Vikram Sarabhai Space Centre Technical Assistant Electronics Paper 2019
VSSC Technical Assistant/Scientific Assistant/Library Assistant exam is scheduled to be conducted on 30th July 2023 in Thiruvananthapuram. If you are the aspirants of the said exam, then you must read this question paper for practice.
| 1 | In a three phase balanced star connected system, the phase relationship between line voltage and the respective phase voltages is
(a) Line voltage leads phase voltage by 30 degree (b) Line voltage lags phase voltage by 30 degree (c) Line voltage leads phase voltage by 120 degree (d) Line voltage lags phase voltage by 120 degree |
| 2 | Two voltage sources of open circuit voltage of 10 V and 12 V with internal resistance 2 Ohms and 3 Ohms respectively are connected in parallel with like terminals shorted together. What is the effective open circuit voltage of the combination?
(a) 10 V (b) 12 V (c) 11 V (d) 10.8 V |
| 3 | Which of the following is false for a continuous time signal?
(a) Any signal can be expressed as the sum of an odd and an even signals (b) Sum of two periodic signals is always periodic (c) Any periodic signal can be expressed as sum of sinusoidal signals (d) None of the above |
| 4 | The built in potential of a P N Junction diode is 0.7 V at room temperature. What will be the approximate value of built in potential if the doping concentrations on both sides are doubled? Assume In(2) = 0.7
(a) 0.9846 V (b) 0.7364 V (c) 0.7182 V (d) 0.49 V |
| 5 | Which of the following is ture about a P-MOSFET?
(I) Drain current consists of holes flowing from source to drain (II) To turn ON an enhanced P-MOSFET, gate voltage should be made more positive than source voltage atleast by magnitude of threshold voltage (III) The transconductance is directly proportional to oxide thickness (a) I only (b) I & II only (c) I & III only (d) II & III only |
| 6 | Which of the following is FALSE about compensating an operational amplifier?
(a) Used to stabilize the opamp in negative feedback operations (b) Establishes a dominant pole at low frequency (c) May make use of Miller effect to realize large effective capacitances internally (d) Increases the bandwith of the operational amplifier |
| 7 | In an amplitude modulated sytem, a sinusoidal carrier signal of 1 MHz is modulated by a 10 kHz sinusoidal signal. If the lower side band and the carrier are suppressed and if the amplitude modulated signal is sampled for further processing, what should be the minimum sampling frequency for base band sampling?
(a) 1000 kHz (b) 990 kHz (c) 1980 kHz (d) 2020 kHz |
| 8 | A super heterodyne receiver with an intermediate frequency of 450 kHz is tuned to a signal of 1600 kHz. The image frequency is
(a) 2500 kHz (b) 2050 kHz (c) 1600 kHz (d) 450 kHz |
| 9 | A 240V single phase AC supply is fed to a load resistor of 100 Ohms through a thyristor. If the thyristor is fired at 90 degree, what is the power consumed by the load?
(a) 144 W (b) 432 W (c) 576 W (d) 000 W |
| 10 | A 4 bit Digital to Analog converter (DAC) gives an output voltage of 5 V for an input code of 1111. What is the output voltage for an input code of 1100?
(a) 1 V (b) 2 V (c) 3 V (d) 4 V |
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