Electrical resistance and conductance

Electrical Resistance and Conductance are fundamental concepts in the field of Electrical Engineering and Physics, playing a crucial role in understanding how electric currents flow through different materials. These concepts are not only pivotal in technical fields but also have practical applications in various aspects of modern life, including medical technologies.

Electrical Resistance

Electrical resistance is a measure of the opposition to the flow of electric current through a conductor. It is determined by the material's properties, its length, and cross-sectional area. The unit of resistance is the ohm (Ω). According to Ohm's Law, resistance (R) is calculated as the ratio of voltage (V) across the conductor to the current (I) flowing through it, expressed as R = V/I.

Materials with high resistance require more energy to allow the flow of electrical current and are called insulators, such as rubber and glass. Conversely, conductors, like metals, have low resistance and allow easy flow of electric current.

Electrical Conductance

Electrical conductance is the reciprocal of electrical resistance and measures a material's ability to conduct an electric current. It is represented by the symbol G and its unit is the siemens (S). Conductance is calculated as G = 1/R = I/V, where I is the current flowing through the material and V is the voltage across it.

Factors Affecting Resistance and Conductance

Several factors influence the resistance and conductance of a material:

• Material: The type of material is a significant factor. Conductors have low resistance and high conductance, while insulators have high resistance and low conductance.
• Temperature: For most materials, resistance increases with temperature. In superconductors, resistance drops to zero below a certain temperature.
• Geometry: The length and cross-sectional area of a material affect its resistance and conductance. Longer wires have higher resistance, and thicker wires have lower resistance.

Applications in Medicine

In the medical field, the principles of electrical resistance and conductance are applied in various diagnostic and therapeutic technologies. For example, Electrocardiography (ECG) and Electroencephalography (EEG) rely on the electrical conductance properties of the human body to monitor heart and brain activity, respectively. Additionally, electrical resistance is a principle behind the operation of medical devices such as Defibrillators and Pacemakers, which regulate heart rhythm.

Conclusion

Understanding electrical resistance and conductance is essential for the development and application of electrical and electronic devices, including those used in medical technology. These concepts provide a foundation for designing circuits and systems that improve our daily lives and health.