State the types of mirrors used for (i) headlights and (ii) rear view mirrors, in cars and motorcycles. Give reason to justify your answer in each case.

Q: State the types of mirrors used for (i) headlights and (ii) rear view mirrors, in cars and motorcycles. Give reason to justify your answer in each case.

(i) **Headlights of cars and motorcycles**: **Concave mirrors** are used. - **Justification**: The light source (bulb) is placed at the principal focus of the concave mirror. The reflected rays emerge as a powerful, parallel beam of light that travels long distances to illuminate the road ahead. (ii) **Rear-view (wing) mirrors**: **Convex mirrors** are used. - **Justification**: Convex mirrors always form an erect, though diminished, image of the traffic behind. Additionally, because they are curved outwards, they have a much wider field of view, enabling the driver to see a significantly larger area than would be possible with a plane mirror.

Light — Reflection and Refraction

Uses of Spherical Mirrors

Official Answer

(i) Headlights of cars and motorcycles: Concave mirrors are used.

Justification: The light source (bulb) is placed at the principal focus of the concave mirror. The reflected rays emerge as a powerful, parallel beam of light that travels long distances to illuminate the road ahead.

(ii) Rear-view (wing) mirrors: Convex mirrors are used.

Justification: Convex mirrors always form an erect, though diminished, image of the traffic behind. Additionally, because they are curved outwards, they have a much wider field of view, enabling the driver to see a significantly larger area than would be possible with a plane mirror.

concave mirrorparallel beams of lightconvex mirrorerect and diminishedwider field of viewcurved outwards

Marking Scheme

11.5 marks
21.5 marks

Hint

Think about which mirror concentrates light into a straight beam (converging action) and which mirror provides a wide-angle view of the background (diverging action).

Quick Oral Answer

Concave mirrors are used in headlights to produce parallel beams of light. Convex mirrors are used as rear-view mirrors because they give an erect image and a wider field of view.

Analysis & Explanation

Based on the NCERT text:

Section 9.2.1 (Uses of concave mirrors) states they are used in headlights to get powerful parallel beams.
Section 9.2.2 (Uses of convex mirrors) states they are preferred as rear-view mirrors because they give an erect, diminished image and have a wider field of view as they are curved outwards.

Common Mistakes

1Writing 'convex mirror' for headlights and 'concave mirror' for rear-view mirrors.
2Forgetting to mention the 'wider field of view' or 'erect image' when justifying the rear-view mirror.

Interesting Facts

A passenger-side rear-view mirror in many cars has the warning text: 'Objects in mirror are closer than they appear'. This is because the convex mirror diminishes the image to fit a wider field of view, making objects look smaller and thus further away than they actually are.

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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 "Uses of 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.