Question

The layer in the earth’s atmosphere which reflects radio waves from the earth thus, helping radio communication is:
A. Stratosphere
B. Mesosphere
C. Troposphere
D. Ionosphere

Answer 1

Hint: It is a region where air is electrically charged as the radiations from the sun knocks off electrons from it. It plays an important role in the electricity of the atmosphere and forms the magnetosphere's inner edge.

Complete step by step answer:
In the given question, we are talking about the radio waves.
These radio waves are reflected by a layer of earth’s atmosphere which we need to find out.
As we know, there are six layers of earth’s atmosphere. The layers are troposphere, stratosphere, mesosphere, thermosphere, exosphere, ionosphere.
1. Troposphere: The lowest layer of our atmosphere is the troposphere. It extends upwards to about \[10\,{\text{km}}\] ( \[6.2\] miles, or about \[33,000\] feet) above sea level, beginning at ground level.
2. Stratosphere: The stratosphere is considered the next layer up. The stratosphere rises to about \[50\,{\text{km}}\] ( \[31\] miles) above ground from the tip of the troposphere. Inside the stratosphere, the famous ozone layer is located.
3. Mesosphere: The mesosphere is situated above the stratosphere. It extends up to around \[85\,{\text{km}}\] ( \[53\] miles) above our planet in height. In the mesosphere, the bulk of meteors burn up.
4. Thermosphere: The thermosphere is considered the very unusual air layer above the mesosphere. In the thermosphere, high-energy X-rays and UV radiation from the Sun are absorbed, bringing their temperature to hundreds or even thousands of degrees.
5. Ionosphere: Solar radiation ionizes the ionosphere. It plays an important role in the energy of the atmosphere and forms the magnetosphere's inner edge. It has practical significance because it affects radio transmission to distant places on the planet, among other functions. It is an electrically conducting region which is capable of reflecting radio signals back to the earth.

From the above explanation it is clear that the ionosphere reflects radio waves from the earth thus, helping radio communication.

So, the correct answer is “Option D”.

Note:
It is important to remember that the high frequency waves travel through and escape into space through the ionosphere, while the low frequency waves reflect off the ionosphere and "skip" across the earth in turn. In the thermosphere, high-energy X-rays and UV radiation from the Sun are absorbed, bringing their temperature to hundreds or even thousands of degrees.