1. oxygen is a very reactive element, which element in the atmosphere serves to dilute oxygen and
reduce its reactivity? a. nitrogen b. argon c. water vapor d. carbon dioxide

answer

correct answer is b(to change direct current into alternating current)

explanation

commutation

the main aim of commutation is to maintain the torque acting on armature of dc motros in the same direction.

commutator   a switch which is used to convert the direction of flow of electric current   it is connected to the armature of dc motor.

in dc motors, voltage across the armature is alternating in nature. the direction of   this current is reverses by commutator when armature of dc motors   passes through magnetic neutral axis to maintain the unidirectional. hence, commutator is used to change direct current into alternating current.

i'm not sure what you mean by "think of speed", but the way we measure it is by plugging the numbers into this formula: distance divided by time. if you are trying to find an average speed, then your formula would be: total distance divided by total time. i hope this ! : )

not too sure on this one maybe to locate objects under water, to diagnose problems, to treat medical ailments

what he said   gfgggdf