Why does a smooth, polished surface look like a mirror but a sheet of paper does not — even though BOTH obey the laws of reflection?
AOn a polished surface, parallel incident rays remain parallel after reflection (regular reflection); on rough paper, parallel rays reflect in different directions (diffused reflection)
BThe paper has different laws of reflection
CSmooth surfaces obey different optics
DPaper does not reflect light at all
Answer & Solution
Correct answer: A. On a polished surface, parallel incident rays remain parallel after reflection (regular reflection); on rough paper, parallel rays reflect in different directions (diffused reflection)
At each point on the paper the laws of reflection are still obeyed; but the surface is microscopically irregular, so the normals at different points face in different directions. Parallel rays therefore scatter off in many directions (diffused reflection). On polished metal/glass the surface is uniform, normals are parallel, so reflected rays stay parallel — that's regular reflection, which forms a clear image.
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