Contact

For Enquiry

10:00 AM to 7:00 PM IST all days.

Business Inquiry (West / East / South)

OR

or

Thanks, You will receive a call shortly.
Customer Support

You are very important to us

022-62211530

Mon to Sat - 10 AM to 7 PM

# As we know refrective index for mean colour yellow is ( μv + μr) /2Why can't we apply this formula directly here, ( answer is different in both cases)Please Explain..!

Asked by jhajuhi19 14th November 2019, 10:44 AM
( μv + μr )/2  is mean refractive index for prism and it is approximately taken as μy .

( μ is refractive index , subscripts v, r and y stands for violet, red and yellow colour respectively )

Dispersive power ω of prism is defined as,  ω = ( δv - δr ) / δ  ...............(1)

where δv is angular deviation for violet colour and δr is angular deviation for red colour.

δ is mean deviation, that is considered as deviation of yellow colour

since deviation δ = (μ-1)A , where μ is the refractive index of material of prism and A is angle of prism,

Eqn.(1) is written using the respective refractive indices as , ω = ( μv - μr )/ ( μy - 1)  .............(2)

In eqn.(2) mean deviation is considered as deviation due to yellow colour.

while solving problems related to dispersion in glass prism, if μy is not given, we take arithmetic mean of μv and μr for
mean refractive index and find the dispersive power.

For given dispersive power, if we need to find μy using the given values of μv and μr , then we should use the equation (2)
Answered by Expert 14th November 2019, 5:00 PM
• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10

You have rated this answer /10

Tags: dispersion