Old Questions on Diploma Electrical Engineering

1. Minimum number of J-K flip-flops needed to construct a BCD counter is
(a) 2
(b) 3
(c) 4
(d) 5

2. Consider the following
Any combination circuit can be built using
(1) NAND gates
(2) NOR gates
(3) EX-OR gates
(4) Multiplexers
Which of these are correct?
(a) 1, 2 and 3
(b) 1, 3 and 4
(c) 2, 3 and 4
(d) 1, 2 and 4

3. Shifting a register to the left by one bit position is equivalent to (in Binary code)
(a) Division by 2
(b) Multiplication by 2
(c) Addition of 2
(d) Subtraction of 2

4. The flip flop used in shift register are generally
(a) SR flip-flop
(b) JK flip-flop
(c) D flip-flop
(d) T flip-flop

5. In an 8085 microprocessor system with memory mapped I/O
(a) I/O devices have 16 bit addresses
(b) I/O devices are accessed using IN and OUT instruction
(c) there can be a maximum of 256 input devices and 256 output devices
(d) arithmetic and logic operations can be directly performed with the I/O data

6. The stack pointer in the 8085 microprocessor is a
(a) 16 bit register that point to stack memory locations
(b) 16 bit accumulator
(c) memory location in the stack
(d) flag register used for the stack

7. In 8085 microprocessor system, the direct addressing instruction is
(a) MOV A, B
(b) MOV B, 0AH
(c) MOV C, M
(d) STA addr

8. What is the memory word addressing capability in 8085?
(a) 32 K
(b) 64 K
(c) 256 K
(d) 512 K

9. Which one of the following is NOT a vectored interrupted?
(a) TRAP
(b) INTR
(c) RST 3
(d) RST 7.5

10. The number of hardware interrupts (which require an external signal to interrupt) present in an 8085 microprocessor
(a) 1
(b) 4
(c) 5
(d) 15

11. The synchronisation between microprocessor and memory is done by
(a) ALE signal
(b) HOLD signal
(c) READY signal
(d) None of these

12. A typical cell, for a dynamic RAM can be implemented by using how many MOS transistor?
(a) Six
(b) Five
(c) One
(d) Two

13. In the 8085 microprocessor, the RST6 instruction transfers the program execution to the following locations
(a) 30H
(b) 24H
(c) 48H
(d) 60H

14. If the accumulator of an Intel 8085 A microprocessor contains 37 H and the previous operation has set the carry flag, the instruction ACI 56 H will result in
(a) 8E H
(b) 94 H
(c) 7E H
(d) 84 H

15. How many times will the following loop be executed?
LXI B, 0010 H
Select the correct answer using the code given above:
(a) 10
(b) 100
(c) 16
(d) 15

16. The instruction that does not clear the accumulator of 8085 is
(a) XRA A
(b) ANI 00H
(c) MVI A, 00H
(d) None of these

17. Which of the following interrupts has the lowest priority?
(a) RST 5.5
(b) RST 7.5
(c) TRAP
(d) INTR

18. Addition of two periodic signals will always be
(a) Periodic
(b) Aperiodic
(c) May or may not be periodic
(d) Insufficient data

19. In a communications system, noise is most likely to affect the signal
(a) at the transmitter
(b) in the channel
(c) in the information sources
(d) at the destination

20. The modulation index of an AM wave is changed from 0 to 1. The transmitted power is
(a) unchanged
(b) halved
(c) doubled
(d) increased by 50 percent

21. A 50.004 MHz carrier is to be frequency modulated by a 3 KHz audio tone resulting in a narrow band FM signal. Determine the bandwidth of the FM signal
(a) 2 KHz
(b) 4 KHz
(c) 6 KHz
(d) 4 MHz

22. Which of the following pulse modulation systems is analog?
(a) PCM
(b) Differential PCM
(c) PWM
(d) Delta

23. A television signal is sampled at a rate of 20% above the Nyquist rate. The signal has a bandwidth of 6 MHz. The samples are quantized into 1024 levels. The minimum bandwidth required to transmit this signal would be
(a) 72 M bits/sec
(b) 144 M bits/sec
(c) 72 k bits/sec
(d) 144 K bits/sec

24. If the number of bits per sample in PCM system is increased from n to n+1, then the improvement in signal to quantization noise ratio will be
(a) 3 dB
(b) 6 dB
(c) 2n dB
(d) 0 dB

25. The output of the vertical amplifier applied to the yoke in a TV receiver consists of
(a) direct current
(b) amplified vertical sync pulses
(c) a sawtooth voltage
(d) a sawtooth current

