Two symmetric double convex lenses A and B have the same focal length but the radii of curvature differ so that RA=0.9 RB . If μA=1.63, then μB is

Question

Two symmetric double convex lenses A and B have the same focal length but the radii of curvature differ so that RA=0.9 RB . If μA=1.63, then μB is (A) 1.1 (B) 1.5 (C) 1.6 (D) 1.7

Tardigrade Admin · Accepted Answer

(1/fA)=(μA-1)[(1/RA)-(1/-RA)]=((μA-1) 2/RA) Similarly, (1/fB)=((μB-1) 2/RB) Given that fA=fB ⇒ ((μA-1) 2/RA)=((μB-1) 2/RB) ⇒ (μB-1)=((μA-1) ⋅ RB/RA)=((1.63-1) RB/(0.9 RB))=0.7 or μB=1.7.

Q. Two symmetric double convex lenses A and B have the same focal length but the radii of curvature differ so that RA​=0.9RB​. If μA​=1.63, then μB​ is

1.1

1.5

1.6

1.7

fA​1​=(μA​−1)[RA​1​−−RA​1​]=RA​(μA​−1)2​ Similarly, fB​1​=RB​(μB​−1)2​ Given that fA​=fB​⇒RA​(μA​−1)2​=RB​(μB​−1)2​ ⇒(μB​−1)=RA​(μA​−1)⋅RB​​=(0.9RB​)(1.63−1)RB​​=0.7 or μB​=1.7.

Q. Two symmetric double convex lenses $A$ and $B$ have the same focal length but the radii of curvature differ so that $R_{A} = 0.9 R_{B} .$ If $μ_{A} = 1.63,$ then $μ_{B}$ is