Saturday, 21 January 2017

DC NETWORK THEOREM - ELECTRICAL ENGINEERING BASIC



Current: “Rate of flow of electric charge.”
time
Charge
I = Coulombs/Sec or Ampere
Note:-
1. Direction of current is same as the direction of motion of +Ve charge or opposite to the direction of
motion of –Ve charge.

Voltage:Energy required in transferring a charge of one coulomb from one point to
another point.”
Charge(Q)
Energy(W)
V = Joule/Coulomb or Volts

EMF (Electromotive force): “The EMF of a voltage source is the energy imparted by
the source to each coulomb of the charge passing through it.”
Charge(Q)
Energy(W)
E = Joule/Coulomb or Volts

Potential Difference: “The pd between two points is the energy required in transferring a
charge of coulomb from one point to another point.”
Charge(Q)
Energy(W)
pd = Joule/Coulomb or Volts

Voltage drop: “The voltage drop between two points is the decrease in energy required
in transferring a charge of coulomb from one point to another point.”
Charge(Q)
Energy(W)
Voltage drop = Joule/Coulomb or Volts

Resistance: “Electric resistance is the property of material which offers opposition to the
flow of current and dissipates energy.”
a
l
R = ñ Ohm or _ (Law of resistance)
Where l = Length of the wire
a = cross sectional area of the wire
ñ = Resistivity or Specific Resistance of the material
Note:-

1. Resistance also depends on temperature.

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