Experiment: 01

Aim: To Verify Kirchhoff's Law

Viva Voce

Q.1 What is electric current?

Ans. Flow of electrons is called electric current.
Q.2 Define Electric Potential?
Ans. The capacity of charged body to work is called electric potential.
Q.3 What is Resistance?
Ans. The property of material by virtueof which it opposes or resist the flow of
current is known as resistance.
Q.4 Define Electric Energy?
Ans. The total amount of work done in an electric circuit is known as electric
energy.
Q.5 What is Electric Power?
Ans. The rate at which work is done in an electric circuit is known as electric
power.
Q.6 On what factors do the resistance offered by couductor depends on?
Ans. 1. It is directly proportional to its length.
2. It is inversely proportional to the area of cross-section of conductor.
3. Depends on temperatureof the conductor.
4. Depends on nature of material of conductor.
Q.7 What is conductance?
Ans. The property of conductor due to which it allows the current to pass
through it is known as conductance.
Q. 8 State Ohm's Law
Ans. It states that “for any conductor potential difference (V) between two
ends and current (I ) flowing between two ends of conductor are directly
proportional to each other”.
Q.9 State Kirchhoff's voltage Law.
Ans. “The algebric sum of product of current and corresponding resistance in
closed circuit is equal to the electromotive force in that circuit”.
Q.10 State Kirchoff's current Law.
Ans. “The algebric sum of the currents meeting at a node of electrical circuit is
zero or at any node sum of incoming current is always equal to sum of
outgoing currents”.
 Experiment : 02
Aim : To study Superposition Theorem
Viva Voce

Q.1 What is bilateral network?

Ans. A circuit or network in which the magnitude of current remains constant
when the polarity of source is reversed is called bilateral network.
Q.2 What are Passive Elements?
Ans. A passive element is an electrical component that does not generate power,
but instead dissipates, stores, and/or releases it. Passive elements include
resistances, capacitors, and coils (also called inductors).
Q. 3 What are Active Elements?
Ans. The active elements generate energy. Batteries, generators, operational
amplifiers, etc are active elements.
Q. 4 State Superposition theorem
Ans. “In a linear and bilateral network containing two or more than two source of
emf , the current flowing through any branch is algebric sum of currents that would
be produced due to each emf while acting alone and other sources of emf are to
be replaed by their internal resistances ”.
Q.5 Why voltage souce is short circuited in superposition theorem?
Ans. The internal resistance of ideal voltage source is zero. Hence while
deactivating voltage source in superposition theorem, it is short circuited
indicating zero internal resistance.
Q.6 Why Current souce is open circuited in superposition theorem?
Ans. The internal resistance of ideal current source is infinite. Hence while
deactivating current source in superposition theorem, it is open circuited
indicating infinite internal resistance.
 Experiment no : 03
Aim: To plot the B-H curve of transformer to study the behaviour of
Magnetic Material
Viva Voce

Q.1 What is Flux Density?

Ans. The number of flux passing per unit area is called flux density.
Q.2 Define Magnetomotive force
Ans. It is the force which drives the flux through the magnetic circuit. In case of
electromagnet , it is given by product of currentand number of turns in the coil.
Q.3 Define magnetic field intensity
Ans. It is defined as magnetomotive force per unit length of magnetic path.
Q. 4 Explain the term : Paramagnetic materials
Ans. The materials, which are not strongly attracted by the magnet, such as
aluminium, tin, platinum, magnesium, manganese etc. are known as
paramagnetic materials. The relative permeability is small but positive.
Q.5 Explain the term : Diamagnetic materials
Ans. The materials which are repelled by a magnet such as zinc,
mercury,lead,sulphur, copper,silver etc. are known as diamagnetic materials.
The permeability is slightly less than unity.
Q. 6 Explain the term : Ferromagnetic materials
Ans. The materials, which are strongly attracted by the magnet, such as iron,
steel, nickel, cobalt etc. are known as ferromagnetic materials. The
permeability is very high.
Q. 7 What is permeability ?
Ans. The ability of material to conduct flux is known as permeability. More the
permeability, more is the flux and hence stronger is the magnet.
Q. 8 Define Reluctance.
Ans. The opposition offered to the flow of flux by magnetic path is called
reluctance.
Q. 9 What is permeance?
Ans. The reciprocal of reluctance is known as permeance of magnetic circuit.
Q.10 What do you mean by leakage flux?
Ans. It is that flux which does not follow its intended or desired path in a magnetic
circuit.
Q.11 What do you mean by residual flux?
Ans. It is the flux which remains in a sample of magnetic material after the
magnetising force reduced to zero.
Q.12 What is coercivity?
Ans. It is the amount of magnetising force required to reduce the retained
magnetism to zero.
 Experiment no : 04
Aim : To determine R and L of choke coil
Viva Voce

