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CBSE Class 10 Science Solved Question Paper 2016

Short Answer Type

31.

How do Mendel's experiment show that traits are inherited independently?

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32.

An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre ‘O’ of a convex lens of focal length 10 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O’, principal focus F and height of the image on the diagram.

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Long Answer Type

33.

What is placenta? Describe its structure. State its functions in case of a pregnant human female.

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34.

Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution.

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35.

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 an 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.

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36.
(a) Define optical centre of a spherical lens.
(b) A divergent lens has a focal length of 20 cm. At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in above situation.

a. Optical centre is the point lying on the principal axis of a lens through which light passes through without undergoing any deviation.

b. Given,

Focal length, f = -20 cm

Height of the object, h₁ = 4 cm

Image distance, v = -10 cm

To find: Object distance = ?
Size of the image, h₂ = ?

Now, using the lens formula,

Therefore, object is at a distance of 20 cm on the left side of the lens.

Size of the image is given by,

$straight h subscript straight i space equals space straight v over straight u space straight h subscript straight o space space space space equals space fraction numerator negative 10 over denominator negative 20 end fraction space straight x space 4 space space space space equals space 2 space cm$

c) The ray diagram is as given below:

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37.

What is atmospheric refraction? Use this phenomenon to explain the following natural events:

a) Twinkling of stars
b) Advanced sunrise and delayed sunset

Draw diagrams to illustrate your answer.

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