Question
Physics Question on Spherical Mirrors
A spherical surface of radius of curvature R, separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O and PO = O The distance PO is equal to
A
5 R
B
3 R
C
2 R
D
1.5 R
Answer
5 R
Explanation
Solution
The correct option is(A): 5 R.
Let us say PO = OQ = X
Applyingvμ2−uμ1=Rμ1−μ2
Substituting the values with sign
+X1.5−−X1.0=+R1.5−1.0
(Distances are measured from O and are taken as positive in
the direction of ray of light)
\therefore\hspace15mm \frac{2.5}{X}=\frac{0.5}{R}
\therefore\hspace15mm X=5R