NETWORK ANALYSIS LAB VIVA QUESTIONS AND ANSWERS
1. What you understand about the Q-factor of a coil?
We can define the Q factor of a coil as the ratio of inductive reactance to the resistance of a coil. Q factor refers to the ohmic losses of a coil with dimensionless unit and is inversely proportional to the coil quality.
Q factor = (inductive reactance )/(resistance of a coil).
2. Write down the examples of different types of current sources?
The devices which can be treated as current sources are the semiconductor devices like transistors and diodes.
3. How much efficiency can be attained during the maximum power transfer situation?
Will get maximum of 50% efficiency.
4. How can you define a filter?
Basically a filter is an electrical circuit, that is used for transmit signals with a specified frequency range.
5. What you know about an active filter?
Active filters involves components like operational amplifiers (OP-AMP). This op-amp circuit will introduce some gain in the signal. In other words, we can say that active filters is the type of filter which are designed using active components. The amplifiers included in filter design yields for the improvement of predictability, cost and performance of a filter.
6. How will you construct a band pass filter?
We can construct the band pass filter as a combination of two parallel tuned circuits and is a special type of LC circuit. The purpose of band pass filter is to allow a particular bandwidth frequency.
7. What you know about resistance of a material?
The resistance of a material is the property of a material for opposing the current flowing through the material. In other words, we can say that the property of opposing current through any material gives the resistance of that material. It is usually measured in ohms (Ω)
8. When current becomes zero (0), what happens to voltage?
When current reaches zero, voltage becomes constant.
9. For high voltage and frequency, which capacitor is usually used?
For high voltage and frequency applications, the ceramic capacitors are most commonly used.
We can easily control the thickness of the ceramic dielectric layer and can be produced as per the requirement of the desired voltage. The maximum rated voltage level of ceramic capacitors is 30 KV.
10. Explain Kirchoff 's voltage law and what are its limitations ?
As per Kirchoff 's voltage law, the algebraic sum of all branch voltages around any closed loop is zero in a network for all time instances.
The main limitation of Kirchoff 's voltage law is that in a distributed parameter network, the law is not applicable
11. Discuss Norton's Theorem?
Any linear bilateral network with output terminals can be changed by a single current source in parallel with Z (a single impedance).
12. What you understand about the maximum power transfer theorem?
In a dc network, when the load resistance and internal resistances becomes equal, the maximum power is transferred from source to the load. The maximum amount of power transferred is 50%.
13. What is the characteristic impedance of a network?
The characteristic impedance, also termed as the surge impedance can be calculated by the ratio of the amplitudes of voltage and current of a single wave propagates along the line. It is denoted by Z0.
14. Discuss Kirchoff 's current law?
Kirchoff 's current law states that at any node of a network, the algebraic sum of currents through the node is always equal to zero. In other words at a particular node, the sum of incoming currents and outgoing currents are same.
15. Give the advantages of constant K filters?
The main advantages of constant K filters are:
(a) In constant K filters, beyond the cut-off frequencies the attenuation doesn't rapidly increases.
(b) In the pass band, the characteristic impedance widely varies from the desired value.
16. For the formation of a resistor, what type of materials are used?
The materials used for the formation of a resistor are:
(a) Constantan (it is an alloy of nickel and copper. Nickel 45% and Copper 55%).
(b) Manganin (it is an alloy of copper, manganese and nickel. Nickel 2%, Manganese 12%, and Copper 86%).
17. In what situation, the three terminals of a resistor is used?
When the resistance is less than 1 ohm, the three terminals are used.
18. How we can calculate the equivalent impedance in Thevenin's theorem?
In Thevenin's theorem, the equivalent resistance can be calculated by, short circuiting all independent voltage sources and open circuiting all the independent current sources present in the circuit.
19. What is an unilateral circuit?
In an unilateral circuit, for both directions, the properties are not same. In other words we can say that unilateral circuits allows current to flow only in one direction.
20. List down the practical applications of filters?
The main applications of filters are they can be used in
(a) Voice frequency telegraphy
(b) TV broadcasting and telegraphy
(c) Multichannel communication
(d) Power supplies
(e) Audio electronics
(f) Radio communications
21. What you know about inductance?
The property of a electric conductor for opposing any change in the electric current passes through it can be termed as inductance. In a conductor, the flow of current creates a magnetic field around it.
Inductance of a coil:
Where,
L is the inductance in Henries (H),
VL is the voltage across the coil (V) and
di/dt is the rate of change of current in Amperes per second (A/s).
22. List the properties of a resistor?
The main properties of resistors are:
(a) Resistance to oxidation
(b) Corrosion and moisture
(c) High resistivity
(d) Mechanical strength
(e) Resistance value tolerance
(f) Protection against influences from the environment.
(g) Low temperature coefficient of resistance
(h) Low noise properties.
23. Differentiate active and passive networks?
The passive network has no current or voltage sources, while the active network has either current or voltage source.
24. What are the characteristics of a filter?
Under the pass band frequencies, an ideal filter will transmit signals without attenuation and completely suppresses the stop band frequencies. In other words, we can say that an ideal filter has a sharp cut-off profile.
25. What is the cut-off frequency. Draw the cut-off frequency for LPF?
The cut-off frequency can be defined as the frequency that separates the pass band and the attenuation band.
26. When current through an inductor remains constant, what happens to the voltage?
When current flowing through an inductor is constant, the voltage across the inductor becomes zero (0).
27. For making inductance coil, which material is used?
Marble is used for making the inductance coil because it will not get affected by atmospheric conditions.
28. Whether the theorems are applicable for ac sources?
No. They are applicable for dc circuits only.
29. Explain Ohm's law?
Ohm's law states that by keeping the physical condition as unchanged, the current through any conductor is directly proportional to the applied potential difference across it.
I = V/R
Where, I is the current, V is the voltage and R is the resistance.
30. What are the examples of voltage source and explain what are dependent sources?
The examples of voltage sources are battery and generator.
If strength of voltage or current changes in the source for any change in the connected network, then the network can be termed as dependent sources.
31. What is the units of current, charge and attenuation?
Current - Ampere (A)
Charge - Coulombs (C)
Attenuation - Decibel (dB) and Neper (Np)
32. How capacitance can be defined?
The capacitance can be defined as the ability to store electric charge within it. It is actually a measure of charge per unit voltage that can be stored in an element.
33. How can you define the Norton equivalent circuit?
The current generator placed in parallel to the internal resistance gives the Norton equivalent circuit.
34. List the advantages of active filters?
The main advantages of active filters over passive filters are:
(a) It is easy to tune
(b) It gives gain
(c) It eliminates bulky components
(d) It can be used for low impedance loads.
35. Define branch in a circuit?
Branch can be defined as a part of network that lies between two junction points.
36. Explain Thevenin's theorem?
Thevenin's theorem states that any linear network with output terminal can be changed by a single voltage source V in series with a single impedance.
37. State and explain Superposition Theorem?
In any linear bilateral resistive network having two or more voltage sources the current through any branch is the algebraic sum of the currents produced by each source acting alone at a time, when all other sources are replaced by their internal resistances.
