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Analyse the above table and answer the following questions:
(a) What is the focal length of the concave mirror?
(b) Which set of observations is incorrect and why?
(c) Draw ray diagram to show the image formation for any correct set of observations. 3

Ans. (a) Focal length of concave mirror is – 12 cm.
(b) Case (vi) when u = – 10 cm and v = – 90 cm is incorrect..

So different focal length is observed.
Moreover in this case object distance is less than focal length. In that case image formed will be virtual and behind the mirror.
(c) Ray diagram for Case (iii)
When u = v i.e. object is placed at C. See Q. 2 (Case IV), (L.A.T.),
Chapter 10. [Page 118

Q. 14. Draw a schematic diagram of an electric circuit consisting of a battery of six 2 V cells, a 10  resistor, a 20  resistor, a plug key, all connected in series. Calculate the value of current flowing through the 10  resistor and the power consumed by the 20  resistor.

Ans.

R1 = 10  and       R2 = 20
Resultant resistance, R = R1 + R2
R = 10 + 20 = 30
Total voltage = 12 volts
Total current, I = ?
V = I R
I =

Science 2009 Question Papers Class X
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