Which parameter of a transmission line describes its ability to store electrical energy in the form of an electric field__ A- Resistance B- Capacitance C- Inductance D- Conductance
The correct answer and explanation is:
The correct answer is B – Capacitance.
In a transmission line, the ability to store electrical energy in the form of an electric field is described by the capacitance of the line. A transmission line typically consists of two conductors, with an insulating material (dielectric) between them. When an electrical voltage is applied to the conductors, an electric field is established between them. This electric field stores energy in the form of potential energy. The capacitance is the parameter that quantifies this ability.
Capacitance in a transmission line depends on several factors, including the physical dimensions of the conductors, the distance between them, and the properties of the dielectric material separating them. The unit of capacitance is the farad (F), and it is calculated as: C=ϵAdC = \frac{\epsilon A}{d}
Where:
- CC is the capacitance,
- ϵ\epsilon is the permittivity of the dielectric material,
- AA is the cross-sectional area of the conductors,
- dd is the distance between the conductors.
A higher capacitance means the transmission line can store more energy in the form of an electric field for a given voltage. Capacitance plays an essential role in determining the characteristic impedance of the transmission line, which is important for signal integrity in high-frequency applications.
The other parameters are:
- A – Resistance: This parameter describes the loss of energy due to the resistance of the conductors but does not store energy in an electric field.
- C – Inductance: Inductance is the ability to store energy in a magnetic field, not an electric field.
- D – Conductance: This describes the ease with which a transmission line allows current to flow and is related to resistive losses, not energy storage in an electric field.
In summary, capacitance is the key parameter that governs a transmission line’s ability to store energy in an electric field.