MPPGCL JE Electronics Mock Test - 6 - Electronics and Communication Engineering (ECE) MCQ

Pentavalent impurities:

Impurity atoms with 5 valence electrons produce n-type semiconductors by contributing an extra electron.

This is as explained in the figure:

The energy band diagram for an  n-type semiconductor will be as shown:

Trivalent Impurities:

Impurity atoms with 3 valence electrons produce p-type semiconductors by producing a "hole" or an electron deficiency.

The correct answer is option 3.

Concept:

The given circuit is,

The resultant expression is,

Y= (A+B). C.D.E   here (.) is and operation and (+) is or operation

Y=(A+B).CDE

This is also written as,

Y=C(A+B)DE

Hence the correct answer is C(A+B)DE.

The bandgap energy (E_g) in the minimum energy required to break a covalent bond and thus, generates an electron-hole pair.

The energy gap is the shortest distance between the valence layer and the conduction layer.

The Energy required for a photon to create an e-h pair is a little bit larger than band-gap in the case of indirect band-gap semiconductor

Comparison of different semiconductor bandgap is as shown:

​Important Point

i.e. Energy Gap decreases with the temperature increase

Mathematically, this relation is given by:

E_G(T) = (E_G0 – β₀T) eV

E_G0 – Bandgap energy at OK

β₀ – material constant eV/°K

Since at t = 0, the switch is closed.

So at t > 0, the circuit will be.

Redrawing above circuit in s-domain – 

i(t) = 10 u(t) Amp

NOTE:

Since the switch is closed t ≥ 0

So 10 V will work only after t ≥ 0 that’s why we take voltage source as 10 u(t). In Laplace or s-domain  

Concept:

A single sideband (SSB) AM Signal is represented as

m̂(t) → represent Hilbert transform of message signal

(-) → sign represent USB

(+) → sign represent LSB

Hilbert transform:

It is a specific Linear operator that takes a function u(t) of a real variable and produces another function of real variable H(u)(t)

→ It imparts a phase shift of ± 90° (π/2 radians) to every frequency component of a function.

Explanation:

From the given Block diagram.

I₁ = (Am sin ω_mt)(Ac cos ω_ct)

I₂ = (Am cos ω_mt)(Ac cos ω_ct)

V_out = I₁ + I₃

From I₁  

Then

Option (A) correct choice.

Short trick:

Observe the V_out in block diagram i.e. V_out = I₁ + I₃

But in I₃ there is –π/2 phase change so the SSB becomes in the Form of

S(t) = m(t) cos ω_ct – m̂(t) sin ω_ct

And (-) sign represent USB only.

So the student can tick the correct answer.

Cleavage plane:

• When a crystal is break or fracture easily along a definite plane then this plane is called cleavage plane.
• It is used to identity mineral and its quality.
• It forms generally in a lower energy crystal structure.
• In silicon, most preferred cleavage plane is < 111 >

• A point-to-point connection provides a dedicated link between two devices
• In mesh, star and ring topologies are a point-to-point connection
• In a star topology, each device needs only one link and one I/O port to connect it to any number of other devices
• In a ring topology, each device has a dedicated point-to-point connection with only the two devices on either side of it; Each device is connected to its corresponding repeater
• In a mesh topology, every device has a dedicated point-to-point link to every other device
• A multipoint connection is one in which more than two specific devices share a single link
• In Bus Topology, one long cable acts as a backbone to link all the devices in a network

Potential field ϕ = 2xy² – 3y²z

Now, electric field intensity at (0, 1, 0) is,

E = -∇ϕ 

At the given point (0, 1, 0)

⇒ x = 0, y = 1, z = 0

E = (-2x̂ + 3ẑ) V/m

ASK, PSK and FSK are signaling schemes used to transmit binary sequences through free space.

In these schemes, bit-by-bit transmission through free space occurs.

In ASK (Amplitude shift keying) binary ‘1’ is represented with the presence of a carrier and binary ‘0’ is represented with the absence of a carrier:

For binary ‘1’ → S₁ (t) = Acos 2π f_ct

For binary ‘0’ → S₂ (t) = 0

The Constellation Diagram Representation is as shown:

Concept:

A Zener diode is a silicon semiconductor device that permits current to flow in either a forward or reverse direction. The diode consists of a special, heavily doped p-n junction, designed to conduct in the reverse direction when a certain specified voltage is reached.

Voltage Vz: The Zener voltage refers to the reverse breakdown voltage.

