Question

Assertion : The value of refractive index for a given pair of media depends upon the speed of light in the two media. Reason: Refraction is due to change in the speed of light as it enters from one transparent medium to another

Answer 1

Answer:

A

Explanation:

Both are correct.

Refraction is due to change in the speed of light in various media.

Refractive index $\mu$ can be given by $\mu = \frac{c}{v}$

where c = velocity of light in vacuum and v = velocity of light in the second medium.

If the first medium is not air then c can be taken as velocity of light in the first medium.

Answer 2

Assertion:

The value of refractive index for a given pair of media depends upon the speed of light in the two media.

Reason:

Refraction is due to change in the speed of light as it enters from one transparent medium to another.

Both assertion and reason is correct and reason is the correct explaination of assertion.

• Relative refractive index of one medium w.r.t another is :

$_{1}\mu_{2} = \dfrac{ \bigg(\dfrac{v_{vacuum}}{ v_{2}} \bigg) }{ \bigg(\dfrac{v_{vacuum}}{ v_{1}} \bigg)}$

$\implies \: _{1}\mu_{2} = \dfrac{ v_{1}}{ v_{2} }$

• Hence, assertion is correct.

Also, this refraction (or deviation of path of light) occurs due to change in velocity while going from one media to another (i.e. change in wavelength too).

• Hence, reason is also true.