electricalengineeringquestionanswer

Q: Why 3 phase power is used and not 6 phase or 12 phase? There are two reasons: (1) using three phases results in the lowest conductor cost/watt to transmit power; (2) using three phases displaced in space around a cylinder by 120 degrees results in a rotating magnetic field when the three phases are excited by three voltage sources displaced in time by 120 electrical degrees - this is a fundamental energy conversion principle for the operation of AC motors and generators. Q:What is transmission line? Transmission line is the long conductor with special design (bundled) to carry bulk amount of generated power at very high voltage from one station to another as per variation of the voltage level. Q:What are the types of transmission line? Short Transmission Line Medium Transmission Line long Transmission Line Q: What is short transmission line? Length is about 50 km. Voltage level is up to 20 kV Capacitance effect is negligible Only resistance and inductance are taken in calculation. Q...

Electrical Circuit Theorems: To solve problems in electrical networks, there are number circuit theorems have been developed like (1) Kirchhoff's laws (2) Superposition theorem (3) Thevenin theorem (4) Norton Theorem (5) The maximum power transfer theorem In this post we have listed all these theorems. We believe that this post will serve as a ready reference for you. Kirchhoff's laws: (a) Current Law:  At any junction in an electric circuit the total current flowing towards that junction is equal to the total current flowing away from the junction, i.e. I =0 (b) Voltage Law:  In any closed loop in a network, the algebraic sum of the voltage drops (i.e.products of current and resistance) taken around the loop is equal to the resultant e.m.f. acting in that loop. Superposition Theorem: In any network made up of linear resistances and containing more than one source of EMF, the resultant current flowing in any branch is the algebraic sum of the currents that would flow in that ...

Q.Define combinational logic  When  logic  gates  are  connected  together  to  produce a  specified  output  for  certain  specified combinations of  input  variables,  with no  storage  involved, the  resulting  circuit is  called combinational logic.  Q. Define Half adder and full adder  The logic circuit that performs the addition of two bits is a half adder. The circuit that  performs the addition of three bits is a full adder.  Q. Define Decoder  A decoder is a multiple - input multiple output logic circuit that converts coded  inputs into coded outputs where the input and output codes are different.  Q. What is binary decoder?   A  decoder  is  a  combinational  circuit  that  converts binary  information  from  n  input  lines to a maximum of  2 n   out puts line...

Q.What is Microprocessor? Give the power supply & clock frequency of 8085  A microprocessor is a multipurpose, programmable logic device that reads  binary  instructions  from  a  storage  device  called  memory  accepts  binary  data  as  input  and  processes  data  according  to  those  instructions  and  provides  result  as  output. The power supply of 8085 is +5V and clock frequency in 3MHz.  Q. List few applications of microprocessor-based system.  It is used:  i. For  measurements,  display  and  control  of  current,  voltage,  temperature, pressure, etc.  ii.  For traffic control and industrial tool control.  iii.  For speed control of machines.  Q. What are the functions of an accumulator?  The  accumulator  is  the  register  associate...

Q.What are semiconductors? The materials whose electrical property lies between those of conductors and insulators  are known as Semiconductors. Ex germanium, silicon. It has two types. 1. Intrinsic semiconductor 2. Extrinsic semiconductor. Q.What is the order of energy gap in a conductor, semi conductor, and  insulator?.  Conductor - no energy gap  Semi Conductor - It is of the order of 1 ev.  Insulator - 6 ev (or) more than 6 ev.  Q. Zener effect and avalanche effect are the two possible break down mechanisms  that helps the external current . Why ? Zener effect : The electric field in the depletion layer reach a point that it can break the covalent bonds and generate electron–hole pairs.  Avalanche breakdown : The minority carriers that cross the depletion layer  under the influence of the electric field gain sufficient kinetic energy to be able to  break covalent bond in atoms which they collide.  Q.Why does the conductivity of ...