Kirchhoff Law for Electrical Engineering

Kirchhoff Law for Electrical Engineering

For complex circuit computations, the following two laws first stated by Gutsav R. Kirchhoff (1824-1887) are indispensable.

Kirchhoff Law for Electrical Engineering


Kirchhoff's First Law (Point or Current Law)
The sum of the currents entering a junction is equal to the sum of the currents leaving the junction.

i.e., Sum of Currents entering = Sum of currents leaving.

Kirchhoff's Second Law (Mesh or Voltage Law)
The sum of e.m.f. (rise of potential) around any closed loop of a circuit equals the sum of the potential drops in that loop.

Considering a rise of potential as positive (+ ve) and a drop of potential as negative (-ve), the algebraic sum of potential differences (voltages) around a closed loop of a circuit is zero.

Sum of E - Sum of IR drops = 0 (around closed loop) i.e. Sum of E = Sum of  IR or Sum of Potential rises = Sum of potential drops

Applications of Kirchhoff s Laws

Kirchhoff's laws may be employed in the following methods of solving networks:
1. Branch-current method.
2. Maxwell's loop (or mesh) current method.
3. Nodal voltage method.

Also, SeeHow to Read Resistor Color Code

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How to Read Resistor Color Code

How to Read Resistor Color Code

  • Resistance is measured in units called ohms.
  • Wire wound resistors normally have their values in ohms and tolerance in percent stamped on them.
  • For carbon or composition resistors a color code is used.
The resistance values, for several years, have been coded by three colored bands painted around the body of the resistors. If the tolerance is either 5 or 10 percent, a fourth color bond is added. The position of the bands is shown below.


How to Read Resistor Color Code




  • The first two colors tell the first two digits in the resistance value.
  • The third band tells how many zeros follow the first two digits.
  • Sometimes a fourth band is present. This band tells the tolerance and will be either gold or silver. A gold band means 5% tolerance, silver 10%, and no fourth band, 20%. The tolerance band tells how close the resistance should be to the value shown by the other three bands.



The Producer of Reading the band is given below.



How to Read Resistor Color Code

The Blue-Red-Orange bands signify 62 followed by three zero and would be read as 62000 ohms +-20%.

Also SeeImportant Current Electricity Notes for Students

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Important Current Electricity Notes for Students

Important Current Electricity Notes

Today we are going to Provide you Current Electricity Notes like Electromotive Force, Resistance, Ohm's Law, Electrical Energy etc.

What is Electromotive Force?
Electromotive Force (E.M.F.) is the force that causes a current of electricity to flow. The Volte is the unit of potential difference and electromotive force.


Current Electricity Notes

What is Resistance in Electrical Engineering?
The Opposition to the flow of electron is called electrical Resistance. Resistance may also be defined as "The property of the electric circuit which opposes the flow of current". The Practical Unit of Electrical Resistance is ohm.

What is Ohm's Law?
"For a fixed metal conductor, the temperature and other conditions remaining constant, the current I through it is proportional to the potential difference V between its ends".

in other words, V/I = Constant or V/I = R, where R is the resistance of the conductor between the two points.

Also See - Top Electrical Engineering MCQ on Simple DC Networks

What is Electrical Energy?
Electrical Energy is expressed in terms of KW (kilowatt = 1000W) or MW (megawatt = 1000 KW)

1 kWh = 1 kw * 1 hour = 1000 watt-hours (=1000*60*60 watt-sec.)

What is Linear and Non-linear Resistor?
Linear Resistor - A Linear resistor is one which obeys Ohm's law. A circuit which contains only linear components is called a linear circuit.

Non-linear Resistor - Such elements in which the V/I (volt-ampere) plots are not straight lines but curves are called non-linear resistors or non-linear elements.


What is the Limitation of Ohm's Law?
Ohm's law does not apply under the following conditions:
1. Electrolytes where enormous gases are produced on either electrode.
2. Non-linear resistors like vacuum radio valves, semi-conductors, gas-filled tubes etc.
3. Arc lamps.
4. Metals which get heated up due to the flow of current through.
5. Appliances like metal rectifiers, crystal detectors, etc. in which operation depends on the direction of the current.

Classification of Resistors
The resistors 'are classified as follows:

1. Fixed resistors - The fixed resistor is the simplest type of resistor. Fixed means that the unit is so constructed that its resistance value is constant and unchangeable. These are made of a carbon composition and have a cover of black or brown hard plastics.

2. Tapped resistors - A tapped resistor is a resistor which has a tap, or connection, somewhere along the resistance material. These resistors are usually wire wound type. If they have more than one tap, they will have a separate terminal for each.

