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Right CHOICE is (c) 3

Explanation: not (A + not (B)).C) = not (A + not (B)) + not (C)[From De MORGAN’s THEOREM]

 not (A + not (B)).C) = not (A).not (B) + not(C)[From De Morgan’s theorem]

 not (A + not (B)).C) = not (A).B + not (C)

Right ANSWER is (B) 0.060

The explanation is: Given: I0 = 0.095 A

The required equation is ➔ IDC = \(\frac {(2 \times I_O)}{\PI }\)

IDC = \(\frac {(2 \times 0.095)}{3.14}\)

IDC = 0.060 A.

The CORRECT choice is (a) β=\(\FRAC {\ALPHA }{1- \alpha}\)

To explain: IE=IB+IC

\(\frac {I_E}{I_C} =\frac {I_B}{I_C}\) + 1

\(\frac {1}{\alpha }=\frac {1}{\BETA }\) + 1

α = \(\frac {\beta }{1 + \beta}\)

Therefore, β=\(\frac {\alpha }{1- \alpha}\)

The correct option is (c) Emitter

Best explanation: Emitter is the section or REGION on one side of the transistor that supplies charge carriers. It is heavily doped and is ALWAYS kept FORWARD biased with RESPECT to the base so that it can SUPPLY a large number of charge carriers to the base.

Correct ANSWER is (C) Semiconductor

The explanation: A transistor is a semiconductor DEVICE. Transistors can work either as an amplifier or as a switch. It is USED to amplify or switch electronic signals. A transistor is a solid-state device MADE up of silicon and germanium.

The correct choice is (c) An amplifier with POSITIVE FEEDBACK

Easy explanation: An oscillator is CONSIDERED as an amplifier with positive feedback. It converts direct current from a power SUPPLY to an alternating current signal. It produces an alternating WAVEFORM without any input.

Correct OPTION is (c) Rectifier

The explanation: Semiconductor DIODE can be used as a rectifier. The function of a rectifier is that it converts an alternating CURRENT into direct current by allowing the current to PASS through in one direction.

The correct choice is (c) ICs are SMALL in SIZE and weight

The BEST I can explain: ICs are both small in size as well as in weight. As the fabrication process is used for the integration of ACTIVE and passive components on a silicon INTEGRATED circuit, the IC becomes a lot smaller. Also, due to its small size, the weight of the IC reduces, when compared to a discrete circuit.

The correct choice is (a) Logic gates have one or more input signals and only one output signal

Best EXPLANATION: Logic gates are the basic BUILDING blocks of any digital SYSTEM. A digital circuit with one or more input signals but only one output signal is KNOWN as a logic gate. All the other STATEMENTS are not valid.

The correct answer is (b) 600

For explanation: An INTEGRATED circuit (IC) is an assembly of electronic COMPONENTS, FABRICATED as a single unit, in which miniaturized active DEVICES and passive devices and their interconnections are BUILT upon a thin substrate of semiconductor material. There are about 600 different types of Integrated circuits.

Right answer is (B) False

The explanation is: No, this statement is false. FORWARD biasing of p-n junction diode offers low resistance and not high resistance. In the case of IDEAL p-n junction DIODES, the resistance is ZERO.

Correct choice is (b) 0.107 mA

The explanation: The expression for CURRENT gain is GIVEN as:

β=\(\FRAC {I_C}{I_B}\)

IC=50IB

Since, IE=IB+IC ➔ IE=IB+50IB

IE=51IB

IB=\(\frac {I_E}{51}=\frac {5.5}{51}\)=0.107 mA

Correct choice is (d) p-type semiconductor

Best explanation: INDIUM IMPURITY in germanium PRODUCES p-type semiconductors. A trivalent impurity added to germanium produces a p-type semiconductor. Trivalent IMPURITIES such as boron, indium, and gallium are CALLED acceptor impurity.

Right choice is (c) High temperature

Easiest explanation: A PURE semiconductor BEHAVES SLIGHTLY as a CONDUCTOR at high temperatures. Their resistivity increase as temperature INCREASES. Therefore, at high temperatures, semiconductors slightly act as a conductor.

Correct choice is (C) 3

Explanation: The LOGIC gates are CONSIDERED to be the BUILDING blocks of a digital system. Each logic gate FOLLOWS a certain logical relationship between input and output voltage. There are 3 basic logic gates, namely, OR gate, AND gate, and NOT gate.

