Question

briefly describe electrical breakdown and its role in lightning

Answer 1

Electrical Breakdown is a process that occurs when an electrical insulating material,subjected to a high enough voltage ,suddenly becomes an electrical conductorand electric current flows through it . All insulating material undergo breakdown when the electric field caused by an applied voltage exceeds the material's dielectric strength.the electric field strength at which breakdown occurs is an intrinsic property of the insulating material called its dielectric strength.The voltage at which a given insulating object becomes conductive is called its breakdown voltage and depends on its size and shape.when a large enough electric field is applied to any insulating substance ,at a certain field strength the number of charge carrier in the material suddenly increase by many order of magnitude , so its resistance drops and it becomes a conductor.   Role of electric breakdown in lighting 1. During thunderstorms, the air currents move upwards while the water droplets move downwards.    2.These vigorous movement causes separation between the charges,the positive charges gets accumulated near the upper edge of the clouds and negative charges near the lower edges of the clouds.The positive charge get accumulated on the surface of the ground also.

3.when the magnitude of the accumulated charges become very large , the air which is normally a poor conductor of electricity, is no longer able to resist their flow.

4.When these negative and positive charges meet electrical discharge takes place between clouds and ground.