COMEDK · Physics · 25. Ray Optics
A beam of parallel rays is brought to a focus by a plano-convex lens. A thin concave lens of the same focal length is joined to the first lens. The effect of this is
- A the focal point shifts away from the lens by a small distance
- B the focus remains undisturbed
- C the focus shifts to infinity
- D the focal point shifts towards the lens by a small distance
Answer & Solution
Correct Answer
(C) the focus shifts to infinity
Step-by-step Solution
Detailed explanation
The combined focal length of plano-convex lens is \[ \frac{1}{f}=\frac{1}{f_{1}}+\frac{1}{f_{2}} \] where, \(f_{1}=\infty\) for the plane surface and \(f_{2}=f\)…
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