Correct choice is (c) Photodiode

For EXPLANATION I would say: A photodiode is a semiconductor device, which converts light ENERGY to electric energy. It is a special type p-n junction diode fabricated with a transparent window to allow light to FALL on the diode. Photodiodes are OPERATED in reverse BIAS.

Right choice is (b) 1.21

Best EXPLANATION: For a half-wave RECTIFIER,

Irms=\(\FRAC {I_m}{2}\); IDC=\(\frac {I_m}{\pi }\)

r = \(\sqrt {\frac {(\frac {I_m}{2} )^2}{(\frac {I_m}{\pi } )^2} – 1}\)

r=1.21

The correct ANSWER is (b) Drift in REVERSE bias and diffusion in forward bias

The best explanation: Drift CURRENT flows from n-side to p-side while diffusion current flows from p-side to n-side. In forward BIASING, diffusion current is more than the drift current and in reverse biasing, drift current is more than the diffusion current.

Right answer is (C) Rectifier

Explanation: Diode is used as a rectifier. A rectifier diode allows CURRENT to pass in only one DIRECTION. A rectifier will be able to convert ALTERNATING current into direct current.

Correct choice is (c) Neutral

To elaborate: Semiconductors MAINTAIN their ELECTRICAL NEUTRALITY even after doping. This is achieved by adding an impurity to a PURE SEMICONDUCTOR in order to obtain an n-type semiconductor.

Right choice is (b) We need two NOT gates OBTAINED from NAND gates and one NAND gate

The EXPLANATION: We need OR gate (Y = A + B) from NAND gate (Y = not (A.B))

Y = not (not (A.B))

Y = not (not (A)) + not (not (B))[USING the Boolean identify ➔ not (A.B) = not (A) + not (B)]

So, Y = A + B[Since not (not (A)) = A and not (not (B)) = B]

THEREFORE, to OBTAIN an OR gate from a NAND gate, we need two NOT gates obtained from NAND gates and one NAND gate.

The CORRECT answer is (a) INSULATOR

Explanation: At the absolute zero temperature, an INTRINSIC semiconductor BEHAVES like an insulator. It is an undoped semiconductor. An intrinsic semiconductor at absolute zero temperature has ELECTRONS only in the valence band.

Right option is (d) Number of charge carriers

The best explanation: In an n-p-n transistor, as the BASE is very thin and lightly doped, a very few electrons from the emitter combine with the holes of the base, GIVING rise to base current and the electrons FINALLY collected by the positive terminal of the battery gives rise to collector current. This base current is a small fraction of collector current DEPENDING on the shape of a transistor, thickness of the base, doping levels, and bias VOLTAGE.

Right ANSWER is (C) Capacitor

The best I can explain: CAPACITORS are not easy to fabricate on an Integrated Circuit. In fact, they are the most difficult ones to fabricate. This is because capacitors require a lot of attributes such as electromagnetic compatibility, microfabrication techniques, NEW magnetic materials, ETC. and to integrate them, it costs a lot. Therefore, fabricating capacitors is a challenging task.

Right option is (a) Insulating component

To explain I would say: SiO2 acts as a diffusion mask permitting selective diffusions into the silicon wafer through the window ETCHED into oxide. In other words, it is USED for creating a PROTECTIVE SiO2 layer on the wafer surface of the IC. Therefore, SiO2 acts as an insulating component for INTEGRATED CIRCUITS.

Right option is (a) LED

Easy explanation: A light-emitting DIODE (LED) converts electric energy into light energy. A LED is a heavily doped p-n junction which under FORWARD bias emits spontaneous radiation. The semiconductor used for the FABRICATION of visible LEDs must at least have a bandgap of 1.8 EV.

Correct option is (b) Collector

The best I can EXPLAIN: The collector is the section on the other side of the transistor that collects the charge CARRIERS supplied by the emitter. It is moderately doped but large in size and is always kept in reverse bias with respect to the BASE.

Right ANSWER is (a) 849 V

Easy explanation: GIVEN: ERMS = 300 V

The required equation is ➔ P.I.V. = 2 × E0 or P.I.V. = 2√2 × Erms

P.I.V. = 2√2 × 300 V

P.I.V. = 848.52 V ≈ 849 V.

Right answer is (c) 2

For explanation I would SAY: Rectifier is a device that does the PROCESS of rectification. This means that RECTIFIERS straighten the DIRECTION of the CURRENT flowing through it. There are mainly 2 types of rectifiers, namely, full-wave rectifiers and half-wave rectifiers.

