A layer in the Earth’s atmosphere called Ionosphere facilitates radio communication. Why? 1. The presence of ozone causes the reflection of radio waves to Earth. 2. Radio waves have a very long wavelength. Which of the statements given above is/are correct?

QUESTION

Medium

Physical Geography

Prelims 2011

A layer in the Earth’s atmosphere called Ionosphere facilitates radio communication. Why?

The presence of ozone causes the reflection of radio waves to Earth.
Radio waves have a very long wavelength.

Which of the statements given above is/are correct?

Select an option to attempt

Explanation

Statement 1 is incorrect: The reflection of radio waves is due to the presence of ions and free electrons in the Ionosphere (Thermosphere), not ozone. The Ozone layer is located in the Stratosphere and absorbs UV rays; it does not reflect radio waves.

Statement 2 is incorrect: While radio waves have longer wavelengths than light, the reason they are reflected is due to the refractive index of the ionized plasma. The reflection depends on the Critical Frequency of the ionospheric layer. If a wave's frequency is higher than the critical frequency (even if it has a "long" wavelength relative to light), it will pass through into space. Thus, "having a very long wavelength" is not the scientific cause of the phenomenon.

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