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A parallel beamof white light is made of...

A parallel beamof white light is made of fall on an equiconvex lens made of glass.When the screen is kept at a distance`10cm`,a spot of violet light is observed at center and outer ring of red colour of radius`1mm`.Teh radius of curvature of lens is `6cm`each and aperture diameter is `2cm`Then:

A

Refractive index of the glass of red light is`1.27`

B

Refractive index of the glass for red light is`1.3`

C

Dispersive power of lens is nearly`0.1`

D

Dispersive power of lens is nearly`0.2`

Text Solution

Verified by Experts

The correct Answer is:
A,C

(B) `(1)/(f_(v))=(mu_(v)-1)((1)/(R_(1))-(1)/(R_(2))) rArr (1)/(10)=(mu_(v)-1)((1)/(6)-(1)/(-6))`
`(1)/(10)=(mu_(v)-1)(1)/(3) rArr mu_(v)-1=(3)/(10) mu_(v)=1.3`
L.C.A=`omegaf`
`dF=omegaf`
`omega=(df)/(f) rArr omega=(f_(R)-f_(V))/(f_(V))`
`omega=(0.1)/(1)`
`omega=0.1`
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