Q20
3 marksShort AnswerSection A

State the type of mirror preferred as (i) rear view mirror in vehicles, (ii) shaving mirror. Justify your answer giving two reasons in each case.

Light — Reflection and Refraction
Spherical Mirrors
Official Answer

(i) Rear-view mirror in vehicles: Convex mirror.

Justification:

  1. It always gives an erect, though diminished, image of the traffic behind.
  2. It has a wider field of view because it is curved outwards, enabling the driver to see a much larger area than a plane mirror.

(ii) Shaving mirror: Concave mirror.

Justification:

  1. When held close to the face (between the pole and principal focus), it forms an erect image.
  2. The image formed is magnified (enlarged), allowing a detailed and clear view of the face.
convex mirrorerect and diminishedwider field of viewconcave mirrormagnifiederect image when close

Marking Scheme

  • 10.5 marks for identifying Convex mirror for (i).
  • 21.0 mark for providing two valid reasons for (i).
  • 30.5 marks for identifying Concave mirror for (ii).
  • 41.0 mark for providing two valid reasons for (ii).

Hint

Think about which mirror diverges light to show a wider area, and which mirror can magnify an object when placed very close.

Quick Oral Answer

We use a convex mirror as a rear-view mirror because it provides an erect, diminished image with a wider field of view. We use a concave mirror as a shaving mirror because it provides an erect and magnified image when the face is close to it.

Analysis & Explanation

Convex mirrors diverge light rays, which allows them to cover a wider angle of view (field of view), making them ideal for driving safety. Concave mirrors, on the other hand, can form a magnified, virtual, and erect image when the object is placed very close (within its focal length), which is highly useful for shaving or dental examinations.

Common Mistakes

  1. 1Swapping the uses of concave and convex mirrors.
  2. 2Stating that convex mirrors form real or inverted images for rear-view purposes.

Interesting Facts

A large convex mirror is installed in the Agra Fort wall so that visitors can see a complete, full-length view of the distant Taj Mahal.

Spotted a mistake or something unclear?

Tell us — we fix reported answers fast.

Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2012?

This question carries 3 marks in the CBSE Class 10 Science 2012 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 "Spherical Mirrors" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2012 paper?

This is a Short Answer question from Section A in the CBSE Class 10 Science 2012 paper.