Wednesday, January 25, 2012

Basic Concept of Electric Circuit

Subdivision in Electrical Engineering

Communication systems
Computer systems
Control systems
Power systems
Signal processing

Electric Current

The time rate of flow of electrical charge passing through a predetermined area of a conductor.
The unit is in Ampere [A]
Constant current of 1[A]=1[C/s]

Fluid Flow Analogy

Electrical circuits are analogous to fluid flow systems.
Battery = Pump
Conductors (Copper wires)=pipes
Current=Flow rate of the fluid
Voltage=Pressure difference between points in the fluid circuit

Kirchhoff’s Current Law(KCL)

A node in an electrical circuit is a point at which two ore more circuit elements are joined together.
The net current entering a node is zero.
Current entering---------- (+)
Current leaving------------ (-)
Another way to state KCL: The sum of currents entering a node equals the sum of currents leaving a node.
No current is lost around the closed circuit
The sum of the currents at a node must equal to zero

How voltage, current, and resistance relate

An electric circuit is formed when a conductive path is created to allow free electrons to continuously move. This continuous movement of free electrons through the conductors of a circuit is called a current, and it is often referred to in terms of "flow," just like the flow of a liquid through a hollow pipe.

The force motivating electrons to "flow" in a circuit is called voltage. Voltage is a specific measure of potential energy that is always relative between two points. When we speak of a certain amount of voltage being present in a circuit, we are referring to the measurement of how much potential energy exists to move electrons from one particular point in that circuit to another particular point. Without reference to twoparticular points, the term "voltage" has no meaning.

Free electrons tend to move through conductors with some degree of friction, or opposition to motion. This opposition to motion is more properly called resistance. The amount of current in a circuit depends on the amount of voltage available to motivate the electrons, and also the amount of resistance in the circuit to oppose electron flow. Just like voltage, resistance is a quantity relative between two points. For this reason, the quantities of voltage and resistance are often stated as being "between" or "across" two points in a circuit.
To be able to make meaningful statements about these quantities in circuits, we need to be able to describe their quantities in the same way that we might quantify mass, temperature, volume, length, or any other kind of physical quantity. For mass we might use the units of "kilogram" or "gram." For temperature we might use degrees Fahrenheit or degrees Celsius. Here are the standard units of measurement for electrical current, voltage, and resistance:
The "symbol" given for each quantity is the standard alphabetical letter used to represent that quantity in an algebraic equation. Standardized letters like these are common in the disciplines of physics and engineering, and are internationally recognized. The "unit abbreviation" for each quantity represents the alphabetical symbol used as a shorthand notation for its particular unit of measurement. And, yes, that strange-looking "horseshoe" symbol is the capital Greek letter Ω, just a character in a foreign alphabet (apologies to any Greek readers here).

Each unit of measurement is named after a famous experimenter in electricity: The amp after the Frenchman Andre M. Ampere, the volt after the Italian Alessandro Volta, and the ohm after the German Georg Simon Ohm.

The mathematical symbol for each quantity is meaningful as well. The "R" for resistance and the "V" for voltage are both self-explanatory, whereas "I" for current seems a bit weird. The "I" is thought to have been meant to represent "Intensity" (of electron flow), and the other symbol for voltage, "E," stands for "Electromotive force." From what research I've been able to do, there seems to be some dispute over the meaning of "I." The symbols "E" and "V" are interchangeable for the most part, although some texts reserve "E" to represent voltage across a source (such as a battery or generator) and "V" to represent voltage across anything else.

All of these symbols are expressed using capital letters, except in cases where a quantity (especially voltage or current) is described in terms of a brief period of time (called an "instantaneous" value). For example, the voltage of a battery, which is stable over a long period of time, will be symbolized with a capital letter "E," while the voltage peak of a lightning strike at the very instant it hits a power line would most likely be symbolized with a lower-case letter "e" (or lower-case "v") to designate that value as being at a single moment in time. This same lower-case convention holds true for current as well, the lower-case letter "i" representing current at some instant in time. Most direct-current (DC) measurements, however, being stable over time, will be symbolized with capital letters.

