NEETPhysicsElectromagnetic Waves
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The speed of light in a transparent material medium is always less than its speed in vacuum. Reason (R): For any transparent material medium, the product of its relative permittivity and relative permeability is always less than 1. In the light of the above statements, choose the most appropriate a
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A).
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A).
- C(A) is true but (R) is false.
- D(A) is false but (R) is true.
Correct answer
C. (A) is true but (R) is false.
Step-by-step solution
The speed of light in a medium is given by v = c _r _r , where c is the speed of light in vacuum, _r is the relative permeability, and _r is the relative permittivity of the medium. For any transparent material medium, the relative permittivity (dielectric constant) _r > 1 and relative permeability _r 1 (for non-magnetic materials) or slightly different, making their product _r _r > 1 . Since the denominator is greater than 1, the speed of light in the medium v is always less than c . Thus, the Assertion is true. T