Right CHOICE is (b) False

For explanation: No, this is a false statement. Forward biasing of p-n junction offers LOW resistance. In the case of an IDEAL p-n junction, the resistance OFFERED is zero. So, forward biasing does not offer any resistance.

Correct ANSWER is (C) p-type extrinsic semiconductors

Best explanation: HOLES are the majority charge carriers in p-type extrinsic semiconductors. Trivalent impurities such as BORON, indium, and gallium are called acceptor impurity. Also, in p-type semiconductors, ELECTRONS are the minority charge carriers.

The correct answer is (a) Phosphorous

Best EXPLANATION: As phosphorous is pentavalent, it produces n-type SEMICONDUCTOR when added to silicon. They are called donor impurities. By ADDING PHOSPHORUS, extra VALENCE electrons are added that become unbonded from individual atoms.

The correct option is (b) Decreases exponentially with the increasing BANDGAP

Easiest explanation: At a finite temperature, the probability of jumping an ELECTRON from the valence BAND to the conduction band decreases exponentially with the increasing bandgap (Eg). The other OPTIONS are not valid.

Right answer is (a) Intrinsic semiconductors

Best EXPLANATION: In intrinsic semiconductors, the holes are CHARGE carriers.

For intrinsic semiconductors, the EXPRESSION is GIVEN as:

NH = ne.

Correct option is (a) True

The best explanation: YES, this is a true statement. The RIPPLE frequency is doubled in a full-wave RECTIFIER because we have to rectify both the POSITIVE and negative sides of the waveform. For EXAMPLE, if the input frequency is 50 Hz, then the ripple frequency of a full-wave rectifier is 100 Hz.

Correct OPTION is (d) Rectifier

Explanation: A JUNCTION diode can be used as a rectifier. The rectifier converts ALTERNATING current into direct current. During the positive half cycle, the diode is forward BIASED and allows electric current through it.

The correct OPTION is (b) Pauli’s exclusion principle

The EXPLANATION: The electronic configuration of ATOMS and consequently their manifestation of the band structure of solids can be WELL explained based on Pauli’s exclusion principle.

Right answer is (b) 10 W

The best I can explain: The maximum power RATING possible for a microcircuit is 10 Watts. INTEGRATED Circuits can’t be repaired because the individual components INSIDE the IC are too SMALL. As a result, the facility rating for many of the IC’s doesn’t exceed quite 10 watts. It’s impossible to manufacture high power IC’s and this is often one among the most important disadvantages of Integrated Circuits.

The correct option is (c) 0.097 A

The EXPLANATION: The REQUIRED EQUATION is as follows:

Ipeak=Irms × √2=\(\frac {V_{rms} \times \sqrt {2}}{R_L+2r_p}\)

Ipeak=\(\frac {360 \times \sqrt {2}}{5000 + 200}\)

Ipeak=\(\frac {360 \times 1.414}{5200}\)

Ipeak=0.097 A

Correct CHOICE is (b) NOT gate

Explanation: The NOT gate is the SIMPLEST of all logic gates. It has only ONE input and one output SIGNAL. NOT gate is ALSO called as the inverter because t inverts the input signal. All the other gates can have one or more input signals.

The correct ANSWER is (a) Convert ac voltage to dc voltage

The best explanation: A rectifier is based on the FACT that a FORWARD BIAS p-n junction conducts and a reverse bias p-n junction does not conduct electricity. The rectifier is used to convert alternating CURRENT voltage (ac) to direct current voltage (dc).

The CORRECT ANSWER is (c) 76

The BEST I can explain: Power gain is defined as the ratio of OUTPUT power to input power. It can also be determined as the product of current gain and voltage gain.

Given: α = 0.80, voltage gain (AV) = 95

The required equation ➔ AP = α × AV

AP=0.80×95

AP=76

The correct answer is (c) The MAJORITY carriers in n-type semiconductors are holes

To explain: The majority CHARGE carriers in n-type semiconductors are electrons, not holes. It is MADE by adding an impurity to a pure semiconductor such as SILICON or germanium. All the other statements are true.

The CORRECT choice is (c) COPPER STRIP decreases and that of germanium increases

To explain I would say: With the decrease of temperature, the resistance of copper, which is a metallic conductor, will decrease, whereas the resistance of germanium, which is a semiconductor will increase.