A concave mirror forms a virtual, erect, and magnified image. Where is the object placed?
A. Between the pole (P) and the focus (F)
B. At the focus (F)
C. Beyond the center of curvature (C)
D. Between the center of curvature (C) and the focus (F)
Answer: Option A
Solution (By JKSSB Mock Tests)
A concave mirror forms real and inverted images in most positions. The only exception is when the object is placed very close to the mirror, specifically between the pole (P) and the principal focus (F). In this position, the reflected rays diverge, forming a virtual, erect, and magnified image behind the mirror. This is why concave mirrors are used as shaving or makeup mirrors.
Explanation:
Law of conservation of energy states total energy (all forms) is conserved in isolated systems. For mechanical energy (KE + PE) to be conserved, only conservative forces (like gravity, spring) must act; non-conservative forces (friction) convert mechanical energy to heat. Option C precisely states this condition. Options A and B are incorrect as KE and PE individually vary. Option D is false as thermal energy can exist. Memory tip: 'Mechanical energy conserved ⇔ no non-conservative work'. This nuanced understanding is critical for energy problems in competitive exams, where distractors often omit the conservative force condition.
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