Diode Current Equation
Single Phase Transformer
Electrical Engineering Materials
Classification of Engineering Materials
Classification of Electrical Engineering Materials
Physical Properties of Materials
Mechanical Properties of Engineering Materials
Chemical Properties of Materials
Electrical Properties of Engineering Materials
Magnetic Properties of Engineering Materials
Selection of Material for Engineering Application
Bases of existence of properties in materials
Low Resistivity or High Conductivity of Conducting Material
High Resistivity or Low Conductivity Conducting Material
Factors Effecting the Resistivity of Electrical Materials
Materials used for Heating Elements
Materials used for Precious Works
Materials Used for Transmission Line Conductor
Electrical Stranded Conductors
Materials used for Rheostats
Materials for Lamp Filaments
Temperature Coefficient of Resistance
Classification of Electrical Conducting Material
Applications of Carbon Materials in Electrical Engineering
Selection of Materials Used for Electrical Contacts
Mechanism of Polarization
Dielectric Material as an Electric Field Medium
Electric Arc Furnace
Thermal Conductivity of Metals
Free Electron Theory of Metals
What is an Atom?
Atomic Energy Levels
Electron Configuration of Atom
Thomson Plum Pudding Model (1911)
Rutherford Atomic Model
Bohrs Atomic Model
Energy Bands in Crystals
Fermi Dirac Distribution Function
How a Conductor Conducts Current?The substance of the electrical conductor atom must have no energy gap between its valence band and conduction band. The outer electrons in the valence band are loosely attached to the atom. When an electron gets excited due to electromotive force or thermal effect, it moves from its valence band to conduction band. Conduction band is the band where this electron gets its freedom to move anywhere in the conductor. The conductor is formed of atoms. Thus as a whole, the conduction band is in abundance of electrons. In other word, it can be said that the metallic bonds are present in the conductors. These metallic bonds are based on structure of positive metal ions. These structures are surrounded by electron cloud.
When a potential difference occurs in the conductor across two points, the electrons get sufficient energy to flow from lower potency to higher potency in this conduction band against a small resistance offered by this conductor material. Electricity or current flows in the opposite direction of the flow of the electrons.
How an Electron Flows through a Conductor?Electrons do not move or flow in a straight line. In a conductor, the electrons are in to and fro motion or random velocity i.e. is called Drift Velocity (Vd) or average velocity. Due to this Drift Velocity, the electrons get collisions every moment with atoms or another electron in the conduction band of the conductor. Drift velocity is quite small, as there are so many free electrons. We can estimate the density of free electrons in a conductor, thus we can calculate the drift velocity for a given current. The larger the density, the lower the velocity required for a given current. In the Conductor, flow of the electrons is against the Electric Field (E).
Properties of ConductorThe main properties that should be with a conductor are as follows:
- A conductor always allows free movement of electrons or ions.
- The electric field inside a conductor must be zero to permit the electrons or ions to move through the conductor.
- Charge density inside a conductor is zero i.e. the positive and negative charges cancel inside a conductor.
- As no charge inside the conductor, only free charges can exist only on the surface of a conductor.
- The electric field is perpendicular to the surface of that conductor.
Type of the ConductorsGenerally conductors can be classified based on Ohmic Response. They are
Ohmic ConductorsThis type of conductors always follow Ohm’s Law (V ∝ I) V vs. I graph gives a straight line always. Example Aluminum, Silver, Copper etc.
Non Ohmic ConductorsThis type of conductors never follow the Ohm’s Law (V ∝ I) V vs. I graph does not give a straight line i.e. non linear graph. Example LDR (Light Dependant Resistor), Diode, Filament of Bulb, Thermistor etc. The examples of conductors are given below
- Metallic Conductor: Silver, Copper, Aluminum, Gold etc.
- Non Metallic Conductor: Graphite
- Alloy Conductor: Brass, Bronze etc.
- Metallic Conductor: Mercury
- Non Metallic Conductor: Saline Water, Acid Solution etc.
- Copper Conductor is the most common material used for electrical wiring.
- Gold Conductor is used for high-quality surface-to-surface contacts.
- Silver is the best conductor in the Conductors list.
- Impure Water is listed in Conductor List but it has less conductivity.