Electronics Handbook/Conductor and Electricity

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Conductor and Electricity

Normally, Charges in Conductor drift randomly . When an Electric Source is connected to a conductor, The Electric Force will exert a Pressure on the charges to force charges to move in straight line causing a Current inside the conductor . The Presure of the Electric Source is called Voltage


Voltage is defined as The pressure of the Electricity Force to make charges in the conductor to move in straight line and calculated by the ratio of Work Done on an Electric Charge . Voltage is denoted as V measured in Volt v .

V = \frac{W}{Q}
1v = \frac{1J}{1C}


Current is defined as number of electric charges flow through an area of conductor in a period of Time . Current is calculated by the ratio of Electric Charge on Time . Current is denoted as I measured in Ampere A

I = \frac{Q}{t}
1A = \frac{1C}{1s}


Power is defined as Energy of a Work over Time. Power is calculated by the product of Voltage and Current . Power is denoted as P measured in Joule J or Volt Amp VA

E = \frac{W}{Q} \frac{Q}{t} = \frac{W}{t} = V I
1 J = 1v x 1A


Conductance is defined as the ratio of Current over Voltage . Conductance is denoted as Y measured in Siemen 1 / Ω

Y = \frac{I}{V}
1S = \frac{1A}{1V}


Resistance is defined as the ratio of Voltage over Current . Resistance is denoted as R measured in Ohm

R = \frac{V}{I}
1 = \frac{1V}{1A}


Resistance & Temperature

It's been observed that Resistance of a conductor changes with change in Temperature

R = Ro + nT For Conductor
R = Ro enT For Semi Conductor

Resistance & Electric Power Loss

Also, When conductor of resistance R conducts current . Conductor releases Heat Energy into the surrounding result in loss of Electric Power Energy directly proportional to the resistance of the conductor

P_R = I^2 R = \frac{V^2}{R}

Energy Supply , Loss and Deliver

The Energy supplies to the conductor

E_V = V I

The Energy loss as Dissipated Heat

E_R = I^2 R = \frac{V^2}{R}

The Energy Delivered without loss

E_V = E_V - E_R
E_V = VI - I^2 R = I (V - IR)
E_V = VI - \frac{V^2}{R} = V (I - \frac{V}{R})

Energy transfer Efficiency

The efficiecy of Power transmission can be calculated as the percentage of Real Power over the Supplied Power

n = \frac{E_o}{E_i}
n = \frac{E_i Cos \theta}{E_i} = Cos \theta
n = \frac{V - IR}{V}
n = \frac{I - \frac{V}{R}}{I}