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CoCubes Previous Questions in Electronics

Q1.In case of current shunt feedback amplifier, what will happen to the input resistance and output resistance?

  • Input resistance increases and output resistance decreases
  • Input resistance decreases and output resistance increases
  • Both Input resistance and output resistance decreases
  • Both Input resistance and output resistance increases

Ans:Input resistance decreases and output resistance increases


Q2.In a certain transistor, the emitter current is 1.08 times as large as the collector current. If it is known that the emitter current is 10 mA, determine the base current.

  • 0.74 mA
  • 0.46 mA
  • 0.32 mA
  • 0.98 mA

Ans:0.74 mA


Q3.Why does the gain of a BJT drop at high frequencies?

  • Because of the inter-electrode capacitances (transistor capacitances)
  • Because of the early effect
  • Because of the high current effects in the base
  • None of the mentioned options

ans:Because of the inter-electrode capacitances (transistor capacitances)


Q4.For the transistor given below, if  = 50, then determine the value of voltage “VEC“.

  • 6.16 V
  • 8.24 V
  • 3.42 V
  • 10.24 V

Ans: 6.16 V


Q5.Two incandescent light bulbs of 30 W and 50 W rating are connected in series across the supply voltage “V”, then:

  • the bulbs together will consume 80 W
  • the bulbs together will consume 20 W
  • the 50 W bulb glows brighter
  • the 30 W bulb glows brighter

Ans: the 50 W bulb glows brighter


Q6.

Determine the value of “E”

  • -16 V
  • -18V
  • -20V
  • -21V

Ans: -18V


Q7.

Determine resistance across “ab”.

  • 3.24 ohm
  • 6.22 ohm
  • 2.08 ohm
  • 8.22 ohm

Ans:3.24 ohm


Q8.In the following circuit, i1 = 2 sin 4t A and i2 = 5 sin 3t A. Determine the value of “v1“.

  • 32 cos 4t + 15 cos 3t
  • 15 cos 4t + 32 cos 3t
  • 32 cos 3t + 32 cos 2t
  • 32 cos 3t – 15 cos 2t

ans: 32 cos 4t + 15 cos 3t


Q9 Determine the value of “Vx“.

  • -9.6 V
  • -6.8 V
  • -4.2 V
  • -12.3 V

Ans: -12.3 V


Q10.Which of the following signals is used to read the opcode from the data bus and execute it?

  • INTR
  • INTA
  • HLDA
  • (RESET IN)’

Ans:INTA


Q11.If both of the status signals of a 8085 microprocessor are high, then which of the following operations can be performed?

  • Halt
  • Read
  • Write
  • Fetch

Ans: Fetch


Q12.For the given code, if the contents of memory location 4A00H, 4A001H and 4A002H are respectively A8H, 97H and 46H, then after execution of program contents of memory location 4A02H will be:


LXI H, 4A02H
LDA 4A00H
MOV B, A
LDA 4A01H
CMP B
JZ FNSH
JC GRT
MOV M, A
JMP FNSH
MOV M, B
FNSH: HLT

  • A8H
  • 97H
  • 46H
  • None of the mentioned options

Ans :A8H


Q13.For the given code, if the content in the memory location 4400H is 44H before the execution of the program, then content in memory location 4300H after the execution of the program will be:

LDA 4400H
CMA
STA 4300H
HLT

  • BBH
  • AAH
  • ABH
  • BAH

Ans: BBH


Q14.

The given diode logic circuit represents:

  • OR gate
  • NAND gate
  • NOR gate
  • AND gate

Ans OR gate


Q15.The result of adding hexadecimal number A6 to 3A will be:

  • EE
  • DD
  • F0
  • E0

Ans: F0


Q16.The hexadecimal number “A1” has the decimal value equivalent to:
  • 81
  • 161
  • 257
  • 177

Ans: 161


Q17.If the input to T-flip-flop is 120 Hz signal, then the final output of the three T-flip-flops in cascade will be:

  • 15 Hz
  • 18.5Hz
  • 12.5Hz
  • 5oHz

Ans: 15Hz


Q18. The Boolean function realized by the logic circuit shown below will be:

  • F = m(2, 3, 6, 7, 8, 10, 12)
  • F = m(2, 3, 5, 7, 10, 12, 13)
  • F = m(1, 3, 6, 8, 9, 11, 12)
  • F = m(1, 3, 5, 7, 9, 10, 12)

Ans: F = m(2, 3, 6, 7, 8, 10, 12)


Q19.Which of the following modulation schemes is digital in nature?

  • Pulse Amplitude Modulation
  • Pulse Position Modulation
  • Pulse Width Modulation
  • Delta Modulation

Ans: Delta Modulation


Q20.Which of the following statements is/are the disadvantages of time division multiplexing?

I. It has large amount of crosstalk problem.
II. Synchronization is required for proper operation.
III. There are possibilities of loss of TDM signal due to channel noise.

Choose the correct answer from the options given below.

  • Both I and II
  • Both II and III
  • Both I and III
  • I, II and III

Ans:Both II and III

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