B. number of oscillations in a given period of time.
Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field. ... They are hence known as 'electromagnetic' waves. The electric field and magnetic field of an electromagnetic wave are perpendicular (at right angles) to each other.
Hope this helps.
:)
Answer:

Explanation:
We are given that
Frequency,f=800KHz=

Distance,d=4.5 km=
1 km=1000 m
Electric field,E=0.63V/m
We have to find the magnetic field amplitude of the signal at that point.

We know that



To find the acceleration, we would need to use the equation acceleration= final velocity- initial velocity/elapsed time. Since the final velocity is 35 and the initial velocity is 65, we can subtract 65 from 35 first, which gives us -30. Then if we divide that by the elapsed time, which is 10, we get -3. Your acceleration is -3 meters per second.
Hope this helps! :D