In refraction, when a wave travels from one medium to another, it
a. changes speeds.
b. stays in step.
c. always moves in the same direction.
d. travels in the opposite direction.

What causes the formation of ocean currents?

Select all the correct answers. which changes will increase the rate of reaction during combustion? decreasing the area of contact between the reactants adding more oxygen to the reaction removing heat from the reaction changing the reactants from solid form to powdered form lowering the exposure of the reactants to air

Name two kinds of practical electric pumps.