In NCERT's sign convention for spherical mirrors, distances are measured
A{'text': 'from the pole, with the incident light travelling along +x', 'label': 'A'}
B{'text': 'from the centre of curvature', 'label': 'B'}
C{'text': 'always positive', 'label': 'C'}
D{'text': 'from the focal point along the principal axis', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'from the pole, with the incident light travelling along +x', 'label': 'A'}
1. NCERT sign convention: pole P is the origin; principal axis is the x-axis.
2. Light travels in the +x direction; distances measured against light are negative.
3. Heights above the axis are positive, below negative.
_Source: NCERT Class 12 Physics Part II, Ch 9 §9.2.1_
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