Answer: Electric current
Explanation :
The direction of the magnetic field produced by an electric current will change when the direction of the electric current changes.
For example :
If a current is flowing in a straight length of wire, the magnetic field is described by a concentric circle (using right-hand rule).
Let the field lines are in the clockwise direction and when the direction of current is reversed then the direction of the magnetic field is in anticlockwise direction.
I think it’s mechanical waves..
-Glomar Challenger studies about the "age of rocks in various places in the ocean" in 1968.
(Glomar Challenger was a "deep sea research vessel" for marine geology and oceanography studies)
hope this helps!! :))
Higher pitched sounds produce waves which are closer together than for lower pitched sounds. A smaller triangle or cymbal will make a relatively higher pitch note
-- The theory of gravity gives a good explanation for things
that we see happening.
-- The theory of gravity predicts things that turn out to be true
when we test them.
-- Nobody has come up with a different theory that explains things better
and makes more accurate predictions that the theory of gravity does.
-- The theory of gravity can't be proved.