus. The binding energy per nucleon is defined as the average energy per nucleon to split a nucleus completely into separate nucleon. Radioactive decay is the spontaneous and random process in which an unstable nucleus will disintegrate by emitting radiations such as alpha, beta and gamma so that a more stable nucleus is formed. The decay constant of a radioactive sample is defined as the fraction of atoms of nuclei which is going to decay over a certain short time interval. The half life of a radioactive sample is defined as the time taken for half the unstable nuclei present in a sample to decay.