Electronic Devices

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A full wave rectifier circuit with diodes (D_1) and (D_2) is shown in the figure. If input supply voltage V_in = 220(100π t) volt, then at t = 15 msec Answer: 1. D₁ is forward biased, D₂ is reverse biased or 2. D₁ is reverse biased, D₂ is forward biased Key idea: in a centre-tapped full-wav... Diode as a rectifier 1 answer
The output (Y) of the given logic implementation is similar to the output of an/a ________ gate. Answer: 4. NOR Key idea: write the output of each gate in Boolean form and simplify. The upper gate is a NOR gate with inputs A and B: A+B .... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
A logic circuit provides the output Y as per the following truth table :| A | B | Y ||---|---|---|| 0 | 0 | 1 || 0 | 1 | 0 || 1 | 0 | 1 || 1 | 1 | 0 |The expression for the output Y is : Answer: 4. B Key idea: Read the truth table to see what Y depends on. Y is 1 when B=0 and 0 when B=1 , whatever A is (rows 1 and 3, and rows... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
Consider the following statements A and B and identify the correct answer :A. For a solar-cell, the I-V characteristics lies in the IV quadrant of the given graph.B. In a reverse biased pn junction diode, the current measured in (μ A), is due to majo… Answer: 2. A is correct but B is incorrect. Key idea: Check each statement separately. A: A solar cell works as a generator, so its I-V curv... LED, photodiode and solar cell 1 answer
The output (Y) of the given logic gate is similar to the output of an/a : Answer: 1. AND gate Key idea: Find the output of each first-stage gate, then apply the final NOR gate. With the inputs of each gate joined,... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
For the following logic circuit, the truth table is: Answer: 3. A B Y: 0 0 0; 0 1 1; 1 0 1; 1 1 1 The inputs A and B pass through NOT gates, and the results go into a NAND gate. Y=bar A·bar B=A... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
A full wave rectifier circuit consists of two p-n junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output? Answer: 4. Capacitor The rectifier output is pulsating dc. A capacitor connected across the load charges at the peaks and discharges in the... Diode as a rectifier 1 answer
Given below are two statements:Statement I : Photovoltaic devices can convert optical radiation into electricity.Statement II : Zener diode is designed to operate under reverse bias in breakdown region.In the light of the above statements, choose the… Answer: 2. Both Statement I and Statement II are correct. Statement I is correct: photovoltaic devices (solar cells) convert optical radiati... LED, photodiode and solar cell 1 answer
The truth table for the given logic circuit is : Answer: 4. Truth table (A B C): 0 0 1; 0 1 0; 1 0 1; 1 1 0 Trace the circuit. The upper NAND gets A and B: Y₁=A· B . The lower NAND gets bar... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
In half wave rectification, if the input frequency is 60 Hz, then the output frequency would be : Answer: 4. 60 Hz A half-wave rectifier conducts only in one half of each ac cycle, so there is one output pulse per input cycle. Output freq... Diode as a rectifier 1 answer
In the given circuits (a), (b) and (c), the potential drop across the two p-n junctions are equal in : Answer: 1. Both circuits (a) and (c) Two diodes in series with a battery see the same current, so their voltage drops are equal when both ar... p-n junction diode I-V characteristics 1 answer
For the given circuit, the input digital signals are applied at the terminals A, B and C. What would be the output at the terminal y ? Answer: 3. Output waveform (3): constant 5 V Key idea: from the circuit, y=A· B+B· C (AND of A,B ORed with NAND of B,C). IntervalABCA.BNAND(... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
The electron concentration in an n-type semiconductor is the same as hole concentration in a p-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them. Answer: 3. current in n-type > current in p-type. Key idea: I∝ n μ E , and the same concentration means the current depends on mobility. In... Semiconductors 1 answer
Consider the following statements (A) and (B) and identify the correct answer.(A) A zener diode is connected in reverse bias, when used as a voltage regulator.(B) The potential barrier of p-n junction lies between 0.1 V to 0.3 V. Answer: 3. (A) is correct and (B) is incorrect. Key idea: a Zener diode regulates voltage only in reverse-bias breakdown, and the barrier po... Zener diode as voltage regulator 1 answer
For the logic circuit shown, the truth table is :(figure: A and B each pass through a NOT gate; both outputs feed a NOR-type gate (OR gate with output bubble) giving Y) Answer: 1. A B Y: 00->0, 01->0, 10->0, 11->1 From the figure, each input goes through a NOT gate, and the outputs feed a NOR gate (OR with a... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
The increase in the width of the depletion region in a p-n junction diode is due to : Answer: 2. reverse bias only In reverse bias, the applied voltage adds to the barrier. Majority carriers are pulled away from the junction,... p-n junction diode I-V characteristics 1 answer
For transistor action, which of the following statements is correct ? Answer: 4. The base region must be very thin and lightly doped. For transistor action the base must be very thin and lightly doped, so most... Semiconductors 1 answer
The correct Boolean operation represented by the circuit diagram drawn is : Answer: 3. NAND In the circuit the two switches A and B are in series between the LED node and ground. Taking the switch position 1 as close... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
For a p-type semiconductor, which of the following statements is true ? Answer: 2. Holes are the majority carriers and trivalent atoms are the dopants. A p-type semiconductor is made by doping silicon or germaniu... Semiconductors 1 answer
In the combination of the following gates the output Y can be written in terms of inputs A and B as Answer: 3. A·B+A· B Read the figure: the upper AND gate gets A and overline B ; the lower AND gate gets overline A and B . An OR gate joins... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
In a p-n junction diode, change in temperature due to heating Answer: 4. affects the overall V - I characteristics of p-n junction Heating changes the number of thermally generated electron-hole pairs,... p-n junction diode I-V characteristics 1 answer
In the circuit shown in the figure, the input voltage V_i is 20 V, V_BE = 0 and V_CE = 0. The values of I_B, I_C and β are given by Answer: 4. I_B = 40 μ A, I_C = 5 mA, β = 125 From the figure: R_B=500\ kΩ , R_C=4\ kΩ , supply 20 V, V_i=20 V, with V_BE=0 and V_CE=0 . I_B=... Semiconductors 1 answer
Which one of the following represents forward bias diode ? Answer: 4. diode with 0 V on left, R, -2 V on right Key idea: a diode is forward biased when its p-side (the triangle base) is at higher pot... p-n junction diode I-V characteristics 1 answer
The given electrical network is equivalent to : Answer: 2. NOR gate Key idea: trace the logic step by step. First gate is a NOR: output A+B . Second gate is a NOR with both inputs joined,... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer

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