SCIENCE AND TECHNOLOGY—2004 (Set III— Compartment Delhi)

Except for the following questions, all the remaining questions. have been asked in Set I and Set II.

Q. 1. A cylinder of a material is 10 cm long and has a cross-section of 2 cm2 If its resistance along the length be 20 ohms, what will its resistivity value be in number and units? 1

Q. 2. The focal lengths of lenses used as objective and eye-piece in a telescope are respectively 1 m and 1 cm. What will be the distance between the two lenses if the telescope is set for normal adjustment position? 1

Q. 3. What is denatured alcohol? 1

Q. 6. State how we can locate the pole star in the sky. 2

Q. 10. An electric appliance draws a current of 0.4 A when the. voltage is 220 volts. Calculate the amount of electric charge flowing through it in one hour. 2

Q. 11. An object 3 cm high is placed at a distance of 24 cm in front of a convex lens of focal length 16 cm. Find the position, nature and size of the image formed. 3
Or
An object 4 cm high is placed at a distance of 6 cm in front of a concave mirror of focal length 12 cm. Find the position, nature and size of the image formed.

Q. 19. a) Express Ohm’s law by a mathematical formula.
b) Draw a circuit diagram to verify Ohm’s law.
c) Present the relationship between the voltage applied across a conductor
and the current flowing through it graphically. 1, 2, 2

Q. 22. Name the scientist who proposed the theory of natural selection.1