More Question Set on Electrical Engineering Diploma MCQs from Various Exam

Model Question Old Question
Sample Papers Mock Test
Practice Set Question Bank
Important Questions Test Papers
Typical Questions Selected Questions

26. A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The Image frequency is
(a) 750 kHz
(b) 900 kHz
(c) 1650 kHz
(d) 2100 kHz

27. On increasing the number of pulse in rectification the form factor, ripple frequency and efficiency
(a) all increase
(b) decrease, decrease and increase respectively
(c) decrease, increase and increase respectively
(d) increase, decrease and increase respectively

28. A gate turn off (GTO) thyristor
(a) Requires a special turn off circuit like a thyristor
(b) Can be turned off by removing the gate pulse
(c) Can be turned off by a negative current pulse at the gate
(d) Can be turned off by a positive current pulse at the gate

29. In a three phase full wave a.c. to d.c. converter, the ratio of output ripple frequency to the supply voltage frequency is
(a) 2
(b) 3
(c) 6
(d) 12

30. In a 3 phase full converter, the output voltage during overlap is equal to
(a) Zero
(b) Source voltage
(c) Source voltage minus the inductance drop
(d) Average value of the conducting phase voltages

31. Which of the following devices should be used as a switch in a low power switched mode power supply (SMPS)?
(a) GTO

32. In dc choppers, per unit ripple is maximum when duty cycle a is
(a) 0.1
(b) 0.3
(c) 0.5
(d) 0.7

33. Which of the following characteristics are possessed by IGBT
1. High input impedance
2. Secondary discharge problem
3. Current controlled device
4. Low switching loss
5. Faster than BJT
(a) 1, 4 and 5
(b) 1, 2 and 4
(c) 2, 3 and 5
(d) 1, 3 and 5

34. In a three phase voltage source inverter operating in square wave mode, the output line voltage is free from
(a) 3rd harmonic
(b) 7th harmonic
(c) 11th harmonic
(d) 13th harmonic

35. In single pulse modulation of PWM inverters, the pulse width is 1200. For an input voltage of 220 V dc, the r.m.s value of output voltage is
(a) 179.63 V
(b) 254.04 V
(c) 127.02 V
(d) 185.04 V

36. A step up chopper has source voltage 50 V and output 100 V. If the pulse width is 10 μsec, the chopping frequency will be
(a) 50 KHz
(b) 100 KHz
(c) 5 KHz
(d) 10 KHz

37. Power electronic device with poor turn off gain is
(a) a symmetrical thyristor
(b) a conventional thyristor
(c) power bipolar junction transistor
(d) gate turn off thyristor

38. In a thyristor controlled reactor, the firing angle of thyristor is to be controlled in the range of
(a) 00 to 900
(b) 00 to 1800
(c) 900 to 1800
(d) 900 to 2700

39. If the system specifications are given in time domain, best approach for designing is
(a) Nyquist plot
(b) Bode plot
(c) Root locus
(d) Any of these

40. Signal flow graph is used to obtain
(a) stability of a system
(b) transfer function of a system
(c) controllability of a system
(d) absorbability of a system

41. As compared to a closed-loop system, an open-loop system is
(a) more stable as well as more accurate
(b) less stable as well as less accurate
(c) more stable but less accurate
(d) less stable but more accurate

42. Which compensator is used to increase the damping of a badly under-damped system?
(a) Phase-lag
(b) Phase-lead
(c) Phase lag-lead
(d) None of these

43. In pneumatic systems, electrical capacitance is analogous to
(a) restriction to flow
(b) volume of air
(c) filled helical tube
(d) none of these

44. Transformer cores are laminated to reduce
(a) eddy current loss
(b) hysteresis loss
(c) both eddy current and hysteresis loss
(d) ohmic loss

45. Oil in transformer is used for
(a) lubrication purpose
(b) insulation
(c) cooling
(d) both (b) and (c)

46. The open circuit test on a transformer is mainly carried out to determine
(a) copper loss
(b) core loss
(c) total loss
(d) insulation resistance

47. While conducting short-circuit test on a transformer, which side is generally short-circuited?
(a) H.V. side
(b) L.V. side
(c) Primary side
(d) Secondary side

48. Direction of rotation of rotor in a d.c. motor is given by
(a) Faraday’s law
(b) Fleming’s right hand rule
(c) Fleming’s left hand rule
(d) Lenz’s law

49. A d.c. series motor should not be started without a load on it because
(a) it will not run at no load
(b) it may develop excessive speed at no-load and thus damage itself
(c) excessive sparking will occur at commutator
(d) the staring current will be very high

50. Which of the following plants has the minimum running cost?
(a) Nuclear
(b) Thermal
(c) Hydro
(d) diesel