At a particular location, the electric field points due north. (a) In what direction(s) will the rate of change of potential be greatest? (b) In what direction(s) will the rate of change of potential be least?

a) The biggest change is in the North direction towards the south

b)   the lowest exchange rate is in the esast -west where the change is zero

Explanation:

The field and the electric potential are related

          ΔV = - E ds

In the direction that the field increases the potential decreases

If the electro field points to the north, the potential must have an opposite behavior, or it must decrease towards the North.

Let's apply these deductions to the exercise.

a) The potential is greater towards the SOUTH

Therefore the biggest change is in the North direction towards the south

b) the lowest exchange rate is in the east- west where the change is zero

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.