AIIMS 2011
- Exam
- AIIMS
- Year
- 2011
- Subject
- Physics
- Chapter
- Ray Optics
AIIMS 2011 · Physics · Ray Optics
Assertion : Magnification of a convex mirror is always positive,...
Assertion : Magnification of a convex mirror is always positive, but that of a concave mirror may be both positive or negative.
Reason : It depends on the sign convention chosen.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIf both assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
Step-by-step solution
The sign of magnification depend on the sign convention chosen. According to the new Cartesian sign conventions, magnification for a convex mirror is positive because image formed by a convex mirror is always virtual and erect. A concave mirror can form virtual or erect images and also real, inverted images. In the latter case, its magnification becomes negative. The reason though correct does not explain the assertion properly.