ELECTRONICS BASICS AND REFERENCE INFORMATION

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THE BASIC ELECTRONIC CONCEPTS



Electronics engineering deals with the design, analysis and applications of electronic circuits. A circuit is a collection of components connected by conductors that forms a closed path through which an electric current can flow to achieve a particular functionality.
Electric current is the rate of charge flow past a given point in an electric circuit: I=Q/t, where I - current in amps, Q- charge in coulomb, t - time in seconds. Charge is the fundamental property of a matter carried by some elementary particles, which determines their electromagnetic interaction. This property is measured in coulombs (C), and it exhibits two states, positive and negative. In classical physics the charge of any system, body, or particle is an integer multiple of the elementary charge e, which is equal to 1.602×10−19 coulombs. By convention, the proton has a charge of e, and the electron has a charge of -e. Although electric current in conductors is produced by the motion of electrons, it has long been the convention to take the direction of electric current as if it were the positive charges which are moving.

The flow of the charges is influenced by electric field. When a charged particle moves in the field from point A to point B, a specific work done on this particle by electrical forces and as a result its potential energy changes. This work per unit charge is called voltage: V=W/Q. Voltage is measured in volts (1 V is 1 joule per coulomb). Since power in general is work per unit time, the amount of power transfer (i.e., rate at which electric energy is transformed by the flow of current) is then given by the equation P = W/t = V×Q/t = V×I.

BASIC ELECTRONIC COMPONENTS



Basic components used in electronics are classified into passive (such as resistors, capacitors and inductors) or active (such as transistors and diodes). For the purpose of circuit design and analysis we normally replace real objects by so-called lumped circuit abstractions. These abstractions are idealized elements that capture some essential aspects of real device operation and that allows us to view a circuit as a set of discrete or "lumped" elements.
An ideal resistor is defined as an element for which the ratio of voltage divided by current is constant. This constant ratio is called resistance: R=V/I. A resistor is dissipative element: it does not store energy, but simply removes it from the circuit.

ELECTRICAL UNITS SUMMARY
QUANTITY SYMBOL NAME OF
THE UNIT		 RELATIONSHIPS WITH
OTHER QUANITIES
Capacitance C farad (F) Q/V
Charge Q coulomb (C) I×t
Conductance G siemens (S) I/V or 1/R
Current I amper (A) Q/t
Inductance L Henry (H) V×Δt/ΔI
Voltage V volt (V) I×R
Resistance R ohm (Ω) V/I
Note: t- time (in seconds)
A capacitor is a device consisting of two conductors separated by a dielectric. When a voltage is applied to a capacitor, certain charges with equal value and opposite signs will appear on these conductors so that the potential difference produced by these charges will be equal to the applied voltage. The capacitance C is defined as the ratio of the charge magnitude on each conductor to the voltage: C = Q/V, where C is in farads (F). An ideal capacitor does not pass a direct current, while allowing AC to pass:
i(t)=C×ΔV(t)/Δt.

An inductor is an two-terminal element resisting any change of electric current through it. An ideal inductor has zero resistance and in a steady state mode has zero DC voltage across its terminals. When AC current passes through an inductor, the AC voltage that appears across its terminals is due to its own magnetic field and Faraday's law of electromagnetic induction: V(t)=L×Δi(t)/Δt.

Below you find additional infomation on electronics, circuit design and analysis as well as learning and career resources.

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BASIC ELECTRONIC
CIRCUIT DESIGN
AND ANALYSIS

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