Electric Current and Ohm’s Law

Electric current and Ohm's law is very much essential parts of knowing as an electrical engineer.  I'll provide brief explanations for each term:

Electron Drift Velocity:

The average velocity of electrons in a conductor in response to an electric field.

Charge Velocity and Velocity of Field Propagation:

Charge velocity refers to the movement of electric charge, typically electrons. The velocity of field propagation is the speed at which changes in the electric field travel through a medium.

The Idea of Electric Potential:

Electric potential, or voltage, is the electric potential energy per unit charge at a point in space. It represents the work done by an external force in bringing a charge from infinity to that point.

Resistance:

The opposition that a material offers to the flow of electric current.

Unit of Resistance:

The unit of resistance is the ohm (Ω).

Law of Resistance:

Ohm's Law states that the current passing through a conductor between two points is directly proportional to the voltage across the two points, given a constant temperature.

Units of Resistivity:

Resistivity is measured in ohm-meter (Ω·m).

Conductance and Conductivity:

Conductance is the reciprocal of resistance. Conductivity is the measure of a material's ability to conduct electric current and is the inverse of resistivity.

Effect of Temperature on Resistance:

Generally, the resistance of conductors increases with an increase in temperature.

Temperature Coefficient of Resistance:

A measure of how much a material's resistance changes per degree Celsius change in temperature.

Ohm’s Law:

States the relationship between voltage, current, and resistance: 

V=I×R.

Resistance in Series:

The total resistance in a series circuit is the sum of individual resistances.

Voltage Divider Rule:

A rule used to find the voltage across a specific resistor in a series circuit.

Resistance in Parallel:

The reciprocal of the total resistance in a parallel circuit is equal to the sum of the reciprocals of the individual resistances.

Types of Resistors:

Resistors can be fixed or variable. They come in various forms such as carbon composition, film, wire-wound, etc.

Nonlinear Resistors:

Resistors whose resistance changes with voltage or current, like varistors.

Varistor:

A variable resistor whose resistance decreases with increasing voltage.

Short and Open Circuits:

A short circuit occurs when there is a low-resistance connection between two points, bypassing the normal load. An open circuit occurs when there is a break in the circuit,

‘Shorts’ in a Series Circuit:

A short circuit in a series circuit would interrupt the flow of current.

‘Opens’ in Series Circuit:

An open circuit in a series circuit would also interrupt the flow of current.

‘Open’s in a Parallel Circuit:

An open circuit in a parallel circuit would not affect the other branches.

‘Shorts’ in Parallel Circuits:

A short circuit in a parallel circuit would create a low-resistance path for current.

Division of Current in Parallel Circuits:

The total current entering a parallel circuit is divided among the different branches.

Equivalent Resistance:

The single resistance value can replace a set of resistors in a circuit without changing the overall current or voltage.

Duality Between Series and Parallel Circuits:

There is a mathematical relationship between series and parallel circuits called electrical duality.

Relative Potential:

The electric potential at a point relative to some reference point.

Voltage Divider Circuits:

Circuits where a series of resistors divide the voltage in a predictable manner.

These concepts collectively form the foundation of understanding electrical circuits and their behavior.