The frequency of the wave has not changed.
In fact, the frequency of a wave is given by:
where v is the wave's speed and 
is the wavelength.
Applying the formula:
- In air, the frequency of the wave is:
- underwater, the frequency of the wave is:
So, the frequency has not changed.
At the equator, the North Celestial and South Celestial Poles would lie on the horizon where the meridian intersects the horizon. Polaris is called the "North Star." ... Polaris is special because the Earth's North Pole points almost exactly towards it.
The frequency of the radio station is
For radio waves (which are electromagnetic waves), the relationship between frequency f and wavelength
is
where c is the speed of light. Substituting the frequency of the radio station, we find the wavelength:
A piece of blue paper appears blue because the paper absorbs all colors of light except blue. <em> (b)</em>
So any light that bounces off of the paper and enters your eye must be blue light !
