When we talk about a material, it has several physical properties, such as strength, density, thermal properties, and electrical properties. Of these, electrical properties are those properties that describe how and to what extent a material can conduct electricity.
Not every material conducts electricity the same way. Some materials are good conductors of electricity, such as copper and aluminum, while others are not at all conductors, such as rubber, plastic, or wood. In between, there are some materials called semiconductors, such as silicon and germanium.
To understand the behavior of all these, it is important for us to know their electrical properties.
What are Electrical Properties?
Electrical properties describe the ability of a substance to conduct, store, or resist electricity. This property depends on the movement and freedom of electrons within the substance.
In simple words:
“How electricity flows through a substance, how easily it flows, or how much it resists – all this is revealed by electrical properties.”
Types of Electrical Properties
There are many types of electrical properties, depending on the material’s ability to conduct, resist, or store electricity.
Below we understand all the major Electrical Properties in detail,
1. Electrical Conductivity
It tells us how easily a substance can conduct electricity. A substance with high conductivity is called a good conductor.
- Materials with high conductivity: Copper, Silver, Aluminum
- Materials with low conductivity: Wood, Rubber, Glass
The formula for Electrical Conductivity (σ) is:
σ = 1 / ρ
Where,
ρ = Resistivity
Unit: Siemens per meter (S/m)
2. Electrical Resistivity
It describes a material’s ability to resist the flow of electricity. The higher the resistivity, the less electricity will flow through it.
Formula:
ρ=R * A / L
Where,
- R = Resistance (in ohms)
- A = Cross-sectional area (in m²)
- L = Length (in meters)
Example:
- Rubber has a very high resistivity – electricity does not flow.
- Copper has a very low resistivity – electricity flows easily.
3. Electrical Conductance
It is a measure of a material’s ability to conduct electricity. It is the opposite of resistivity.
Formula:
G = 1 / R
Unit: Siemens (S)
4. Dielectric Strength
It tells us how many volts of electric stress a material can withstand without breaking down. This property is most important in insulating materials.
Examples:
- Air – approximately 3 × 10⁶ V/m
- Mica – approximately 100 × 10⁶ V/m
The higher the dielectric strength, the better the insulator the substance is.
5. Permittivity
It tells us how much electrical energy a material can store in an electric field. Permittivity is directly related to capacitance.
Formula:
C = ε * A / d
Where,
- C = Capacitance
- ε = Permittivity
- A = Area
- d = Distance between the plates
6. Dielectric Constant (K)
It tells us how much electrical energy a substance can store compared to a vacuum.
Formula:
K = ε / ε₀
Where ε₀ = Vacuum permittivity
Example:
- Vacuum = 1
- Water = 80
- Glass = 5–10
7. Electric Susceptibility
It describes how polarized a substance is under the influence of an electric field. Polarization is when the positive and negative charges within a substance are slightly separated.
8. Dielectric Loss
When an alternating electric field is applied to an insulator, some energy is lost in the form of heat, this is called dielectric loss.
This is especially important in capacitors and high voltage devices.
9. Electrical Polarization
When an electric field is applied to a substance, the atoms or ions within it shift slightly. This creates a “microscopic dipole” inside, a process called electrical polarization.
Factors Affecting Electrical Properties
1. Temperature
- Conductivity decreases with increasing temperature.
- The opposite is true for semiconductors; conductivity increases with increasing temperature.
2. Impurities
- Slight impurities can change the conductivity of a substance.
- The same principle applies to semiconductors (P-type, N-type).
3. Crystal Structure
- The arrangement of atoms affects the flow of electricity.
4. Pressure and Stress
- These properties are directly reflected in piezoelectric materials.
Types of Materials Based on Electrical Properties
| Category | Description | Example |
|---|---|---|
| Conductors | conducts electricity easily | Copper, Silver, Aluminum |
| Insulators | Do not conduct electricity | Rubber, Plastic, Mica |
| Semiconductors | have intermediate properties | Silicon, Germanium |
| Superconductors | Zero resistivity | Mercury, Niobium |
Importance of Electrical Properties
Understanding electrical properties is very important for electrical engineering, electronics, physics and material science.
- It helps develop new conductors and semiconductors.
- Energy efficiency in electrical devices can be increased.
- Better insulation materials can be created.
- Superconductors can enable new technologies (Maglev Trains, MRI machines).
Conclusion
Electrical properties are some of the most important physical properties of a substance. They describe how electricity travels through a substance, where it stops, and how much it affects it.
The design of any machine, wire, transistor, or electronic device depends on these properties. Therefore, understanding electrical properties is essential for every engineer, scientist, and student.