From which layer of the atmosphere do radio waves come back?

Correct option is C

The ionosphere is the layer of the atmosphere responsible for the reflection of radio waves back to Earth. It is a sub-layer of the thermosphere and extends 50 to 400 miles (80–640 km) above Earth's surface. This layer contains a high concentration of ionized particles (electrically charged atoms and molecules), which makes it capable of reflecting and refracting radio waves.
· When radio waves are transmitted from Earth, they travel towards the ionosphere.
· The charged particles in the ionosphere reflect certain frequencies of radio waves back to the Earth's surface.
· This phenomenon allows long-distance radio communication, particularly for AM and shortwave radio transmissions.
· The ionosphere plays a crucial role in atmospheric electricity and also forms the inner edge of the magnetosphere, which protects Earth from solar radiation.
Thus, the correct answer is (c) Ionosphere.
Information Booster:
· The ionosphere supports long-distance radio communication by reflecting signals back to Earth.
· It contains electrically charged particles (ions) that interact with radio waves.
· The ionosphere is influenced by solar activity, which can enhance or disrupt radio wave propagation.
· It is part of the thermosphere, which extends beyond the mesosphere.
· The Auroras (Northern and Southern Lights) occur in this layer due to interactions between charged solar particles and Earth's magnetic field.
· The ionosphere is divided into three sub-layers: D, E, and F layers, each affecting different frequencies of radio waves.
Additional Knowledge:
(A) Structure of the Atmosphere:
The Earth's atmosphere is divided into five primary layers, each with distinct characteristics:
1. Troposphere (0-13 km):
· Closest to Earth’s surface, where weather phenomena occur.
· Contains about 75% of the total atmospheric mass.
2. Stratosphere (13-50 km):
· Contains the ozone layer, which absorbs harmful UV radiation.
· Jet planes fly in this region due to stable air conditions.
3. Mesosphere (50-80 km):
· Meteorites burn up in this layer due to friction.
· Coldest layer of the atmosphere.
4. Thermosphere (80-640 km):
· Contains the ionosphere, which reflects radio waves.
· Space shuttles and the International Space Station (ISS) orbit in this layer.
5. Exosphere (640 km and beyond):
· Outermost layer, gradually merging into space.
· Contains light gases like hydrogen and helium.
(B) Role of the Ionosphere in Communication:
· The ionosphere is critical for global radio communication.
· Shortwave radio signals are bounced back to Earth, allowing them to travel long distances.
· Satellite-based communication (GPS, TV broadcasting) must account for ionospheric interference.
(C) Effects of Solar Activity on the Ionosphere:
· Solar flares and geomagnetic storms can disrupt ionospheric conditions, affecting radio transmissions.
· During periods of high solar activity, the ionosphere becomes more ionized, improving radio wave reflection.
· The Auroras are formed due to interactions between solar particles and ionospheric ions.