Network Analysis Interview Questions and Answers:
1. What is an electric network?
Ans. An electric network is an interconnection of physical electrical devices such as an energy source (or sources), an energy convertor or convertors (load or loads), and conductors that connect them.
2. What is an energy source?
Ans. An energy source (or source), such as primary or secondary cell, a generator, and the like, is a device that converts chemical, mechanical, thermal or some other form of energy into the electrical energy.
3. What is an energy convertor?
Ans. An energy convertor, also called the load, such as lamp, heating appliance, or electric motor, converts electrical energy into light, heat, mechanical work etc.
4, What is an active element?
Ans. The elements which supply energy to the network are known as active elements. The voltage sources like batteries, dc generators, ac generators and current sources like photoelectric cells, metadyne generators fall under the category of active elements. Most of the semiconductor devices like transistors are treated as current sources.
5. What is meant by ‘node’?
Ans. A junction or node is a point in a network where two or more branches meet.
6. Distinguish between mesh and loop of an electric circuit.
7. Ans. A loop is a closed path in a electric circuit formed by a number of connected branches. Mesh is a loop that contains no other loop within it.
8. What is Ohm’s law?
Ans. Physical state i.e. temperature rise etc. remaining the same the current flowing through a conductor is directly proportional to the potential difference applied ac ross its ends.
9. What are the limitations of Ohm’s law?
Ans. Ohm’s law cannot be applied to the circuits consisting of (i) electronic tubes or transistors (because such elements are not bilateral) and (ii) nonlinear elements such as powdered iron, electric arc etc.
10. What is current distribution law for parallel circuits ?
Ans. Current in any branch of a parallel circuit is directly proportional to its respective conductance and is equal to the total current flowing through the circuit multiplied by the ratio of the conductance of the branch to that of the circuit.
11. Define Kirchhoff’s current law (KCL).
Ans. According to KCL law in any network of wires carrying currents, the algebraic sum of all currents meeting at a point (or junction) is zero or the sum of incoming currents towards any point is equal to the sum of outgoing currents away from that point.
12. State Kirchhoff s voltage law.
Ans. According to KVL law in any closed circuit or mesh the algebraic sum of emfs acting in that circuit or mesh is equal to the algebraic sum of the products of the currents and resistances of each part of the circuit.
13. What is the utility of superposition theorem?
Ans. This theorem is applied when we are to determine the current in one particular branch of a network containing several voltage sources or current sources or both voltage sources and current sources.
14. What is Thevenin theorem?
Ans. Thevenin’s theorem may be stated as follows:
The current in any passive circuit element (which may be called RL) in a network is the same as would be obtained if RL were supplied with a source voltage VOC or VT in series with an equivalent resistance Rin or RT; VOC being the open-circuit voltage at the terminals from which RL has been removed and RT being the resistance that would be measured at these terminals after all sources have been removed and each source has been replaced by its internal resistance.
15. What is the utility of Thevenin theorem?
Ans. Thevenin’s theorem is advantageous when we are to determine the current in a particular element of a linear bilateral network particularly when it is desired to find the current which flows through a resistor for its different values. It makes the solution of the complicated networks (particularly electronic networks) quite simple.
16. In what respect is Norton’s theorem similar to Thevenin’s theorem ? In what respect do they differ?
Ans. Norton’s theorem is in fact, an alternative to the Thevenin’s theorem. Whereas by Thevenin’s theorem a complex two-terminal network may be simplified for solution by reducing it into a simple circuit in which the so called open-circuit voltage and looking-back resistance are connected in series with the load resistance, by Norton’s theorem network is reduced into a simple circuit in which a parallel combination of constant current source and looking-hack resistance feeds the load resistance.
In both theorems use of resistance looking back into the network from the load terminals, with all sources removed leaving their internal resistances in the circuit is made. However, while solving circuit by Thevenin’s theorem, the open-circuit voltage is determined at the load terminals with the load removed whereas in Norton’s method use of a fictitious constant current source is made, the constant current delivered being equal to the current that would pass into a short circuit connected across the output terminals of the given network.