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Light – Reflection and Refraction — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceLight – Reflection and Refraction5 Marks
Question
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
  1. What is the nature of spherical mirror?
  2. Why is a hole burnt in the carbon paper?
  3. At which point of the spherical mirror the carbon paper is placed?
  4. What name is given to the distance between spherical mirror and carbon paper?
  5. What is the advantage of using a carbon paper rather than a white paper?
✓

Answer

  1. The spherical mirror is concave.
  2. A concave mirror converges light rays, and in this case it will converge the incoming parallel rays of the sun at its focus. Since the carbon paper was kept at the focus of the concave mirror, the hole was burnt into it. 
  3. The carbon paper was kept at the focus of the spherical mirror.
  4. The distance between the mirror and the carbon paper is the focal length.
  5. A carbon paper is a good absorber of sunlight; hence, it burnt quickly.​

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