ELECTRICAL MEASURING INSTRUMENTS For the detection or measurement of electric current, potential difference, and resistance certain instruments have been devised viz. The galvanometer for the detection of small currents measurements of small currents of the order of micro amperes or mili amperes the voltmeter or potentiometer for the measurement of potential difference (and voltage) between two points of a circuit are the EMF of a source the ammeter for the measurement of large currents the wheatstone bridge the meter Bridge the post office box and the ohmmeter for the measurement of resistance. THE MOVING COIL GALVANOMETER The moving coil galvanometer is a basic electrical instrument it is used for the detection (and Measurement) of small currents. Its underlying principle is the fact that when a current flows in a rectangular coil placed in a magnetic field it experiences a magnetic torque. If it is free to rotate under a controlling torque, it rotates through an angle proportional t...
NUCLEAR RADIATIONS INTERACTION OF NUCLEAR RADIATIONS WITH MATTER In the previous article we have discussed natural radioactivity in which α and β particles and γ-rays are emitted from the disintegrating nucleus of an atom.In nuclear fission and fusion reactions neutrons and other particles together with certain radiations are emitted from the nucleus.Moreover, interaction of high energy particles (neutral or artificial) with matter produce certain nuclear or atomic reactions with emission of particles like protons,deutrons,neutrons and ionizing radiations like γ-rays from the nucleus and x-rays and ultraviolet rays from the atom.These particles and radiations have been studied carefully for their properties and effects with are as follows: ALPHA (α) PARTICLES It shoots out from the nucleus with a high velocity ( 0.1 × 10 ^ 8 m/s ). Thus it possesses very high energy 7.7 MeV for the most energetic from R ac.Due to its large size more charge and high energy it can make very l...