gurudev shree ramlal ji siyag

Electrical important points for RAILWAY and SSC JEN  [summary of all posts] ::::::::: # best conductor silver > copper > gold > aluminium # best insulator is Diamond # carbon is semi conductor # copper is not present in suffisient quantity on earth so aluminium is used as a conductor # galium arsenide for Red light from LED # galium phasphide for Green light from LED # in seven segment display 7 LED's are used # photo coupler = LED + Photo Diode # Diode = uncontrolled rectifier # SCR= controlled rectifier # in Scr, gate is control element # Scr is 4 layer, 3 junction, 3 terminal device # diode is 2 layer, 1 junction, 2 terminal device # p-type semi conductor = trivalent impurity.. # n-type semi conductor = panta valent impurity # transistor use as a amplifier... # in transistor collector has largest size and base has smallest size # in transistor emiter has maximum dopping and base has minimum dopping # Common emitter connection is suitable for amplif...