Speed is
a. a measure of how fast something is moving.
b. always measured in terms of a unit of distance divided by a unit of time.
c. the distance covered per unit time.
d. all of the above. e. none of the above.

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.