Unit of Electricity

Bookmark added to your notes.
View Notes
×

The standard unit of electricity is defined in a systematic way. First, the ampere is defined. After, the ampere comes charge and coulomb of an electron.

The SI units to measure the electric expressions of voltage, resistance and current are Volt (v), Ohm (Ω) and Ampere (A) respectively.

The electrical units for measurement of electric expressions are based on the International System (SI) of units. Other units are derived from this si unit of electricity.

The units are used in electric circuits, electronics and electric appliances to measure and describe their capacity from small to large.

The below mentioned table provides the necessary data of some standard electric units, their formulas and their respective component values.

Standard Electrical Units of Measure

Electrical Parameter

Measuring Unit

Unit/Symbol

Formula

Voltage

Volt

V or E

V = I×R

Resistance

Ohm

R or Ω

R = V÷I

Current

Ampere

I or i

I = V÷R

Capacitance

Farad

C

C = Q÷V

Conductance

Siemen

G

G = 1÷R

Charge

Coulomb

C

Q = C×V

Power

Watts

W

P = V×I or I²×R

Inductance

Henry

L/H

VL = -L(di/dt)

Frequency

Hertz

Hz

f = 1÷T

Impedance

Ohm

Z

Z² = R²+X²


Standard Units (Multiples And Submultiples)

There are a huge range of electric values between a minimum value and a maximum value of a standard electric unit. For example, the resistance of a conductor can be low as 0.001 ohm and high as 100000 ohms. We can avoid writing multiple zeros while describing the values of the electric unit, if we use sub-multiples and multiple values of the standard unit. Below mentioned is a table with their names and abbreviation.

Prefix

Symbol

Multiplier

Power of ten

pico

1/1,000,000,000,000

p

1012

nano

1/1,000,000,000

n

109

micro

1/1,000,000

μ

106

mini

1/1,000

m

103

centi

1/100

c

100

none

1

none

10-2

kilo

1,000

k

10-3

Mega

1,000,000

M

10-6

Giga

1,000,000,000

G

10-9

Terra

1,000,000,000,000

T

10-12

 

Below mentioned is a set of points which describes the use of units or multiple of units of resistance, current and voltage.

● 1kV = 1 kilo-volt = 1,000 Volts.

● 1kΩ = 1 kilo-ohms = 1 thousand Ohms.

● 1mA = 1 milli-amp = one thousandths (1/1000) of an Ampere.

● 1kW = 1 kilo-watt = 1,000 Watts.

● 100uF = 100 microfarads = 100 millionths (100/1,000,000) of a Farad.

● 1MHz = 1 mega-hertz = one million Hertz.

While converting one prefix to another, we have to multiply or divide the difference between the two values.


What Are The Basic Units Of Electricity?

Voltage/Volts (V) - The amount of work required to move an electric charge from one point to another is called voltage.

Current (I)/Amps (A) - Current is defined as the amount of charge (or electrons) passing through a circuit per unit time.

●  Resistance (R) /Ohms (O) - Resistance is the opposition offered to the flow of current in a circuit.

●  Power (P)/Watts (W) - Power is defined as the product of the work required and the number of electrons passing through the circuit per unit time.

(Image to be added soon)


Other Electricity Units

Just like the standard units, there are other units which are used to denote the values and quantities. They are:

Wh – The Watt-Hour is defined as the amount of electric energy consumed by an electric circuit over a given time duration. For example, a normal electric bulb consumes 100 watts of power per hour.

dB – The Decibel is one tenth unit of Bel (symbol B). It is used to represent gain in voltage, power or current.

 θ – Phase Angle. It is the difference (in degrees) between the voltage waveform and the current waveform, which have the same time period. It is a time difference which depends upon the circuit element. Its value can be “leading” or “lagging”. It is also measured in radians.

●   ω – Angular Frequency, It is used in AC circuits to represent phase relation between two waveforms.

  τ – Time Constant, The Time Constant is a characteristic of an impedance circuit. It is the time taken by the output to reach 63.7% of its minimum or maximum value when subjected to step response input. It is a measure of time reaction.


Charge SI Unit

The SI unit of electric charge is coulomb. A coulomb is defined as an ampere second.

The Units of Electric Charge are Listed in The Table Mentioned Below

Name

Symbols

Context

Alternate Spellings

Prefixes

coulomb

C

SI

coulombs

SI

statcoulomb

statC

ESU

statcoulombs

SI

abcoulomb

abC

EMU

ab coulombs

SI

franklin

f

Standard

franklins

SI

electron

e

Atomic

electrons

SI

planck_charge

 

planck

planck_charges

 


These are the units of electric charge.


Do You Know?

There is nothing like “1 unit electricity”.

Throughout the world there is one type or another type of measurement which has been taken as a base amount of electric power. 1KWh is a mainly used unit of power. It is the amount of electric power consumed in 1 hour by an electric appliance of 1000 W (1KW).

FAQ (Frequently Asked Questions)

1. How to Convert 1MHz into kHz?

1 kHz is equal to one thousand (1,000,) hertz, and 1 MHz is equal to one million (1,000,000) hertz. So, one 1MHz is one thousand times larger than 1kHz. Then to convert megahertz into Kilo-hertz, we have to multiply megahertz by 1000 because 1 MHz is equal to 1000 kHz.

2. What is the Commercial Unit of Electricity?

The primarily applied commercial unit of electricity is kWh. It is the energy expended by a source of 1 KW in a time duration of one hour. It is not a standard unit in the formal system, but is used in electric appliances.

(Image to be added soon)

3. State The dB Ratio of An Input Voltage To An Output Voltage

The dB ratio of an input voltage (VIN) with respect to that of an output voltage (Vout) is expressed as 20log10(Vout/Vin). This value can either be positive (20dB) which represents gain or negative (-20dB) which represents loss, and a value of 0 represents unity i.e input = output expressed by 0 dB.

4. How Are Units Of Electricity Measured?

Electricity is measured by electric meters in kilowatt hours (kWh), or Units. Subtracting the old electricity meter reading from the current meter reading, gives the units of current used.