One foundational unit of electrical measurement, often taught in the beginnings of electronics courses but used infrequently afterwards, is the unit of the coulomb, which is a measure of electric charge proportional to the number of electrons in an imbalanced state. One coulomb of charge is equal to 6,250,000,000,000,000,000 electrons. The symbol for electric charge quantity is the capital letter "Q," with the unit of coulombs abbreviated by the capital letter "C." It so happens that the unit for electron flow, the amp, is equal to 1 coulomb of electrons passing by a given point in a circuit in 1 second of time. Cast in these terms, current is the rate of electric charge motion through a conductor.

As stated before, voltage is the measure of potential energy per unit charge available to motivate electrons from one point to another. Before we can precisely define what a "volt" is, we must understand how to measure this quantity we call "potential energy." The general metric unit for energy of any kind is the joule, equal to the amount of work performed by a force of 1 newton exerted through a motion of 1 meter (in the same direction). In British units, this is slightly less than 3/4 pound of force exerted over a distance of 1 foot. Put in common terms, it takes about 1 joule of energy to lift a 3/4 pound weight 1 foot off the ground, or to drag something a distance of 1 foot using a parallel pulling force of 3/4 pound. Defined in these scientific terms, 1 volt is equal to 1 joule of electric potential energy per (divided by) 1 coulomb of charge. Thus, a 9 volt battery releases 9 joules of energy for every coulomb of electrons moved through a circuit.

These units and symbols for electrical quantities will become very important to know as we begin to explore the relationships between them in circuits. The first, and perhaps most important, relationship between current, voltage, and resistance is called Ohm's Law, discovered by Georg Simon Ohm and published in his 1827 paper, The Galvanic Circuit Investigated Mathematically. Ohm's principal discovery was that the amount of electric current through a metal conductor in a circuit is directly proportional to the voltage impressed across it, for any given temperature. Ohm expressed his discovery in the form of a simple equation, describing how voltage, current, and resistance interrelate:
In this algebraic expression, voltage (E) is equal to current (I) multiplied by resistance (R). Using algebra techniques, we can manipulate this equation into two variations, solving for I and for R, respectively:
Let's see how these equations might work to help us analyze simple circuits:
In the above circuit, there is only one source of voltage (the battery, on the left) and only one source of resistance to current (the lamp, on the right). This makes it very easy to apply Ohm's Law. If we know the values of any two of the three quantities (voltage, current, and resistance) in this circuit, we can use Ohm'sLaw to determine the third.
In this first example, we will calculate the amount of current (I) in a circuit, given values of voltage (E) and resistance (R):
What is the amount of current (I) in this circuit?
In this second example, we will calculate the amount of resistance (R) in a circuit, given values of voltage (E) and current (I):
What is the amount of resistance (R) offered by the lamp?
In the last example, we will calculate the amount of voltage supplied by a battery, given values of current (I) and resistance (R):
What is the amount of voltage provided by the battery?

Ohm's Law is a very simple and useful tool for analyzing electric circuits. It is used so often in the study of electricity and electronics that it needs to be committed to memory by the serious student. For those who are not yet comfortable with algebra, there's a trick to remembering how to solve for any one quantity, given the other two. First, arrange the letters E, I, and R in a triangle like this:
If you know E and I, and wish to determine R, just eliminate R from the picture and see what's left:
If you know E and R, and wish to determine I, eliminate I and see what's left:
Lastly, if you know I and R, and wish to determine E, eliminate E and see what's left:
Eventually, you'll have to be familiar with algebra to seriously study electricity and electronics, but this tip can make your first calculations a little easier to remember. If you are comfortable with algebra, all you need to do is commit E=IR to memory and derive the other two formulae from that when you need them!
  • Voltage measured in volts, symbolized by the letters "E" or "V".
  • Current measured in amps, symbolized by the letter "I".
  • Resistance measured in ohms, symbolized by the letter "R".
  • Ohm's Law: E = IR ; I = E/R ; R = E/I


A market with a large number of buyers and sellers, such that no single buyer or seller is able to influence the price or control any other aspect of the market. That is, none of the participants have significant market control. A competitive market achieves efficiency in the allocation of scarce resources if no other market failures are present.
A competitive market is a market with a sufficient number of both buyers and sellers such than no one buyer or seller is able to exercise control over the market or the price. Efficiency is achieved because competition among buyers forces buyers to pay their maximum demand price and competition among sellers forces sellers to charge their minimum supply price for the given quantity exchanged.

