PSU Sample Paper 2

1. Three 100W non-inductive resistors, when connected in star across 400 V, 50 Hz, 3 phase consumes 1600 W.  When one of the resistances becomes open, the power consumption is reduced by:

a)         half                  b)         one third          c)         two third          d)         one fourth

2. The power input to a three phase induction motor is 62 kW.  The stator loss is 2 kW.  If the rotor is running with a slip of 5%, the total copper loss in the rotor will be:

a)         500 W              b)         1000 W            c)         1500 W            d)         3000 W

3. A transformer has an iron loss of 250 W and full-load copper loss of 1000 W.  At what percentage of full-load, the efficiency becomes maximum:

a)         70%                 b)         66%                 c)         50%                 d)         25%

4. Operational amplifier can amplify:

a)         AC signals only                                   b)         DC signals only
c)         Both AC and DC signals                     d)         All of the above

5. Adjacent channel rejection of a receiver is determined by its:

a)         Fidelity             b)         Noise figure     c)         Selectivity       d)         Sensitivity

6. In a three input NAND gate, one input is low.  The output will be:

a)         Low                                         b)         Will depend upon other two inputs
c)         High                                         d)         None of the above

7. If the conduction in the anode circuit takes place for less than 180o of the input cycle, the amplifier is classified as:

a)         Class A            b)         Class B            c)         Class C           d)         Super Class

8. 500 MHz falls in the;

a)         HF Band                                  b)         VHF Band
c)         UHF Band                               d)         SHF Band

9. The signals sent by the TV transmitter to ensure correct scanning in the receiver are called:

a)         Sync                b)         Chroma           c)         Luminance      d)         Video

10. A frequency modulated signal, which is modulated by a 3 kHz sine wave swings between 100.02 MHz and 99.98 MHz.  The modulation index of the signal will be:
            a)         20/3                 b)         40/3                 c)         10/3                 d)         5/3

ANSWERS    PSU Sample Question Papers 2

1. A      2. D     3. C     4. D     5. C     6. C     7. D     8. C     9. C     10. A