Basic knowledge about Voltage, Current, Resistance, Power, Power Efficiency, Power Factor.

What is voltage?

It is a quantitative expression of the potential difference in charge between two points in an electrical field. Voltage is also called electromotive force.

Greater voltage means the greater flow of electrical current through a conducting or semi-conducting medium used for a given resistance to the flow. Voltage is shown by letter “V” or “E”. The standard unit is the “volt”. One volt will drive one coulomb (6.24 x 1018) charge carriers, for example electrons, through a resistance of one ohm in one second.

What is current?

Current is flow through one side to another side, its carriers electrical charge usually electrons or electron-deficient atoms.  The letter “I” is indicate the symbol of current. The standard unit is the “ampere”, symbolized by “A”. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) in one second, basically current flows from quite positive points to comparatively negative points.

There are two types of current direct or alternating. Direct current (DC) flows in the same path by any means points in time. In an alternating current (AC), is charge carriers reverses way periodically.

What is resistance?

Resistance is a substance that opposes the flow of current in the wire.  It is represented by “R” of the capital letter. It measured unit is ohm which is represented by Greek letter “omega”. When an electric current of one ampere passes through a component across which a potential difference (voltage) of one volt exists, then the resistance of that component is one ohm.

What is power?

Power is the rate by the side of which electrical energy is converted to another form, for example motion, heat, or an electromagnetic field. It is defined the letter “P”. The standard unit the watt is symbolized by “W”. In utility circuits, the kilowatt (kW) is often specified instead; 1 kW = 1000 W.

What is power efficiency?

Power Efficiency is equal to the 100% ratio of the output power divided by the input power. It is called power efficiency.

η is the efficiency in percent (%).

Pin is the input power use in watts (W).

Pout is the output power or real work in watts (W).

η = 100% · Pout / Pin

What is power factor?

The power factor is equal to the true power”P” divided by the apparent power |S|. It is called power factor.

The power factor values in the range either 0 or 1.

When all the power is reactive power with no real power (usually inductive load) - the power factor is 0. & when all the power is real power with no reactive power (resistive load) - the power factor is 1.

PF = P (W) / |S (VA)|

PF - power factor.

P   - Real power in watts (W).

|S|   - apparent power in volt·amps (VA).