InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
A Cassegrain telescope uses two mirrors of radii of curvature 220 mm and 140 mm. The distance b/w the two mirrors is 20 mm. Wherewill the final image of an object at infinity be? |
|
Answer» Solution :By USING the formula for mirrors, `(1)/(f)=(1)/(u)+(1)/(v)` we get Since, `f=r//2=(220)/(2)=110` mm hence, `(1)/(110)=(1)/(oo)+(1)/(v)` `THEREFORE v=110`mm virtual object distance for the second MIRROR `=(110-20)=90` mm For the second mirror, Hence `(1)/(-70)=(1)/(-90)+(1)/(v)` `therefore(1)/(v)=(1)/(-70)+(1)/(90)=(-90+70)/(6300)` or`v= -(6300)/(20)= -315` mm The image is formed at 315 mm from the SMALLER mirror in the direction of light. |
|