Friday, May 15, 2015

Tough Electronics engineering questions

Tough Electronics engineering questions
Electronics and communication engineering core questions
1. If the height of transmitting and receiving antennas in a LOS system are 49 m and 9 m respectively then the distance up to which communication may be possible is about
(a) 40km
(b) 110 km
(c)400 km
(d) 1100 km
2. The skip distance is
(a) same for each layer
(b) independent of frequency
(c) independent of the state of ionisation
(d) independent of transmitted power
3. Match List I (Instrument) with List II (Property/use) and select the correct answer using the codes given below the Lists:
Listi List II
A. PMIVIC 1. Square law type scale
B. Moving iran 2. Very good high frequency response
C. Thermocouple 3. Linear scale over the entire range
D. Electrostatic type 4. Voltmeter
Codes:
A B C D
(a) 4 1 2 3
(b) 3 2 1 4
(c) 4 2 1 3
(d) 3 1 2 4
4. A coil would behave as
(a) an inductor at high frequencies
(b) a capacitor at very low frequencies
(c) a capacitor at very high frequencies
(d) a resistor at high frequencies
5. An ammeter of range 0—25 A has a guaranteed accuracy of 1% of full-scale reading. The current measured by the ammeter is 5A. The limiting error in the reading is
(a) 2%
(b) 2.5%
(c)4%
(d)5%
6. An inductor tunes at 200 KHz with 624pF capacitor and at 600 KHz with 60.4pF capacitor. The self-capacitance of the inductor would be
(a) 8.05 pF
(b) 10.05 pF
(c) 16.l0 pF
(d) 20.l0 pF
7. “The current internationally recognised unit of time and frequency is based on the cesium clock, which gives an accuracy better than 1 micro s per day.” This statement is related to
(a) Working standards
(b) International standards
(c) Primary standards
(d) Secondary standards
8. The bandwidth of a CR0 is from 0 to 20 MHz. The fastest rise time which a square wave can have, in order that it is accurately reproduced by the CR0 is
(a)0.175micro
(b) 17.5ns
(c) 35ns
(d) 52.5ns
9. A dc voltage of 1 V is applied to the X-plates of a CR0 and an ac voltage 2 sin 100 t is applied to the Y-plates. The resulting display on the CR0 screen will be a
(a) vertical straight line
(b) horizontal straight line
(c) sine wave
(d) slant line
10. In a distortion factor meter, the filter at the front end is used to suppress
(a) odd harmonics
(b) even harmonics
(c) fundamental component
(d) dc component
11. Wagner’s earth in ac bridge circuits is used to eliminate the effect of
(a) stray electrostatic fields
(b) stray electromagnetic fields
(c) inter-component capacitances
(d) parasitic capacitance to earth
12. Radiation pyrometers are used for the measurement of temperature in the range
of
(a) 2000 to 500°C
(b) 0°C to 500°C
(c) 500°C to 1200°C
(d) 1200°C to 2500°C
13. Magnetic flux can be measured by
(a) capacitive pick-up
(b) inductive pick-up
(c) resistive pick-up
(d) Half-effect pick-up
14. A semiconductor based temperature transducer has a temperature coefficient of
-2500 microV/ C. This transducer is indeed a
(a) thermistor
(b) forward-biased pn junction diode
(c) reverse-biased pn junction diode
(d) FET
15. The function of the reference electrode in a pH meter is to
(a) produce a constant voltage
(b) provide temperature compensation
(c) provide a constant current
(d) measure average pH value
16. The most light sensitive transducer for conversion of light into electrical power
is the
(a) Photodiode
(b) solar cell
(c) Photoconductive cell
(d) photovoltaic cell
17. In an amplitude modulated system, if the total power is 600 W and the power in
carrier is 400 W, then the modulation index is
(a) 0.5
(b) 0.75
(c) 0.9
(d) 1
18. Time division multiplexing requires
(a) constant data transmission
(b) transmission of data samples
(c) transmission of data at random
(d) transmission of data of only one measurand
19. The dual of a parallel R-C circuit is a
(a series R-C circuit
(b) series R-L circuit
(c) parallel R-C circuit
(d) parallel R-L circuit
20. The function s+2+ 3/s can be realized
(a) both as a driving, point impedance and as a driving point admittance
(b) as an impedance, but not as an admittance
(c) as an admittance, but not as an impedance
(d) neither as an impedance nor as an admittance
Answer:
1 a
2 d
3 d
4 c
5 d
6 b
7 c
8 b
9 a
10 c
11 b
12 d
13 d
14 b
15 a
16 d
17 d
18 a
19 b
20 a

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