#### Electronics, Physics tutorial

Introduction:

Electronics is branch of science which deals with study of flow and control of electrons (electricity) and study of their behavior and effects in vacuums, gases, and semiconductors, and with devices using such electrons. This control of electrons is achieved by devices which resist, choose, steer, carry, switch, store, manipulate, and exploit electron.

Passive: Capable of operating without the external power source. Typical passive components are capacitors, resistors, inductors and diodes.

Active: Requiring the source of power to operate. Comprises transistors (all kinds), integrated circuits (all kinds), SCRs, LEDs, TRIACs, etc.

DC: Direct Current. Electrons flow in only one direction.  Current flow is from negative to positive, though it is frequently more convenient to think of it as from positive to negative.  This is at times referred to as conventional current as opposed to electron flow.

AC: Alternating Current. Electrons flow in both directions in the cyclic manner - first one way, then other. Rate of change of direction finds frequency, calculated in Hertz (cycles per second).

Frequency: Unit is Hertz, Symbol is Hz. The complete cycle is completed when AC signal has gone from zero volts to one extreme, back through zero volts to opposite extreme, and returned to zero.  Accepted audio range is from 20Hz to 20,000Hz.  Number of times the signal completes the complete cycle in one second is frequency.

Voltage: Unit is Volts, Symbol is V or U. Voltage is pressure of electricity, or electromotive force (therefore old term E).  9V battery has the voltage of 9V DC, and may be positive or negative depending on terminal which is utilized as reference.  Mains has a voltage of 220, 240 or 110V depending where you live - this is AC, and alternates between positive and negative values.  Voltage is also usually calculated in millivolts (mV), and 1,000 mV is 1V.  Microvolts (uV) and nanovolts (nV) are also utilized.

Current: Unit is Amperes (Amps), and Symbol is I. Current is a flow of electricity (electrons).  Current does not flow between terminals of battery or other voltage supply unless the load is linked.  Magnitude of current is computed by available voltage, and resistance (or impedance) of load and power source.  Current can be AC or DC, positive or negative, depending on reference.  For electronics, current may also be calculated in mA (milliamps) - 1,000 mA is 1A.  Nanoamps (nA) are also utilized in some cases.

Resistance: Unit is Ohms, Symbol is R or Ω. Resistance is the measure of how easily electrons will flow through device.  Copper wire has the very low resistance, so small voltage will permit the large current to flow.  Similarly, plastic insulation has the very high resistance, and prevents current from flowing from one wire to those adjacent.  Resistors have the defined resistance, so current can be computed for any voltage.  Resistance in passive devices is always positive (i.e. > 0)

Difference between Electronic and Electric:

Electric is usually acceptable to use terms electric and electrical interchangeably. Fundamentally, word electric will function as the way of qualifying flow of electricity as it associates to specific event. For instance, if fire starts because of problem with wiring in the building, event can be explained as electric or electrical fire, caused by electric or electrical wiring. Use of electric recognizes source of power which serves to create the logical effect when conducted through the process or device.

On the contrary, electronic is the term which is descriptive of devices which are powered by electricity. The electronic device is frequently constructed utilizing one or more electric elements which make it possible to manage flow of electricity into device. The television is a good example, as it is partly composed of the series of individual electric components which help to conduct flow of electricity. In similar manner, desktop and laptop computers are electronic in nature. Handheld devices like cell phones are also electronic, during operating with use of an electric component - a battery.

Basic Electronic Components:

The functions of each of the basic electronic components are given below:

Resistors: Resistor is the component which resists flow of current. It is one of the most basic components utilized in electronic circuits. Resistors come in the variety of resistance values (how much they resist current, calculated in units known as ohms and designated by symbol Ω and power ratings (how much power they can manage without burning up, calculated in watts).

Capacitors: Next to resistors, capacitors are possibly the second most normally utilized component in electronic circuits. Capacitor is the device which can temporarily store the electric charge. Capacitors come in numerous different varieties, two most common being ceramic disk and electrolytic. Amount of capacitance of the given capacitor is generally calculated in microfarads, abbreviated μF.

Diodes: Diode is the device which allows current flow in just one direction. Diode has two terminals, known as anode and cathode. Current will flow through diode only when positive voltage is applied to anode and negative voltage to cathode. If the voltages are reversed, current won't flow.

Light-Emitting Diodes: Light-emitting diode (or LED) is the special kind of diode which emits light when current passes through it.

Transistors: Transistor is the three-terminal device in the voltage applied to one of the terminals (known as base) can manage current which flows across other two terminals (known as collector and emitter). Transistor is one of the most significant devices in electronics.

Integrated Circuits: Integrated circuit is the special component which has the entire electronic circuit, complete with diodes, transistors, and other elements, all photographically etched onto the small piece of silicon. Integrated circuits are building blocks of modern electronic devices like computers and cell phones.

Application of Electronics:

Electronics has made wonderful development during last few decades and our day to day life engages use of electronic devices. Electronics has played the major role in every sphere of our life; this can be proved with the application of electronics given below:

Entertainment and Communication: Accessibility of economical and fast way of communication paves way for progress of the country. Few decades ago, major application of electronics was in field of telephony and telegraphy. Now, with the help of radio waves we can transmit any message from one place to another, without the use of wires. Radio and TV broadcasting offers a way of both entertainment as well as communication. Today, Electronics gadgets are extensively utilized for entertainment.

Defense Applications: Defense applications are totally handled by electronic circuits. RADAR that is Radio Detection and Ranging is the most significant development in electronics field. With the aid of radar it is probable to detect and find exact location of enemy aircraft. Radar and anti craft guns can be related by the automatic control system to make the complete unit.

Industrial Application: Electronics circuits are extensively being utilized in industrial applications like quality, control of thickness, weight and moisture content of the material. Electronic amplifier circuits are utilized to amplify signals and therefore control operations of automatic door openers, power systems and safety devices. Electronically handled systems are utilized for heating and welding in industry. Most significant industrial application is that power stations that produce thousands of megawatts of electricity are handled by minute electronic devices and circuits.

Medical Services: Electronics systems are being utilized by Doctors and scientists in diagnosis and treatment of different diseases. X-rays, ECG, Short eave diathermy units and oscillographs are some instruments that have been utilized so far in medical science. Use of electronics in medical science has developed so tremendously and is helpful in saving life of mankind from various sufferings.

Instrumentation: Electronics instruments like cathode-ray oscilloscopes, frequency counters, signal generators, strain gauges are of great assistance in for accurate measurement of different quantities. Lacking these electronic instruments research laboratory is not complete.

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