Hollow conductors are used in transmission line to reduce corona effect. Corona is a discharge of electricity from a conductor into the surrounding air, which causes power loss, radio and TV interference, and noise.

Explanation:

Transmission lines are used to transfer electric power from power plants to substations, where it is distributed to consumers. These lines are made of conductors, which are usually made of copper or aluminum. The size of the conductor depends on the amount of power to be transmitted and the distance it needs to travel. However, large conductors are heavy and expensive, and they also have a high corona effect.

Corona effect occurs when the electric field around the conductor exceeds a certain value, which causes the air molecules to ionize and discharge. This discharge creates a hissing sound, emits ultraviolet light, and produces ozone gas. As a result, some of the electrical energy is lost, and the transmission line becomes noisy and causes interference with radio and TV signals.

To reduce the corona effect, engineers have developed hollow conductors, which have a lower surface area per unit volume than solid conductors. This means that the electric field around the hollow conductor is lower, and the corona effect is reduced. Hollow conductors also have a lower weight per unit length than solid conductors, which makes them easier to install and maintain.

Advantages of using hollow conductors:

1. Reduced corona effect: Hollow conductors reduce the corona effect, which improves the efficiency of the transmission line and reduces the noise and interference.

2. Increased power transmission capacity: Hollow conductors can carry more power than solid conductors of the same weight and size.

3. Reduced weight: Hollow conductors weigh less than solid conductors of the same size, which makes them easier to install and maintain.

4. Improved stability: Hollow conductors have a lower sag and a higher tensile strength than solid conductors, which improves the stability of the transmission line.

Conclusion:

Hollow conductors are used in transmission lines to reduce the corona effect, increase the power transmission capacity, reduce the weight, and improve the stability. These conductors are made of aluminum or steel and have a circular or elliptical shape. Hollow conductors are an important advancement in the field of electrical engineering, which has enabled us to transmit power more efficiently and economically.

By corona effect, the ionisation of charges from sharp edges on transmission by this conductor becomes bluish colour and the charges which always flow on outersurface of conductor starts flow exponentially towards in center of cross section of conductor this causes increase in resistance of conductor by,
R=(resistivity×length)÷area of cross section(A) .

as explained above,by corona effect A decreases which inturn increases resistance.
this increase in R cause transmission efficiency to become low.
Hence,by using hollow conductors this flow of charges at center is avoided so transmission efficiency becomes good by reducing corona.

option:C