8. Two resistors producing noise voltages of 30 IN and 40 ItV are placed in series. The total noise voltage across the terminals of this series circuit is
A.70
B.1.33
C.17.1
D.50

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9. One major difference between shot and thermal noise is that shot noise is
A. present in vacuum tubes but thermal noise is not
B. idependent of bandwidth whereas thermal noise depends on it
C. associated and dependent on direct current through the device but thermal noise is not
D. directly proportional to electron charge but thermal noise is not

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10. One of the following types of noise becomes of great importance at high frequencies. It is the
A. shot noise
B. agitation
C. flicker noise
D. transit-time noise

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11. The form of 'fading' that produces serious distortion of modulated signal is called fading.
A. interference
B. selective
C. polarisation
D. disturbance

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12. If the input signal-to-noise ratio of a system is 30 and the output signa-to-noise ratio is 3, the noise figure (F) of the system is
A.90
B.10
C.900
D.33

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13. The noise figure of a system is 12 and its input signal-to-noise ratio is 60. The output signal-to-noise ratio of the system is
A.5
B. 1/5
C.72
D.720

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14. A two-stage amplifier with cascaded connection has the following data :Stage-1 Stage-2 noise figure 10 power gain 5 The overall noise figure is
A.16
B.10.33
C.11
D.19

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