Correct Answer - Option 2 : point-point electrode arrangement
Concept:
- A gas in its normal state is almost a perfect insulator, however, when a high voltage is applied between the two electrode immersed in a gaseous medium. The gas becomes a conductor and an electrical breakdown occurs.
- The processes that are primarily responsible for the breakdown of gas are ionized by collision, photo ionization and the secondary ionization processes.
- The process of liberating an electron from a gas molecule with the simultaneous production of a positive ion is called ionization.
- If the electric field is uniform, a gradual increase in voltage across a gap produces a breakdown in voltage across the gap on the other hand, if the field is non-uniform an increase in voltage will first cause a discharge in the gas to appear at points with highest electric field intensity, namely at sharp points or where the electrodes are curved or on transmission lines.
Explanation:
The set of electrodes are as follows.
Sphere-Sphere electrodes: The maximum electric field decreases with the increase in the gap distance. In the beginning there is sharp drop in the maximum electric field but it gradually saturates with increase in the gap distance.
Point to Point electrodes: The electric field distribution in the rod plate gap is non uniform in nature. Most severe non-uniform field is developed in this arrangement.
Plate-rod electrodes: The electric field is maximum at the tip of the rod and it decreases along the axis joining the rods and again increases. The electric field between the rods is much more inhomogeneous than in the sphere-sphere arrangement.