Working the Market Model

Competitive Market
Competitive Market
The market model presented here depicts a typical competitive market that has achievedequilibrium. The market demand curve is labeled D and the marketsupply curve is labeled S. Competition among buyers forces the market price up to the maximum demand price on the demand curve. Competition among sellers forces the market price down to the minimum supply price on the supply curve. With competition among both buyers and sellers, the market price is simultaneously on both the demand curve and the supply curve.
This result is illustrated by the market equilibrium achieved at price Po and quantity Qo. The competitive forces of demand and supply automatically generate this market equilibrium. If the going market price is higher or lower than Po, creating a shortage or surplus, then competitive forces eliminate the imbalance and restores equilibrium.

The Invisible Hand of Efficiency

A competitive market is efficient because equilibrium is achieved where the demand price and supply are price equal.
  • Competition on the demand side forces buyers to buy a good at the maximum demand price that they are willing and able to pay. The demand price is the value society places on the good produced based on the satisfaction received.
  • Competition on the supply side forces sellers to sell the good at the minimum supply price that they are willing and able to accept. The supply price is the opportunity cost of production, which is the value of goods NOT produced.
Equality between the demand and supply prices means that the economy cannot generate any greater satisfaction by producing more of one good and less of another.
Competitive markets are the cornerstone of capitalism and a market-oriented economy. They efficiently address the scarcity problem and answer the three questions of allocation automatically (as if guided by aninvisible hand) with little or no government intervention.

Uncompetitive Markets

The real world contains some markets that come close to this competitive ideal and other markets that fall short. These real world markets can be grouped into three distinct market structures.
  • Monopolistic/Monopsonistic Competition: The most competitive real world markets are termed monopolistic competition or monopsonistic competition, depending on whether the focus is on the sellers (monopolistic) or the buyers (monopsonistic).
  • Oligopoly/Oligopsony: Real world markets with a modest amount of competition, but not a lot, are termed oligopoly or oligopsony, depending on whether the focus is on the sellers (oligopoly) or the buyers (oligopsony).
  • Monopoly/Monopsony: Real world markets that have no competition are termed monopoly, if there is only one seller, or monopsony, if there is only one buyer.

Other Market Failures

Competitive markets achieve an efficient allocation of resources as long as other market failures are not present. The lack of competition, also termed market control, is one key market failure. Three noted market failures are externalities, public goods, and imperfect information.
  • Externalities arise if the demand price does not fully reflect the value generated by the good or if the supply price does not fully reflect the opportunity cost production. As a result, the market equilibrium does not include all of the information about value and cost needed to achieve efficiency.
  • Public goods are goods characterized by nonrival consumption and the inability to exclude nonpayers. The use of the good by one does not impose a cost on others and no one can be prevented from consuming the good.
  • Imperfect information occurs if buyers or sellers do not know as much about the good as they should for an efficient allocation. In other words, buyers are not aware of the full value they obtain from consuming the good or sellers are not aware of all opportunity cost incurred in production.

Malaysian Federal Roads System

Malaysian Federal Roads System (MalaySistem Laluan Persekutuan Malaysia), is the main national road network in Malaysia. All Federal Roads in Malaysia are under the purview of Ministry of Works (MOW). According to Minister's Function Act 1969, MOW responsible to plan, build and maintain all Federal Roads gazetted under the Federal Road Act 1959. However, most of the Federal roads' projects was built and maintained by the Malaysian Public Works Department (JKR) which are also one of the implementing agency under the MOW (with exception of Sabah and Sarawak, whereby JKR in these two states is under respective state government).


