Q14
3 marksShort AnswerSection A

Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.

Light — Reflection and Refraction
Uses of Spherical Mirrors
Official Answer

(i) Rear-view mirrors:

  • Type of mirror used: Convex mirror.
  • Justification/Reasons:
  1. They always give an erect (though diminished) image, allowing the driver to see the traffic right-side up.
  2. They have a wider field of view because they are curved outwards, enabling the driver to view a much larger area of traffic behind them than would be possible with a plane mirror.

(ii) Shaving mirrors:

  • Type of mirror used: Concave mirror.
  • Justification/Reasons:
  1. When the face is held close to the mirror (between its pole PP and principal focus FF), it forms an erect and enlarged (magnified) virtual image of the face.
  2. The magnification helps in seeing a detailed and clear view of the face for safe and precise shaving.
convex mirrorconcave mirrorerectdiminishedwider field of viewcurved outwardsmagnifiedenlarged

Marking Scheme

  • 1Identifying convex mirror for rear-view and concave mirror for shaving (1 mark)
  • 2Providing two correct reasons for rear-view mirror (erect image, wider field of view) (1 mark)
  • 3Providing two correct reasons for shaving mirror (erect image when close, magnified/enlarged image) (1 mark)

Hint

Think about whether you need a wider view of the background (diminished but covering more area) or a highly detailed, magnified view of a close-up object.

Quick Oral Answer

Convex mirrors are used as rear-view mirrors because they curve outwards, giving a wider field of view and always forming an erect image. Concave mirrors are used as shaving mirrors because they produce a magnified, erect image when the face is close to the mirror.

Analysis & Explanation

According to the NCERT text, convex mirrors are preferred as rear-view mirrors because they are curved outwards, which gives them a wider field of view and always produces an erect, diminished image. Concave mirrors are used as shaving mirrors because when an object is placed close to the mirror (between PP and FF), the image formed is virtual, erect, and magnified, which is ideal for viewing fine details.

Common Mistakes

  1. 1Confusing the uses of concave and convex mirrors.
  2. 2Stating that a concave mirror always forms an inverted image, forgetting that it forms an erect, virtual image when the object is very close (between PP and FF).

Interesting Facts

A large convex mirror is fitted on a wall of Agra Fort facing the Taj Mahal so that visitors can view a complete, full-length image of the distant monument in a small mirror.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2013?

This question carries 3 marks in the CBSE Class 10 Science 2013 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Light — Reflection and Refraction" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Uses of Spherical Mirrors" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2013 paper?

This is a Short Answer question from Section A in the CBSE Class 10 Science 2013 paper.