When the ignition is first turned on a click noise is heard from under the hood of a vehicle equipped with etc. technician a says that this is the normal operation of the etc self-test. technician b says that the tac motor should not move unless the engine is running. which technician is correct?

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.