Question

Top of the stratosphere has an electric field $E$(in units of $v/m$) nearly equal to
(A) $0$
(B) $10$
(C) $100$
(D) $1000$

Answer 1

Hint: Atmospheric electricity is the cause of electric-field in the atmosphere. Atmospheric electricity is the study of electrical charges in the Earth's atmosphere (or that of any other planet). The movement of charge between the Earth's surface, the atmosphere, and the ionosphere is known as the global atmospheric electrical circuit, this is the reason for lighting to take place. We solve this question by seeing how the average electric field varies along the atmosphere.

Complete step has step answer: Thunderstorms or lighting act as a giant battery in the atmosphere, charging up the atmosphere to up to $400,000volts$ with respect to the surface. This creates an electric field throughout the atmosphere. This electric field decreases with increase in altitude.
At the surface of earth, the average electric field is equal to $100v/m$ as we go up towards the atmosphere it keeps decreasing. At the top of the stratosphere the electric field is equal to $10v/m$.

Hence option (B) $10v/m$ is the correct answer

Additional information: Similar phenomenon is observed in other planets as well. Studies have discovered planets that have thunderstorms all the time. This is because of the difference in electric field between the atmosphere and the surface of earth being high all the time.

Note: Atmospheric electricity involves both thunderstorms (lightning) which create lightning bolts to rapidly exchange huge amounts of atmospheric charge stored in clouds during storms, and also the continual electrification of the air due to ionization from cosmic-rays. Which ensures that the atmosphere is never quite neutral in charge. This difference in charge causes lighting in the form of static electricity to balance the charge.