Also See - Top 24 Basic Electrical Engineering Questions with Answers

3. Variable resistors - A variable resistor has a movable contact that is used to adjust or select the resistance value between two or more terminals. A variable resistor is commonly called a control.


4. Special resistors - The most common type of special resistors is the fusible type. A fusible resistor has a definite resistance value and it protects the circuit much like a fuse. Another special resistor is the temperature compensating unit. Such resistors are used to provide special control of the circuit that must be extremely stable in their operation.

We hope that this post "Important Current Electricity Notes for Students" will help you in your preparation. if you have any suggestion and request, you can tell us through comment here.


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What is Power/Electrical Engineering All Detail

What is Power Engineering

This Post is about What is Power or Electrical Engineering? If you wish to pursue careers in the field of engineering, then electrical or power engineering is Evergreen in case of possibilities and demand. There is a need for electrical engineers in every area from home to industrial and even in space applications.

What is Power Engineering
Due to the increasing use of modern machines and gadgets in our life, there is a need to make the devices more capable, manageable and reliable. Due to this increasing demand, the employment of electrical engineers is increasing.

What is the necessary qualification for Power or Electrical Engineering?

Intermediate is necessary from the science stream to study electrical engineering. After this, you can achieve a Bachelor Degree or Master degree beyond that in this course.

In what new areas are employment opportunities for Power/Electrical Engineers?

In recent times, the electrical engineering sector is spread fast in advanced technology areas like Semiconductor, Networking, Communications Navigation System, Computers and Data Analysis.


Research in Electrical/Power Engineering

Institutes and companies are also investing in research in new areas for the graduate of electrical engineering. In these areas, a lot of research project such as Distributed Grid Control, Smart Grid, source of non-conventional energy, oil and gas extraction from the ocean, can be found for electrical engineers.

Job in the Data Digitization Sector

Government and individuals are focusing on increasing special data digitization and networking. In this way, electrical graduates are most likely to get jobs in the field of network and communication. With the advancement in the field of communication, there are definitely a lot of digital data, which need to be analyzed. These vigorous systems of data collection have opened up many opportunities for electrical engineers.

We Hope You Enjoy Reading This Article about What is Power or Electrical Engineering If You want more Article like this Comment Below.

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Electrical Engineering Basics Questions with Answers Part 1

Electrical Engineering Basics Questions

Today we are Going to Provide You Electrical engineering interview questions from Electrical Engineering Basics Chapter.

All matter is composed of - Atoms

To be a conductor, the substance must contain some mobile electrons

Conductivity depends on the number of electrons. - (Yes/No)

The energy level of an electron decreases as its distance from the nucleus increases.  - (Yes/No)

Electrical Engineering Basics Questions


Atoms with fewer than four valence electrons are good conductors.



Atoms with more than four valence electrons are poor conductors.

Atoms with four valence electrons are - semi-conductors

Mass of an electron is approximately equal to 1/1000 mass of the proton - (Yes/No)

The diameter of an electron = 10-15 Meter (Yes/No)

When an electron is removed from a neutral atom, this atom becomes positively charged and is called a - Positive Ion

The controlled movement of electrons through a substance is called - Current

Electromotive force is the force that causes a current of electricity to flow.

Also Read - Basic of Electrical Engineering and Basic Electrical Formulas

The is a unit of potential difference and electromotive force - Volt

Electron-volt is a unit in terms of which the energies of atomic particles are expressed. (Yes/No)

The opposition to the flow of electrons is called electrical resistance

The practical unit of electric resistance is mho. (Yes/No)

Resistivity of a material may be defined as the resistance between the opposite faces of a meter cube of that material.


The reciprocal of specific resistance of a material is called its conductivity

The unit of conductivity is ohm/ meter. (Yes/No)

The resistance of metal conductors increases with rising of temperature. (Yes/No)

The resistance of semiconductors and all electrolytes decreases as the temperature rises.

A linear resistor is one which Obey's Ohm's law.

At very low temperature, some metals acquire zero electrical resistance and zero magnetic induction, the property known as super-conductivity

A fixed resistor is the simplest type of resistor and its value is constant and unchangeable.

Also ReadImportant Topic on A.C. Fundamentals

A variable resistor is commonly called a control. (Yes/No)

The most common type of special resistor is the fusible type. (Yes/No)

In a series combination of resistors, the current flowing through each resistor is different. (Yes/No

The resistivity of pure semiconductors is of the order of 1 ohm-meters. (Yes/No)

The symbol marked R8 represents a fixed resistor.

The part represented by the symbol marked R1 is a Variable resistor.

This is Part 1 of Electrical Engineering Basics Questions with Answers, these Questions and Answers are Very Important For Your Exam and Interview. Keep Visiting ElectricalNotes4u for Latest Electrical Engineering MCQ, Notes, Interview Questions with Answers.

