1)Consider a lossless antenna with a directive gain of +6dB. If 1 mW of power is fed to it the total power radiated by the antenna will be
A) 4 mW
B) 1 mW
C) 7 mW
D) 1/4 mW
Answer : (A)

2)The bandgap of Silicon at room temperature is
A) 1.3 eV
B) 0.7 eV
C) 1.1 eV
D) 1.4 eV
Answer : (C)

3) In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noise ratio improves by the factor
A) 8/6
B) 12
C) 16
D) 8
Answer : (C)

4) A device with input x(t) and output y(t) is characterized by: y(t) = x2(t). An FM signal with frequency deviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth of the output signal is
A) 370 kHz
B) 190 kHz
C) 380kHz
D) 95kHz
Answer : (C)

5) For the polynomial P(s) = s5 + s4 + 2s3 + 2s2 + 3s + 15, the number of roots which lie in the right half of the s-plane is
A) 4
B) 2
C) 3
D) 1
Answer : (B)

6) An AM signal is detected using an envelope detector The carrier frequency and modulating signal frequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope detector is
A) 500 msec
B) 20 msec
C) 0.2 msec
D) 1 msec
Answer : (B)

7) In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noise ratio improves by the factor
A) 8/6
B) 12
C) 16
D) 8
Answer : (C)

8) Consider the following statements S1 and S2.
S1: The b of a bipolar transistor reduces if the base width is increased.
S2: The b of a bipolar transistor increases if the doping concentration in the base is increased. Which one of the following is correct?

A) S1 is FALSE and S2 is TRUE
B) Both S1 and S2 are TRUE
C) Both S1 and S2 are FALSE
D) S1 is TRUE and S2 is FALSE
Answer : (D)


Edited by Priya - 04Jan2007 at 4:31pm