Current Iz (max.): Maximum current at the rated Zener voltage Vz.

Current Iz (min.): Minimum current required for the diode to break down.

Calculation:

Given;

V_z = 10 V

Open circuit the Zener diode to calculate the voltage appearing across the diode.

V_x = 16 × 4.2/(4.2+1) = 12.92 V

As, V_x > V_z → Zener diode will be in the breakdown region.

V_L = V_Z = 10 V

The correct answer is Broadcast.

Key Points

• IP stands for Internet Protocol is a unique address that identifies a system or any device that works on the internet.
• It sets certain rules for transferring data over the internet.
• There are various types of IP addresses like Public IP address, Private IP addresses, Dynamic and Static IP addresses etc.
• Based on the number of bits, there are two versions of IP address: IPv4 and IPv6. 
• IPv6 is a 128-bit hexadecimal address separated into 8 groups of 16 bits by a colon.
• Here, the first 48 bits are network IDs, the next 16 bits are subnet IDs, and the last 64 are client IDs.
     

• There are three types of IPv6 transmission. They are Unicast, Anycast and Multicast. Hence option 2 is correct.
• A Unicast type uniquely identifies a single interface on an IPv6 device. A packet sent to a unicast address destination travels from the source host to the destination host.
• Anycast address identifies the set of interfaces at different locations in such a way that a packet sent to an anycast address will be delivered to a member of the set.
• Multicast addresses identify a group of interfaces such that a packet sent to a multicast address is delivered to all the interfaces in the group.

Additional Information

• IPv4 is a 32-bit address, first deployed by ARPANET (Advanced Research Projects Agency Networks).
• IPv4 transmission types are Unicast, Multicast and Broadcast.
• Broadcast in IPv4 is a network address that is used to transmit to all the devices connected to multiple networks. The message sent to a broadcast is received by all hosts.

Finite Impulse Response (FIR) filter

• In signal processing, a finite impulse response (FIR) filter is a filter whose impulse response is of finite duration because it settles to zero in finite time.
• FIR filters can be discrete-time or continuous-time, and digital or analog.
• The impulse response of an Nth-order discrete-time FIR filter has exactly N+1 samples.
• For a linear-phase filter, group delay and phase delay are of the same value. So linear-phase filters are also called Constant Time Delay Filters.
• An FIR filter is a linear phase if its coefficients are symmetrical or anti-symmetrical around the center coefficient.

Excess-3 Addition:

Step 1: We have to convert the numbers (which are to be added) into excess-3 by adding 0011 with each of the four-bit groups.

Step 2: Now the numbers are added using the basic laws of binary addition.

Step 3: Now, whichever of the four-bit groups have produced a carry, we have to add 0011 with them and subtract 0011 from the groups which have not produced a carry during the addition.

Step 4: The result which we have obtained after this operation is in Excess-3 form

Ex: (1)₁₀ + (4)₁₀ = (5)₁₀

XS – 3:    0100 + 0111 = 1011 = (11)₁₀

But we are supposed to get 1000, as XS-3 for (5)₁₀ is 1000.

So, we need to subtract 3 from the result

Ex: (6)₁₀ + (7)₁₀ = (13)₁₀

In XS-33: 1001 + 1010 = 10011

But we are supposed to get 0100 0110

So we need to add 011 to the result.

4-bit XS-3 Adder:

If C₄ = 1, then add three to the result (S₃ S₂ S₁ S₀)

If C₄ = 0, the subtract three (0011) from the result i.e. 2’s complement of three (1101) is added.

∴ Two 4-bit parallel adders are needed.

Solution

Concept

The 2nd order transfer function for the underdamped system for a step input is given by  , where

• ζ is the damping ratio
• ω_n is the natural oscillating frequency
• k is the open-loop gain

Calculation 

Given,

The open-loop transfer function 

The closed-loop transfer will be 

Now compare it with the standard formula 

We have, 2ζω_n =3 and ω_n²=k

Also given in the question ζ =0.5

⇒ω_n= 3

⇒k=9

Therefore the correct value of k=3

Hence the correct option is 4

Wien-Bridge Oscillator:

• One of the simplest sine wave oscillators which use an RC network in place of the conventional LC tuned tank circuit to produce a sinusoidal output waveform is called a Wien Bridge Oscillator.
• A Wien-Bridge Oscillator is a type of phase-shift oscillator which is based upon a Wien-Bridge network shown below in figure (a) comprising four arms connected in a bridge fashion.
• Here two arms are purely resistive while the other two arms are a combination of resistors and capacitors.