Most of the federal roads in Peninsular Malaysia were built during the British colonial era before 1957. At that time, the British government built the roads in order to enable them to transport goods and commodities easier.
In Sabah, most of the federal roads were built during the occupation of British North Borneo under North Borneo Chartered Companyadministration, and unlike most federal roads in Peninsular Malaysia which uses only numbers to label federal roads, Sabah federal road codes begin with the letter A followed by route number.
However, in Sarawak, no road network system was developed during the rule of White Rajah Brooke dynasty. As a result, right after Sarawak joined the federation of Malaysia on 16 September 1963, the federal government of Malaysia began to build a road network system connecting Sarawak to Sabah, known as Pan Borneo Highway.

Federal road standards

Malaysian federal road shield


The total length of federal roads is 49,935 km (31,028 mi).
Federal routes are labeled with only numbers for example Federal Route Jkr-ft1.png while state routes are labeled with the state code letter followed by assigned numbers, for example Route J32Jkr-ft--.png is aJohor state road. However, federal route numbers can also be added with the prefix, which is normally used by JKR and Malaysian police. For example Federal Route Jkr-ft1.png can also be written as Federal Route Both federal and state roads have blue road signs and the text colour is white.
Most of the federal roads in Malaysia are 2-lane roads. Malaysia implements a right-hand driving system where drivers drive on the left side of the road. However, there are in certain places where additional lanes are available. In town areas, federal roads may become 4-lane roads to increase traffic capacity. In hilly areas, additional third climbing lane is available for slower vehicles such as buses and lorries.
Some federal roads may have motorcycle lanes. On Malaysian federal roads, the motorcycle lanes are placed at the extreme left side of each direction and only separated from the main lanes by black-and-white stripes to enable motorcyclists to overtake slower motorcycles and to turn right to exit the road.
Some expressways in Malaysia such as Federal Highway and Skudai Highway are federally funded, therefore all federally funded expressways are also classified as federal roads.
Nearly all federal roads are paved with typical tarmac except Skudai-Pontian Highway which is paved with concrete from Universiti Teknologi Malaysia interchange to Taman Sri Pulai junction and Sitiawan-Batak Rabit road (Federal route Jkr-ft5.png) from Sitiawan to Kota Setia. Meanwhile at Federal Highway linking Klang to Kuala Lumpur, the section of the highway from Subang Jaya to Kota Darul Ehsan near Petaling Jaya are paved with asphalt.
Sarawak has some of the most extensive federal road network in Malaysia. All federal roads in Sarawak is connecting main divisions with exception of Mukah division. As for Kapit division, the only federal road serving this division is Jalan Bakun (starting from KM 95 - KM 120). Coastal road of Bintulu-Miri is a still in dispute between federal government and state government right of maintenance. It is due to the construction is federal funded, but the compensation and acquisition of land are from Sarawak state government. No federal roads are isolated from the network unlike state roads. Uniquely in Sarawak, federal road network is adjoined internationally to Brunei highway atSungai Tujuh (Miri) with Kuala Belait (Brunei), Tedungan (Limbang) with Kuala Lurah (Brunei), Limbang with Puni (Brunei), Lawas with Labu (Brunei) and also to Indonesian road network at Tebedu (Serian district) with Entikong (Kalimantan BaratIndonesia).
Malaysian federal roads are subject to the rural highway standard adopted by Malaysian Public Works Department (JKR), ranging from R1 and R1a (minor roads at villages and FELDA settlements with no access control and low speed limits) to R5 (federal roads or highways with limited access control and speed limits up to 90 km/h). R6 standard is exclusive for high-speed (up to 110 km/h) expressways with full access control.

Type of federal roads and route number categories

ExamplesInformationNumber digits
Main federal route numbers001 - 249
Institutional facilities federal roads250 - 479
EXIT 226Federal road exit numbersEXIT 201 - EXIT 299
Main federal route numbers
1-1 - 1-59
3-1 - 3-99
Main federal route numbers
(Sabah; old numbering system)
A01 - A99
Main federal route numbers
700 - 799
FELDA/FELCRA federal route numbers1000 - 1999
2000 - 2999
Jkr-ft3214.pngIndustrial federal route numbers3000 - 3999

Main federal roads

Mostly found at Peninsula MalaysiaSabah and Sarawak.

FELDA/FELCRA federal roads

Mostly found at FELDA and FELCRA settlements in Peninsula Malaysia only. The road was built by FELDA or FELCRA and JKR.
In Sarawak, federal roads for FELDA is in Lundu and for SALCRA is in Sarikei.

