Definition of electronics: Electronics is the branch of science deals with the study That of flow and control of electrons (electricity) and the study of Their behavior and effects in vacuums, gases, and Semiconductors, and with devices using Such electrons. This control of electrons is accomplished by devices that resist, carry, select, steer, switch, store, manipulate, and exploit the electron. This control of electrons is accomplished by devices That resist, carry, select, steer, switch, store, Manipulate, and exploit the electron.
Some of the basic electrical units and definitions are mentioned below: Some of the basic electrical units and definitions are Mentioned below:
Passive: Capable of operating without an external power source. Passive: Capable of operating without an external power source. Typical passive components are resistors, capacitors, inductors and diodes (although the latter are a special case). Typical passive components are resistors, capacitors, inductors and diodes (although the latter are a special case).
Active: Requiring a source of power to operate. Active: Requiring a source of power to operate. Includes transistors (all types), integrated circuits (all types), TRIACs, SCRs, LEDs, etc. Includes transistors (all types), integrated circuits (all types), triacs, SCRs, LEDs, etc.
DC: Direct Current. DC: Direct Current. The electrons flow in one direction only. The electrons flow in one direction only. Current flow is from negative to positive, although it is often more convenient to think of it as from positive to negative. Current flow is from negative to positive, although it is more convenient to Often think of it as from positive to negative. This is sometimes referred to as "conventional" current as opposed to electron flow. This is Sometimes Referred to as "conventional" as opposed to electron current flow.
AC: Alternating Current. AC: Alternating Current. The electrons flow in both directions in a cyclic manner - first one way, then the other. The electrons flow in both directions in a cyclic manner - first one way, then the other. The rate of change of direction determines the frequency, measured in Hertz (cycles per second). The rate of change of direction Determines the frequency, Measured in Hertz (cycles per second).
Frequency: Unit is Hertz, Symbol is Hz, old symbol was cps (cycles per second). Frequency: The unit is Hertz, Symbol is Hz, was the old symbol cps (cycles per second). A complete cycle is completed when the AC signal has gone from zero volts to one extreme, back through zero volts to the opposite extreme, and returned to zero. A complete cycle is completed when the AC signal has gone from zero volts to one extreme, back through zero volts to the opposite extreme, and returned to zero. The accepted audio range is from 20Hz to 20,000Hz. The accepted audio range is from 20Hz to 20,000 Hz. The number of times the signal completes a complete cycle in one second is the frequency. The number of times the signal completes a complete cycle in one second is the frequency.
Voltage: Unit is Volts, Symbol is V or U, old symbol was E . Voltage: The unit is Volts, Symbol is V or U, the old symbol was E. Voltage is the "pressure" of electricity, or "electromotive force" (hence the old term E). Voltage is the "pressure" of electricity, or "electromotive force" (Hence the old term E). A 9V battery has a voltage of 9V DC, and may be positive or negative depending on the terminal that is used as the reference. A 9V battery has a voltage of 9V DC, and may be positive or negative depending on the terminal is used as the That reference. The mains has a voltage of 220, 240 or 110V depending where you live - this is AC, and alternates between positive and negative values. The mains has a voltage of 220, 240 or 110V depending where you live - this is AC, and alternates positive and negative values Between. Voltage is also commonly measured in millivolts (mV), and 1,000 mV is 1V. Voltage is also commonly Measured in millivolts (mV), and 1.000 mV is 1V. Microvolts (uV) and nanovolts (nV) are also used. Microvolts (uV) and nanovolts (nV) are also used.
Current: Unit is Amperes (Amps), Symbol is I . Current: Unit is amperes (Amps), Symbol is I. Current is the flow of electricity (electrons). Current is the flow of electricity (electrons). No current flows between the terminals of a battery or other voltage supply unless a load is connected. No current flows Between the terminals of a battery or other voltage supply unless a load is connected. The magnitude of the current is determined by the available voltage, and the resistance (or impedance) of the load and the power source. The magnitude of the current is determined by the available voltage, and the resistance (or impedance) of the load and the power source. Current can be AC or DC, positive or negative, depending upon the reference. Current can be AC or DC, positive or negative, depending upon the reference. For electronics, current may also be measured in mA (milliamps) - 1,000 mA is 1A. For electronics, may also be Measured current in mA (milliamps) - 1.000 mA is 1A. Nanoamps (nA) are also used in some cases. Nanoamps (nA) are also used in some cases.
