Carbon dioxide in the atmosphere is taken in by plants through the process of and given back to the atmosphere by animals through the process of  .

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

Which one of the following research methods can show cause and effect

Which is special about a dc circuit ? a. it has both series and parallel components b. it has only series or only parallel components c. charge moves in a single direction d. charge moves back and forth quickly