CEPTAM STA ECE Model Question Paper

DRDO STA CEPTAM Electronics & Telecommunication Model Paper

(1) Measurement of Hall Coefficient enables the determination of-
(a) Temperature coefficient and thermal conductivity
(b) Mobility and concentration of charge carriers
(c) Fermi level and forbidden energy gap
(d) None of these
Ans- (b)
(2) Silicon is not suitable for fabrication of light emitting diodes because it is –
(a) An indirect band gap semiconductor
(b) A direct band gap semiconductor
(c) A wide band gap semiconductor
(d) A narrow band gap semiconductor
Ans- (a)
(3) The band gap of elements arranged in ascending order is
(a) Diamond, Ge, Si
(b) Si, Ge, Diamond
(c) Ge, Si, Diamond
(d) Diamond, Si, Ge
Ans- (c)
(4) For various types of oscillators, the correct statement is
(a) LC oscillators are more stable than crystal oscillators
(b) Crystal oscillators have highest Q
(c) Phase-shift oscillators have the widest range of frequency
(d) Wien bridge oscillator is used where a single frequency oscillator is required
Ans- (b)
(5) For Butterworth & Chebyshev filters, the correct statement is
(a) Butterworth response has a sharp cut-off
(b) Chebyshev response has a flat response in the pass band
(c) Butterworth response hase ripples in the pass band
(d) Chebyshev response has ripples in the pass band
Ans- (d)
(6) In a fullwave rectifier circuit with centre tap transformer, if voltage between one end of secondary winding and centre tap is 300V peak, then PIV (peak inverse voltage) is
(a) 300 V
(b) 150 V
(c) 600 V
(d) 900 V
Ans – (c)
(7) The effect of phase error of local oscillator on spectral components in coherent detection of SSB Amplitude modulated signal is
(a) The frequency of demodulated signals varies with fiexed amplitude
(b) Amplitude of demodulated signals varies with fixed frequency
(c) Both amplitude & frequency vary
(d) The recovered signal has phase offset with fixed amplitude
Ans- (d)
(8) The maximum transmission power efficiency of DSB-C Amplitude modulation is
(a) 25%
(b) 33.33%
(c) 50%
(d) 100%
Ans- (b)
(9) Minimum number of bits required to represent maximum value of given analogue signals with 0.1% accuracy is
(a) 8 bits
(b) 9 bits
(c) 10 bits
(d) 12 bits
Ans- (b)
(10) If a right hand circularly polarised wave is incident on a perfect conductor. The reflected wave is
(a) Left circularly polarised wave
(b) Linear polarised wave
(c) Right circularly polarised wave
(d) None of the above
Ans- (a)
(11) The true statement for wave propagation in rectangular wave guides filled with air is
(a) The phase velocity is equal to velocity of the light in air
(b) The phase velocity is always less than the velocity of light in air
(c) The phase velocity is always more than the velocity of light in air
(d) The pahse velocity is un-defined.
Ans- (c)
(12) As the wave frequency approaches to cut-off frequency of wave guide, the correct statement is
(a) The pahse velocity of waves tends to zero.
(b) The pahse velocity of waves tends to velocity of light
(c) The phase velocity of waves tends to infinite
(d) None of these
Ans- (c)
(13) The gain of a parabolic dish antenna of 1 m diameter and 80% efficiency at 9.5 GHz is
(a) 39 dB
(b) 78 dB
(c) 40 dB
(d) 45 dB
Ans- (a)
(14) To increase gain of a parabolic reflector antenna by 6dBi, the correct statement is (Assuming efficiency 70%)
(a) Diameter is to be increased to 6 folds
(b) Diameter is to be increased to 4 folds
(c) Diameter is to be increased to 2 folds
(d) None of the above
Ans- (c)
(15) The waveguide Magic Tee can be used as
(a) An Isolator
(b) T/R switch in trans-receiver
(c) Adjustable Phase Shifter
(d) All of these
Ans- (d)
(16) The microwave device working on the principal of Faraday rotation is called as
(a) Rotary Joint
(b) Circulator
(c) Isolator
(d) None of these
Ans- (c)
(17) Which of the following devices cannot be used as microwave oscillator
(a) IMPATT diode
(b) PN junction diode
(c) TRPATT diode
(c) BARRITT diode
Ans- (b)
(18) The number of comparators needed in a 8-bit flash type A to D converter is
(a) 8
(b) 16
(c) 255
(d) 256
Ans- (c)
(19) The register in the 8085A that is used to keep track of the memory address of the next op-code to be run in the program is the
(a) Stack pointer
(b) Program counter
(c) Accumulator
(d) None of these
Ans- (b)
(20) The Complement Accumulator (CMA) instruction of 8085 processor on execution affects
(a) Zero Flag
(b) Sign Flag
(c) Carry Flag
(d) None of these flags
Ans- (d)