AIIMS2018Physics-Electromagnetic Waves

AIIMS 2018 Physics Antenna Theory MCQ Question

Type: MCQ-conceptual-Easy-Class 12

The fundamental radio antenna is a metal rod which has a length equal to

A

λ\lambda in free space at the frequency of operation.

B

λ2\frac{\lambda}{2} in free space at the frequency of operation.

C

λ4\frac{\lambda}{4} in free space at the frequency of operation.

D

3λ4\frac{3\lambda}{4} in free space at the frequency of operation.

Correct Answer

Option C

Detailed Explanation

A straight conductor of length L = λ/4, when held vertically with its lower end touching the ground, acts as a quarter-wave monopole antenna. This configuration allows it to efficiently radiate electromagnetic waves, as the ground acts as a reflecting surface, effectively doubling the antenna's length for radiation purposes. Other options are not applicable or relevant to the characteristics of a quarter-wave antenna, which is specifically designed for optimal performance at its resonant frequency. Understanding the principles of antenna design, including the role of ground planes, is crucial for effective communication systems.

Found an issue with this question?