Question #6
Two points on a periodic wave in a medium are said to be in phase
if they
(1) have the same amplitude, only
(2) are moving in the same direction, only
(3) have the same period
(4) have the same amplitude and are moving in the same direction

The two points on a periodic wave in a medium are said to be in phase if they have the same amplitude and are moving in the same direction.

Option 4.

Explanation:

A periodic wave is termed for waves which flow in a repetition pattern in a given time scale. Periodic wave can also be termed as a transverse wave. So a transverse wave have various crests and troughs. The two successive crests and two successive troughs are said to be in phase with each other.

Thus, for a periodic wave in a medium, the in phase can be obtained in two points which have the same amplitude and are moving in the same direction.

As amplitude is a scalar quantity and so direction should be taken into consideration for making the points related to successive crests only in phase with themselves. Also this also relates the points related to successive troughs to be in phase with each other. But a crest and a trough will not be in phase with each other.

Thus, option 4, that is the two points on a periodic wave in a medium are said to be in phase if they have the same amplitude and are moving in the same direction.

multiple

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.