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Top Electrical Engineering MCQ on Simple DC Networks

Top Electrical Engineering MCQ on Simple DC Networks

1 - In a series circuit, which of the parameters remain constant across all circuit elements such as resistor, capacitor and inductor etcetera?
a) Voltage
b) Current
c) Both voltage and current
d) Neither voltage nor current.

Answer: b
MCQ on Simple DC Networks

2 - If there are two bulbs connected in series and one blows out, what happens to the other bulb?
a) The other bulb continues to glow with the same brightness
b) The other bulb stops glowing
c) The other bulb glows with increased brightness
d) The other bulb also burns out

Answer: b

3 - Voltage across a series resistor circuit is proportional to?
a) The amount of time the circuit was on for
b) The value of the resistance itself
c) The value of the other resistances in the circuit
d) The power in the circuit

Answer: b

4 - Many resistors connected in series will?
a) Divide the voltage proportionally among all the resistors
b) Divide the current proportionally
c) Increase the source voltage in proportion to the values of the resistors
d) Reduce the power to zero

Answer: a

5 - What happens to the current in the series circuit if the resistance is doubled?
a) It becomes half its original value
b) It becomes double its original value
c) It becomes zero
d) It becomes infinity

Answer: a

Also Read - MCQ on Control System for Electrical Engineering

6 - If two bulbs are connected in parallel and one bulb blows out, what happens to the other bulb?
a) The other bulb blows out as well
b) The other bulb continues to glow with the same brightness
c) The other bulb glows with increased brightness
d) The other bulb stops glowing

Answer: b

7 - The current in each branch of a parallel circuit is proportional to_______
a) The amount of time the circuit is on for
b) Proportional to the value of the resistors
c) Equal in all branches
d) Proportional to the power in the circuit

Answer: b

8 - The currents in the three branches of a parallel circuit are 3A, 4A and 5A. What is the current leaving it?
a) 0A
b) Insufficient data provided
c) The largest one among the three values
d) 12A

Answer: d

9 - Batteries are generally connected in______
a) Series
b) Parallel
c) Either series or parallel
d) Neither series nor parallel

Answer: a

10 - What is the value of current if a 50C charge flows in a conductor over a period of 5 seconds?
a) 5A
b) 10A
c) 15A
d) 20A

Answer: b

11 - KCL can be applied for __________
a) Planar networks
b) Non-planar networks
c) Both planar and non-planar
d) Neither planar nor non-planar

Answer: c

12 - KVL is applied in ____________
a) Mesh analysis
b) Nodal analysis
c) Both mesh and nodal
d) Neither mesh nor nodal

Answer: a

13 - A 250V bulb passes a current of 0.3A. Calculate the power in the lamp.
a) 75W
b) 50W
c) 25W
d) 90W

Answer: a

14 - Kilowatt-hour(kWh) is a unit of?
a) Current
b) Power
c) Energy
d) Resistance

Answer: c

15 - Calculate the work done in a resistor of 20 ohm carrying 5A of current in 3 hours.
a) 1.5J
b) 15J
c) 1.5kWh
d) 15kWh

Answer: c

16 - The SI unit of power is?
a) kW(kilo-watt)
b) J/s(joules per second)
c) Ws(watt-second)
d) J/h(joules per hour

Answer: b

17 - Out of the following, which one is not a source of electrical energy?
a) Solar cell
b) Battery
c) Potentiometer
d) Generator

Answer: c

18 - A battery converts___________
a) Electrical energy to chemical energy
b) Chemical energy to electrical energy
c) Mechanical energy to electrical energy
d) Chemical energy to mechanical energy

Answer: b

19 - A wire of length 2m and another wire of length 5m are made up of the same material and have the same area of cross section, which wire has higher resistance?
a) Both have equal resistance
b) The 2m wire has higher resistance
c) The 5m wire has higher resistance
d) The value of resistance cannot be determined from the given data

Answer: c

20 - Which, among the following is a unit for resistivity?
a) ohm/metre
b) ohm/metre2
c) ohm-metre
d) ohm-metre2

Answer: c

21 - The reciprocal of resistivity is________
a) Conductance
b) Resistance
c) Conductivity
d) Impedance

Answer: c

22 - The resistance of pure metals ___________
a) Increases with increase in temperature
b) Decreases with increase in temperature
c) Remains the same with increase in temperature
d) Becomes zero with increase in temperature

Answer: a

23 - The temperature of a coil cannot be measured by which of the following methods?
a) Thermometer
b) Increase in resistance of the coil
c) Thermo-junctions embedded in the coil
d) Caloriemeter

Answer: d

24 - Materials having resistance almost equal to zero is_______
a) Semi-conductor
b) Conductor
c) Superconductors
d) Insulators