Resistance: Unit is Ohms, Symbol is R or Ω . Resistance: Unit is Ohms, Symbol is R or Ω. Resistance is a measure of how easily (or with what difficulty) electrons will flow through the device. Resistance is a measure of how easily (or with what difficulty) electrons will flow through the device. Copper wire has a very low resistance, so a small voltage will allow a large current to flow. Copper wire has a very low resistance, so a small voltage will allow a large current to flow. Likewise, the plastic insulation has a very high resistance, and prevents current from flowing from one wire to those adjacent. Likewise, the plastic has a very high insulation resistance, and prevents current from flowing from one wire to Those adjacent. Resistors have a defined resistance, so the current can be calculated for any voltage. Resistors have a defined resistance, so the current can be calculated for any voltage. Resistance in passive devices is always positive (ie > 0) Resistance in passive devices is always positive (ie> 0)
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Capacitance: Unit is Farads, Symbol is C. Capacitance: Unit is Farads, Symbol is C. Capacitance is a measure of stored charge. Capacitance is a measure of stored charge. Unlike a battery, a capacitor stores a charge electrostatically rather than chemically, and reacts much faster. Unlike a battery, a capacitor stores a charge electrostatically rather than Chemically, and reacts much faster. A capacitor passes AC, but will not pass DC (at least for all practical purposes). A capacitor passes AC, but will not pass DC (at least for all practical purposes). The reactance or AC resistance (called impedance) of a capacitor depends on its value and the frequency of the AC signal. The reactance or AC resistance (called impedance) of a capacitor depends on its value and the frequency of the AC signal. Capacitance is always a positive value. Capacitance is always a positive value.
Inductance: Unit is Henrys, Symbol is H or L (depending on context). Inductance: Unit is Henrys, Symbol is H or L (depending on context). Inductance occurs in any piece of conducting material, but is wound into a coil to be useful. Inductance Occurs in any piece of conducting material, but is wound into a coil to be useful. An inductor stores a charge magnetically, and presents a low impedance to DC (theoretically zero), and a higher impedance to AC dependent on the value of inductance and the frequency. An inductor stores charge a magnetically, and presents a low impedance to DC (theoretically zero), and a higher impedance to AC dependent on the value of inductance and the frequency. In this respect it is the electrical opposite of a capacitor. In this respect it is the electrical opposite of a capacitor. Inductance is always a positive value. Inductance is always a positive value. The symbol "Hy" is sometimes used in (guess where :-) ... The symbol "Hy" Sometimes is used in (guess where :-) ... the US. the U.S.. There is no such symbol. There is no such symbol.
Impedance: Unit is Ohms, Symbol is Ω or Z. Impedance: Unit is Ohms, Symbol is Ω or Z. Unlike resistance, impedance is a frequency dependent value, and is specified for AC signals. Unlike resistance, impedance is a frequency dependent value, and is specified for AC signals. Impedance is made up of a combination of resistance, capacitance, and/ or inductance. Impedance is made up of a combination of resistance, capacitance, and / or inductance. In many cases, impedance and resistance are the same (a resistor for example). In many cases, impedance and resistance are the same (a resistor for example). Impedance is most commonly positive (like resistance), but can be negative with some components or circuit arrangements. Impedance is most commonly positive (like resistance), but can be negative with some components or circuit arrangements.
Decibels: Unit is Bel, but because this is large, deci-Bels (1/10th Bel) are used), Symbol is dB. Decibels: Unit is Bel, but Because this is large, deci-Bels (1/10th of a Bel) are used), Symbol is dB. Decibels are used in audio because they are a logarithmic measure of voltage, current or power, and correspond well to the response of the ear. Decibels are used in audio Because They are a logarithmic measure of voltage, current or power, and correspond well to the response of the ear. A 3dB change is half or double the power (0.707 or 1.414 times voltage or current respectively). A 3dB change is half or double the power (0707 or 1414 times the voltage or current respectively). Decibels will be discussed more thoroughly in a separate section. Decibels will be Discussed more thoroughly in a separate section.
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