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Do object reflect radio waves just like light waves? I don't know much about their use but can anyone explain how we use this reflection?

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    $\begingroup$ This is far too broad as it stands, and comes dangerously close to insufficient effort. Start with the Wikipedia article and Google as appropriate if you want more technical information. $\endgroup$ May 19, 2014 at 5:54

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When the radio waves from the transmitting antenna reach the receiving antenna after reflection in the ionosphere, the wave propagation is called sky wave propagation.

The upper part of the atmosphere absorbs large amounts of radiant energy from the sun. The intensive heating of the atmosphere during day time causes ionisation, resulting in free electrons, positive ions and negative ions. However, due to different chemical compositions and physical properties of the atmosphere at different heights, the ionisation in the atmosphere is not uniform. The electron concentration in a layer extending from 90 km to 140 km from the surface of earth, called Kennelly Heaviside layer (or E-layer) and then in a layer extending from 250 km to 400 km, called Appletion layer (or F-layer). Most of the reflection takes place in these two layers.

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The electromagnetic waves of frequency up to 30 MHz get reflected by the ionosphere. However, when the frequency of electromagnetic waves is above 40 MHz, they are no longer reflected by the ionosphere but undergo refraction.

The angle above which the radio waves are no longer reflected by the ionosphere is called critical angle of radiation. Its value depends on the density of ionisation and on the frequency of the radio waves.

So, considering the above example, whether the objects reflects radio waves or not depends on many factors, like absorbing power, critical angle of radiation, frequency, etc. For your question, radio waves can be reflected by objects, but not always.

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Yes, and you can use it for science.

Reflecting them into a receiver is an important step in making a radio telescope.

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