Answer: c
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Top 24 Basic Electrical Engineering Questions with Answers

Basic Electrical Engineering Questions with Answers


1- In a constant voltage DC circuit, when the resistance increases, the current will 
a) Decrease 
a) Stop 
a) Increase 
a) Remains constant 

Answer: a

2 - The unit of electrical resistance is 
a) Volt 
a) Amp 
a) Ohm 
a) Coulomb 

Answer: c
Basic Electrical Engineering Questions

3 - The current out of an ideal current source is 
a) Zero 
a) Constant 
a) Load resistance dependent 
a) Internal resistance dependent 

Answer: b



4 - In a series circuit, which of the parameters remain constant across all circuit elements such as resistor, capacitor and inductor etcetera? 
a) Voltage 
b) Current 
c) Both voltage and current 
d) Neither voltage nor current 

Answer: b

5 - If there are two bulbs connected in series and one blows out, what happens to the other bulb? 
a) The other bulb continues to glow with the same brightness 
b) The other bulb stops glowing 
c) The other bulb glows with increased brightness 
d) The other bulb also burns out
Answer: b

6 - What happens to the current in the series circuit if the resistance is doubled? 
a) It becomes half its original value 
b) It becomes double its original value 
c) It becomes zero 
d) It becomes infinity 

Answer: a

7 - The current in each branch of a parallel circuit is proportional to_______ 
a) The amount of time the circuit is on for 
b) Proportional to the value of the resistors 
c) Equal in all branches 
d) Proportional to the power in the circuit 

Answer: b

8 - The currents in the three branches of a parallel circuit are 3A, 4A and 5A. What is the current leaving it? 
a) 0A 
b) Insufficient data provided 
c) The largest one among the three values 
d) 12A 

Answer: d

9 - Batteries are generally connected in______ 
a) Series b) Parallel 
c) Either series or parallel 
d) Neither series nor parallel 

Answer: a

10 - What is the value of current if a 50C charge flows in a conductor over a period of 5 seconds? 
a) 5A 
b) 10A 
c) 15A 
d) 20A 

Answer: b

11 - KCL can be applied for __________ 
a) Planar networks 
b) Non-planar networks 
c) Both planar and non-planar 
d) Neither planar nor non-planar 

Answer: c

12 - What is the basic law that has to be followed in order to analyze ant circuit? 
a) Newton’s laws 
b) Faraday’s laws 
c) Ampere’s laws 
d) Kirchhoff’s law 

Answer: d



13 - KVL is applied in ____________ 
a) Mesh analysis 
b) Nodal analysis 
c) Both mesh and nodal 
d) Neither mesh nor nodal 

Answer: a

14 - A 250V bulb passes a current of 0.3A. Calculate the power in the lamp.
a) 75W
b) 50W
c) 25W
d) 90W

Answer: a

15 - Calculate the work done in a resistor of 20 ohm carrying 5A of current in 3 hours.
a) 1.5J
b) 15J
c) 1.5kWh
d) 15kWh

Answer: c

16 - The SI unit of power is?
a) kW(kilo-watt)
b) J/s(joules per second)
c) Ws(watt-second)
d) J/h(joules per hour

Answer: b

17 - Which among the following is a unit for electrical energy?
a) V(volt)
b) Wh(kilowatt-hour)
c) Ohm
d) C(coloumb)

Answer: b

18 - A battery converts___________
a) Electrical energy to chemical energy
b) Chemical energy to electrical energy
c) Mechanical energy to electrical energy
d) Chemical energy to mechanical energy

Answer: b

19 - Which of the following statements are true with regard to resistance?
a) Resistance is directly proportional to length of the wire
b) Resistance is directly proportional to area of cross section of the wire
c) Resistance is inversely proportional to the length of the wire
d) All the statements are false

Answer: a

20 - The reciprocal of resistivity is________
a) Conductance
b) Resistance
c) Conductivity
d) Impedance

Answer: c

21 - The resistance of insulators __________
a) Increases with increase in temperature
b) Decreases with increase in temperature
c) Remains the same with increase in temperature
d) Becomes zero with increase in temperature

Answer: b

22 - What is the unit of temperature coefficient?
a) ohm/centigrade
b) ohm-centigrade
c) centigrade-1
d) centigrade

Answer: c

23 - The rise or fall in resistance with the rise in temperature depends on________
a) The property of the conductor material
b) The current in the metal
c) Both the given options
d) Does not depend on any factor

Also Read - MCQ on Control System for Electrical Engineering

Answer: a

24 - Materials having resistance almost equal to zero is_______
a) Semi-conductor
b) Conductor
c) Superconductors
d) Insulators

Answer: c
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