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Worksheet 3

The document is a worksheet for students at Vidhya Sagar Global School focusing on the concepts of light, reflection, and refraction through various exercises involving concave and convex mirrors. It includes problems related to image formation, ray diagrams, and the properties of different types of mirrors. The worksheet aims to enhance understanding of optical principles through practical applications and calculations.

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43 views3 pages

Worksheet 3

The document is a worksheet for students at Vidhya Sagar Global School focusing on the concepts of light, reflection, and refraction through various exercises involving concave and convex mirrors. It includes problems related to image formation, ray diagrams, and the properties of different types of mirrors. The worksheet aims to enhance understanding of optical principles through practical applications and calculations.

Uploaded by

minecraftvaringala
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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VIDHYA SAGAR GLOBAL SCHOOL

(AFFILIATED TO CBSE, NEW DELHI)


Chengalpattu – 603 111
WORKSHEET-3

Light – Reflection and Refraction

1. An object 4.0 cm in size, is placed 25.0 cm in front of a concave mirror of


focal length 15.0 cm.
(i) At what distance from the mirror should a screen be placed in order to obtain
a sharp image?
(ii) Find the size of the image.
(iii) Draw a ray diagram to show the formation of image in this case.
2. (a) A concave mirror of focal length 10 cm can produce a magnified real as
well as virtual image of an object placed in front of it. Draw ray diagrams to
justify this statement.
(b) An object is placed perpendicular to the principal axis of a convex
mirror of focal length 10cm. The distance of the object from the pole of the
mirror is 10 cm. Find the position of the image formed.
3. (a) A security mirror used in a big showroom has radius of curvature 5 m. If a
customer is standing at a distance of 20 m from the cash counter, find the
position, nature and size of the image formed in the security mirror.
(b) Neha visited a dentist in his clinic. She observed that the dentist was
holding an instrument fitted with a mirror. State the nature of this mirror and
reason for its use in the instrument used by dentist.
4. (a) To construct a ray diagram we use two rays which are so chosen that it is
easy to know their directions after reflection from the mirror. Use these two rays
and draw ray diagram to locate the image of an object placed between pole and
focus of a concave mirror.
(b) A concave mirror produces three times magnified image on a screen. If
the objects placed 20 cm in front of the mirror, how far is the screen from the
object?
5. (a) If the image formed by a mirror for all positions of the object placed in
front of it is always diminished, erect and virtual, state the type of the mirror
and also draw a ray diagram to justify your
answer. Write one use such mirrors are put to and why?
(b) Define the radius of curvature of spherical mirrors. Find the nature and
focal length of a spherical mirror whose radius of curvature is +24 cm.
6. (a) Define the following terms in the context of spherical mirrors:
(i) Pole
(ii) Centre of curvature
(iii) Principal axis
(iv) Principal focus
(b) Draw ray diagrams to show the principal focus of a
(i) Concave mirror
(ii) Convex mirror
(c) Consider the following diagram in which 𝑀 is a mirror and 𝑃 is an
object and 𝑄 is its magnified image formed by the mirror. State the type of the
mirror 𝑀 and one characteristic property of the image 𝑄.
7. It is desired to obtain an erect image of an object, using concave mirror of
focal length of 12 cm.
(i) What should be the range of distance of a object placed in front of the
mirror?
(ii) Will the image be smaller or larger than the object? Draw ray diagram to
show the formation of image in this case.
(iii) Where will the image of this object be, if it is placed 24 cm in front of the
mirror? Draw ray diagram for this situation also to justify your answer.
Show the positions of pole, principal focus and the centre of curvature in the
above ray diagrams.
8. Suppose you have three concave mirrors 𝐴, 𝐵 and 𝐶 of focal lengths 10 cm,
15 cm and 20 cm. For each concave mirror you perform the experiment of
image formation for three values of object distances of 10 cm, 20 cm and 30
cm. By giving reason, answer the following:
(a) For the three object distances, identify the mirror/mirrors which will form an
image of magnification -1.
(b) Out of the three mirrors, identify the mirror which would be preferred to be
used for shaving purposes/make up.
(c) For the mirror 𝐵 draw ray diagram for image formation for object distances
10 cm and 20 cm.
9. A student has focused the image of a candle flame on a white screen using a
concave mirror. The situation is a given below:
Length of the flame = 1.5 cm
Focal length of the mirror = 12 cm
Distance of flame from the mirror = 18 cm
If the flame is perpendicular to the principal axis of the mirror, then calculate
the following:
(a) Distance of the image from the mirror
(b) Length of the image
If the distance between the mirror and the flame is reduced to 10 cm, then
what would be observed on the screen? Draw ray diagram to justify your
answer from this situation.
10. A student wants to project the image of a candle flame on the walls of
school laboratory by using a mirror.
(a) Which type of mirror should he use and why?
(b) At what distance in terms of focal length ' 𝑓 ' of the mirror should he place
the candle flame so as
to get the magnified image on the wall?
(c) Draw a ray diagram to show the formation of image in this case.
(d) Can he use this mirror to project a diminished image of the candle flame on
the same wall? State 'how' if your answer is 'yes' and 'why not' if your answer
is 'no'

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