Kennelly-Heaviside' layer in Ionosphere is :

Question

Accepted Answer

The Kennelly-Heaviside layer, also known as the E layer, is a region of the Earth's ionosphere. It is named after Arthur E. Kennelly and Oliver Heaviside, who independently proposed its existence in the early 20th century. The E layer is located approximately 90 to 150 kilometers above the Earth's surface and plays a crucial role in radio wave propagation.

1. **Explanation for Option 2 (E Layer):**
   - The E layer is part of the ionosphere, which is a region of the Earth's upper atmosphere that is ionized by solar and cosmic radiation. This ionization allows the E layer to reflect medium-frequency radio waves, making long-distance radio communication possible by bouncing signals back to Earth.
   - The E layer is particularly important for AM radio transmissions during the daytime. It reflects radio waves back to the Earth's surface, allowing them to travel beyond the horizon.
   - The layer's ionization levels can vary with solar activity, time of day, and season, affecting its ability to reflect radio waves.

2. **Explanation for why other options are incorrect:**

- **Option 1 (D Layer):**
     - The D layer is the lowest part of the ionosphere, located about 60 to 90 kilometers above the Earth. It is primarily responsible for absorbing high-frequency radio waves rather than reflecting them. This absorption is more pronounced during the daytime due to increased ionization from solar radiation. Therefore, it does not serve the same reflective function as the E layer.

- **Option 3 (F Layer):**
     - The F layer is higher up in the ionosphere, located above the E layer, and is divided into F1 and F2 layers. While the F layer is crucial for reflecting high-frequency radio waves, especially at night, it is not the Kennelly-Heaviside layer. The F layer's primary role is in long-distance communication and is more effective at higher frequencies than the E layer.

- **Option 4 (G Layer):**
     - There is no recognized G layer in the ionosphere. The ionosphere is typically divided into the D, E, and F layers. Therefore, Option 4 is incorrect as it does not correspond to any known layer within the ionosphere.

In conclusion, the Kennelly-Heaviside layer is correctly identified as the E layer, as it is responsible for reflecting medium-frequency radio waves and facilitating radio communication over long distances. The other options do not accurately describe the Kennelly-Heaviside layer's characteristics or functions.