B.    Colour of light           2.   Refractive index of
                                          the medium
     C.    Velocity of light         3.   Amplitude of light
     D.    Propagation of light      4.   Frequency of light
            A         B          C        D
       (a)  2         4          1        3
       (b)  3         4          2        1
       (c)  3         1          2        4
       (d)  4         2          3        1
Ans : (b)
156. A bubble of water shines because of: [IAS 1995]
       (a) reflection
       (b) refraction
       (c) total internal reflection
       (d) None of the above
Ans : (c)
157. One of the youngest sciences of the 20th century which deals with production, control and application of very low temperature
     (approx. below - 150 °C) is called:
       (a) Cryptography
       (b) Crystallograhy
       (c) Cryogenics
       (d) Acarology
Ans : (c)
158. Which of the following is used in a diesel engine?
           1) Cylinder
           2) Sparkplug
           3) Piston
       (a) 1, 2 and 3
       (b) 1 and 2
       (c) 2 and 3
       (d) 1 and 3
Ans : (d)
159. With which of the following instruments can a sailor in a submarine seethe objects on the surface of sea?
       (a) Periscope
       (b) Telescope
       (c) Gyroscope
       (d) Stereoscope
Ans : (a)
160. Match the following: [CDS 1991]
     A. Petrol engine                1.   Compression
     B. Diesel engine                2.   Sparkplug
     C. Ship                         3.   Turboprop
     D. Jet aircraft                 4.   Propeller
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