PHYSICS SECTION C

                1.   What is the difference between a CFL and a LED lamp?

1.       To produce light, a CFL uses mercury vapour and phosphor while a LED lamp uses semiconductor material.

2.       The average life span of a CFL is much longer than that of a LED lamp.

3.       A CFL is less energy – efficient as compared to a Led lamp.

Which of the statements given above is/ are correct?

(a)    Only 1

(b)   2 and 3

(c)     1 and 3

(d)   1, 2 and 3

2.  A new optical disc format known as the Blu-ray Disc (BD) is becoming popular; in what way is it different from the traditional DVD?

1.       DVD supports standard definition video while BD supports high definition video.

2.       Compared to a DVD, the BD format has several times more storage capacity.

3.       Thickness of BD is 2.4 mm while that of DVD is 1.2 mm.

While of the statements given above is / are correct?

(a)    Only 1

(b)   1  and 2

(c)    2 and 3

(d)   All of these

              3. “The stars seem to be higher on the sky than they actually are”. This can be explained by

(a)    Atmospheric refraction

(b)   Dispersion of light

(c)    Diffraction of light

(d)   Total internal reflection

                 4.   A spherical air bubble is embedded in a piece of glass. For a ray of light passing thorugh the bubble, it behave like a

(a)    Converging lens

(b)   Diverging lens

(c)    Plano- converging lens

(d)   Plano- diverging lens

               5. An iron ball and a wooden ball of the same radius are released from a height H’ in vacuum. The time taken to reach the ground will be

(a)    More for the iron  ball

(b)   More for the wooden ball

(c)    Equal for both

(d)   Equal for both

(e)   I the ratio of their weights

                6.  The black board seems black because, it

(a)    Reflects every colour

(b)   Does not reflect any colour

(c)    Absorbs black colour

(d)   Reflects black colour

                  7. Match the followings lists

List I (magnet)	List II (property )
A.      Artificial magnet        B.      Permanent magnet        C.      Temporary magnet        D.      Earth as a magnet	1.       Long lived        2.       Last for infinitely  long period         3.       Short lived        4.       Induced magnet

       Codes

                                          A      B     C     D

(a)           3      1      4      2

(b)          3      4      1      2

(c)           2      1      4      3

(d)          2      4      1      3

                    8.  A body weights 5 kg on equator. At the poles, it is likely to weigh

(a)    5 kg

(b)   Less than 5 kg but not zero

(c)    0  kg

(d)   More than 5 kg

                    9. The material used for electric fuse is an alloy of tin and lead. This alloy should have

(a)    High specific resistance and low melting point

(b)   Low specific  resistance and high melting point

(c)    Low specific  resistance  and low melting point

(d)   High specific resistance and high melting point.

                    10. When a moving bus suddenly applies brakes, the passengers sitting in it fall in the forward direction. This can be explained by

(a)    The theory of relativity

(b)   Newton’s first law

(c)    Newton’s second law

(d)   Newton’s third law.

                       11.  Bats can ascertain distance, directions nature and size of the obstacles at night. This is possible by reflection of the emitted

(a)    Ultrasonic waves from the bat

(b)   Ultrasonic waves from the distant objects

(c)    Supersonic waves from the bat

(d)   Supersonic waves from the distant objects

              Answer:

1.       C

2.       B

3.       A

4.       B

5.       A

6.       B

7.       C

8.       D

9.       A

10.   B

11.   A