Q. 1 What is mean by inductive reactance?

Ans. Opposition to the flow of alternating current offered by inductance is known as
inductive reactance.
Q.2 What is mean by capacitive reactance?
Ans. Opposition to the flow of alternating current offered by capacitance is known as
capacitive reactance.
Q.3 Define impedance
Ans. A combination of resistance, inductive reactance and capacitive reactance in an
AC circuit is termed as impedance.
 Experiment no: 05
Aim: To study R-L-C series circuit
Viva Voce

Q. 1 Define Time Period

Ans. Time required to complete one cycle is called time period.
Q. 2 Define Frequency
Ans. Number of cycles per second is called as frequency of alternating quantity.
Q. 3 Define root mean square (RMS) value.
Ans. It is the value od DC current which, when flowing through a given circuit for a
given period of time, produces the same heat as produced by alternating current
when flowing through the same time.
Q. 4 Define average value.
Ans. The average value of an alternating current is that DC current which transfers
across any circuit the same charge as it is transferrred by that alternating current
during the same time.
 Experiment no: 06
Aim : To study R-L-C Parallel Circuit
Viva Voce

Q.1 What is form factor?

Ans. The ratio of RMS value to Average value is the form factor.
Q. 2 Define Crest Factor
Ans. It is the ratio of maximum value to RMS value.
Q. 3 What is mean by inductive reactance?
Ans. Opposition to the flow of alternating current offered by inductance is known as
inductive reactance.
Q.4 What is mean by capacitive reactance?
Ans. Opposition to the flow of alternating current offered by capacitance is known as
capacitive reactance.
Q.5 Define impedance
Ans. A combination of resistance, inductive reactance and capacitive reactance
in an AC circuit is termed as impedance.
Q.6 Define Power Factor
Ans. Power factor is defined as the ratio of active power to apparent power.
Q. 7 What is Q- factor?
Ans. The efficiency of inductance and capacitance to store energy is measured in
terms of a factor called as Quality facor or Q- factor.
 Exrperiment no : 07
Aim : To perform Open circuit test and short circuit test on single
phase transformer
Viva Voce

Q. 1 What do you mean by electromagnetic induction?

Ans. According to faradays's law, whenever the flux linked with the conductor of
coil changes an emf is induced in that coil and the amount of this induced emf is
directly proportional to the rate of change of flux linked with the coil.
Q.2 Explain the concept of ideal transformer
Ans. An ideal transformer is one which has no losses i.e it's windingg have no
ohmic resistance, there is no magnetic leakage and hence which has no
heating and core lossses. In other words an ideal transformer consists of two
purely inductive coils wound on a loss free core.
Q. 3 How many losses are there in transformer?
Ans. There are two types of losses i.e iron losses and copper losses.Q.48 What is
the main purpose of using core in transformer?
Ans. To decrease the reluctance of magnetic circuit
Q.4 Why transformer cores are laminated?
Ans. In order to reduce eddy current losses
Q.5 What is the purpose of isolation transformer?
Ans. It is used to isolate primary winding from secondary winding.
 Experiment No: 08
Aim : To determine efficiency and voltage regulation of a single phase
transformer by direct loading method
Viva Voce

Q.1 Define Symmetrical or balanced supply system.

Ans. The three phase system in which three phase voltages are of identical
magnitudes and frequency and are displaced by 120 degree from each
other is called as symmetrical system.
Q.2 Define Efficiency of transformer.
Ans. Efficiency is defined as ratio of output power to input power.
Q.3 What will happen if DC supply is given to transformer ?
Ans. The heating losses in case of DC supply is very large so that is will burn the
primary winding causing permanent damage to the transformer.
Q.4 Why transformer is rated in VA or KVA?
Ans. The copper losses in transformer are dependent on current and iron losses are
dependent on voltage. Hence total losses depends on volt ampere(VA) and not
on the power factor. Therefore rating of transformer is in VA or KVA and not in W or
KW.
Q.5 Explain the concept of ideal transformer
Ans. An ideal transformer is one which has no losses i.e it's windingg have no
ohmic resistance, there is no magnetic leakage and hence which has no
heating and core lossses. In other words an ideal transformer consists of two
purely inductive coils wound on a loss free core.