Question

When a low-flying aircraft passes overhead, we sometimes notice a slight shaking of the picture on our TV screen.This is because of the direct signal and reflected signal

• A. Interference
• B. Diffraction
• C. Polarisation of direct signal
• D. Both (B) and (C)

Answer 1

The correct option is A

Interference

The explanation for the correct option:

In the case of option A,

Interference:

1. When two waves having the same wavelength, frequency, and velocity move in the same direction, they can superimpose.
2. Due to the superimposition of the two waves, interference can occur.
3. Because of the interference of the waves, the resultant intensity becomes different.
4. Interference can be of two types: (i) Constructive interference, and (ii) Destructive interference.

Interference due to the low-flying aircraft:

1. When a low-flying aircraft flies over the head, it can reflect some of the TV signals back to the earth.
2. Since, the TV signal and the reflected TV signal from the airplane is having the same wavelength, frequency, and velocity, they superimpose.
3. As a result, the intensity becomes different, and a slight shaking of the picture on the TV screen can be noticed.
4. The incident can be shown by using the following diagram.

Hence, option (A) is correct.