Electromagnetic Wave Propagation

1. A longitudinal wave involves oscillations of particles of a medium in the direction of wave propagation.
2. During the wave's travel, the medium undergoes alternating compression and rarefaction. In the compression region, particles are closely packed together, while in the rarefaction region, they are farther apart.
3. Since the density is defined as mass per unit volume, and volume changes in compression and rarefaction regions, the density of the medium will also vary.
4. Therefore, the correct answer is: .

Using the formula for the radio horizon, we can calculate the distance to the horizon based on the height of the antenna and Earth's radius.

The general form of a plane electromagnetic wave is:
Given: rad/s and wave is in vacuum
In vacuum, wave speed
m/s, so: m

Line-of-sight (LOS) communication requires that the transmitter and receiver be in direct view of each other without any obstacles in between.
Space waves, which include microwave and UHF radio waves, travel in straight lines and are suitable for LOS communication such as TV transmission, satellite links, and mobile phones.
Sky waves reflect off the ionosphere, and ground waves follow the curvature of the Earth, both of which are not line-of-sight.