Industrial federal roads

Mostly found at the industrial areas in Peninsula Malaysia only.
In Sarawak, there are two industrial federal roads, which are located at Pending Industrial Estate in Kuching and Kidurong Industrial Estate in Bintulu.

Institutional facilities federal roads

Mostly found at the entrance to the federal institutional facilities such as universitymilitary basessatelite earth stationsairportsTV andradio frequency stationstelecom exchange stationshospitals and tourist attractions.
For more information, please refer to Road signs in Malaysia articles or Malaysian Road Signs Information Brochure

Road design


StandardMax design
speed limit
lane width
Access controlApplication
JKR R61203.5FullExpressways under the administration of Malaysian Highway Authority (MHA)
JKR R51003.5PartialPrimary roads and partial access highways for the Federal JKR
JKR R4903.25PartialMain / secondary roads
JKR R3703.0PartialSecondary roads
JKR R2602.75NoneMinor roads

Note: JKR R2 is the minimum geometrical standard for 2-lane roads
JKR R140(5.0)*NoneSingle-lane minor roads (country lane)
JKR R1a40(4.5)*NoneSingle-lane roads (roads to restricted areas such as quarries)


StandardMax design
speed limit
lane width
Access controlApplication
JKR U61003.5FullExpressways under the administration of Malaysian Highway Authority (MHA)
JKR U5803.5PartialArterial roads and partial access municipal highways
JKR U4703.25PartialArterial / collector roads
JKR U3603.0PartialCollector roads / Local streets
JKR U2502.75NoneLocal streets

Note: JKR U2 is the minimum geometrical standard for 2-lane roads
JKR U140(5.0)*NoneSingle-lane street (in towns)
JKR U1a40(4.5)*NoneSingle-lane street (as in low-cost housing areas)
* - Total width of 2-way road

Malaysian federal roads as a part of Asian Highway Network

Asian Highway Network is an international project between Asian nations to develop their highway systems which will form the main routes in the Asian Highway network. There are 3 Asian Highway routes passing through Malaysia - Asian Highway Route 2 AH2 AH2Asian Highway Route 18 AH18 AH18 and Asian Highway Route 150 AH150 AH150.
The Malaysian section of Route AH2 AH2 consists of:-
The Malaysian section of Route AH18 AH18 consists of:-
The Malaysian section of Route AH150 AH150 consists of:-

Federal road maintenances

Before early 2000, the Malaysian federal roads were maintained by the Public Works Department. Beginning in 2000, the main contractors and maintenance company have the responsibility to maintain all federal roads in Malaysia.
Northern regionBelati Wangsa (M) Sdn Bhd
Central and east coast regionRoadcare (M) Sdn Bhd
Southern regionSelia Selenggara (M) Sdn Bhd; a subsidiary of the Ranhill Bersekutu (M) Sdn Bhd.
Federal Route Jkr-ft1.png is made by Selia Selanggara (M) Sdn BhdRoadcare (M) Sdn Bhd andRanhill Bersekutu (M) Sdn Bhd for Batu Pahat districts.
(including Federal Territory of Labuan)
Pembinaan Kekal Mewah Sdn Bhd
(Kuching, Samarahan, Sri Aman, Betong, Sarikei region)
PPES Works Sdn. Bhd; a subsidiary of the Cahya Mata Sarawak Berhad (CMSB) Group
(Sibu, Mukah, Bintulu region)
HCM Engineering Sdn. Bhd.; a subsidiary of the Protasco Berhad
(Miri, Limbang, Kapit region)
Endaya Construction Sdn. Bhd.; a subsidiary of the Encorp Properties Sdn. Bhd.


Speed limits

The default speed limit and National Speed Limits is 90 km/h (55 mph); however, a lower speed limit of 80 km/h (50 mph) has been implemented during festive seasons starting from the 2006 Hari Raya Aidilfitri as a preventive measure to reduce accidents during festive seasons. In town areas, the speed limit is reduced to 60 km/h (40 mph). Speed traps are also deployed by the Malaysian police at many places along the federal roads.

Related Posts with Thumbnails