question_answer

This question has Statement-1 and Statement-2. Of four choices given after the Statements, choose the one that best describes the two Statements.

Statement 1: Short wave transmission is achieved due to the total internal reflection of the e-m wave from an appropriate height in the ionosphere.

Statement 2: Refractive index of a plasma is independent of the frequency of e-m waves.

[JEE ONLINE 22-04-2013]

A) Statement 1 is true, Statement 2 is false

B)             Statement 1 is false, Statement 2 is true

C)             Statement 1 is true, Statement 2 is true but Statement 2 is not the correct explanation of Statement 1

D)             Statement 1 is true, Statement 2 is true but Statement 2 is the correct explanation of Statement 1

Correct Answer: A

Solution :

[a] Effective refractive index of the ionosphere

where f is the frequency of cm waves