Question:
Identify the wrong sign convention
Identify the wrong sign convention
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Virtual image = erect = positive magnification.
Updated On: May 8, 2026
- The magnification for virtual image formed by a convex lens is positive
- The magnification for real image formed by a convex lens is negative
- The height measured normal to the principal axis upwards is positive
- The distances measured in the direction of incident light is positive
- The magnification for virtual image formed by a concave lens is negative
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The Correct Option is
Solution and Explanation
Concept:
Sign convention in optics:
• Upward heights → positive
• Along incident light → positive
• Real image → inverted → negative magnification
• Virtual image → erect → positive magnification
Step 1: Check option (A).
Virtual image by convex lens is erect → magnification positive → correct.
Step 2: Check option (B).
Real image by convex lens is inverted → magnification negative → correct.
Step 3: Check option (C).
Upward direction taken positive → correct.
Step 4: Check option (D).
Distances along incident light are positive → correct.
Step 5: Check option (E).
Concave lens always forms virtual and erect image → magnification is positive, not negative.
Step 6: Conclusion. \[ \boxed{(E)} \]
• Upward heights → positive
• Along incident light → positive
• Real image → inverted → negative magnification
• Virtual image → erect → positive magnification
Step 1: Check option (A).
Virtual image by convex lens is erect → magnification positive → correct.
Step 2: Check option (B).
Real image by convex lens is inverted → magnification negative → correct.
Step 3: Check option (C).
Upward direction taken positive → correct.
Step 4: Check option (D).
Distances along incident light are positive → correct.
Step 5: Check option (E).
Concave lens always forms virtual and erect image → magnification is positive, not negative.
Step 6: Conclusion. \[ \boxed{(E)} \]
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