Solve question 5

5.  The adjacent figure shows cross section of a hollow glass tube of internal radius r, external radius R and index of refraction n. For two rays DE and ABC (in which DE lies on ODE and DE is parallel to BC), the separation r1 will be
 
( A )   r 1   =   n   -   1 R                                                           ( B )   r 1 =   n 2 R                                                                             ( C )   r 1   =   n r                                                                   ( D )   r 1   =   n 2 r

Dear student,

  • 5
correct answer is c
apply snell's law at the outer surface, u will get sin B= nr/R(B is the angle of refraction on going out from the tube)
then r1=RsinB=nr
  • 2
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