• In particular, one arm has a resistor and capacitor connected in series (R₁ and C₁) while the other has them in parallel (R₂ and C₂).
• This indicates that these two arms of the network behave identically to that of a high pass filter or low pass filter, the behavior of the circuit shown in Figure (b).
• In this circuit, at high frequencies, the reactance of the capacitors C₁ and C₂ will be much less due to which the voltage V₀ will become zero as R₂ will be shorted.
• Next, at low frequencies, the reactance of the capacitors C₁ and C₂ will become very high.
• However, even in this case, the output voltage V₀ will remain at zero only, as the capacitor C₁ would be acting as an open circuit.
• This kind of behavior exhibited by the Wien-Bridge network makes it a lead-lag circuit in the case of low and high frequencies, respectively.

Wien bridge oscillator frequency calculation:

• In between these two high and low frequencies, there exists a particular frequency at which the values of the resistance and the capacitive reactance will become equal to each other, producing the maximum output voltage.
• This frequency is referred to as the resonant frequency (f_r).
• The resonant frequency for a Wein Bridge Oscillator is calculated using the following formula given below

If R₁ = R₂ = R and C₁ = C₂ = C

then 

• The Wien Bridge oscillator is a two-stage RC coupled amplifier circuit that has good stability at its resonant frequency and low distortion.
• It is very easy to tune making it a popular circuit as an audio frequency oscillator but the phase shift of the output signal is considerably different from the previous phase shift RC Oscillator.
• ​The Wien Bridge Oscillator uses a feedback circuit consisting of a series RC circuit connected with a parallel RC of the same component values producing a phase delay or phase advance circuit depending upon the frequency. 
• At the resonant frequency (ƒr) the phase shift is 0o in the Wien Bridge oscillator.

Additional Information
Schering bridge:

• This bridge is used to measure to the capacitance of the capacitor, dissipation factor and measurement of relative permittivity.
• The circuit diagram of the Schering bridge is shown below:

Hay’s bridge:

• The bridge gives a very simple expression for the calculation of unknown inductors of high value. 
• The circuit diagram of Hay's bridge is shown below:

Maxwell’s bridge:

• The bridge used for the measurement of self-inductance of the circuit is known as the Maxwell bridge. It is the advanced form of the Wheatstone bridge.
• The Maxwell bridge works on the principle of comparison, i.e., the value of unknown inductance is determined by comparing it with the known value or standard value.

• The circuit diagram of Maxwell's inductance bridge is shown below:

Waveguides are used to direct and propagate Electromagnetic waves from one point to another. They are generally used to transmit high frequency waves such as Microwaves, Radio waves, Infrared waves etc.

The signals with high frequencies are allowed to propagate through the waveguide whereas the signals below the frequency will face a high reflection.

Waveguides are classified into two types:

1. Metal waveguides: Metal waveguides consists of enclosed conducting metal pipe and the wave guiding principle works on the total internal reflection.

2. Dielectric waveguides: These waveguides consists of dielectrics and the reflection from dielectric interfaces helps in the propagation of electromagnetic waves along the waveguide.

Metal waveguides are classified into two types:

1. Rectangular waveguides  2. Circular waveguides

A circular waveguide is a hollow metallic tube with circular cross section for propagating the electromagnetic waves by continuous reflections from the surfaces or walls of the guide.

A waveguide with a circular cross section is called as circular waveguide. It supports both Transverse electric (TE) and Transverse magnetic (TM) modes..

TM₀₁ mode is preferred to TE₀₁ as it requires a smaller diameter for the same cut-off wavelength.

The waveguides of circular cross section are used to transmit EM waves from one point to another.

The root values for the TM modes are:

  01 = 2.405 for TM01

  02 = 5.53 for TM02

  11 = 3.85 for TM11

  12 = 7.02 for TM12 

The dominant mode for a circular waveguide is defined as the lowest order mode having the lowest root value. 

The circular waveguides are perfectly symmetrical around the axis. Because of it's symmetrical nature, the dominant mode for TM waves in a circular waveguide is TM₀₁. The dominant mode TM₀₁ has the lowest root value of 2.405.

conclusion: option 2 is correct

In the above circuit, all the marked currents are flowing in the same direction and through the same branch.

∴  i_s = i₁ = i₂ = i₃ 

Option D is the only wrong statement.

Notes:

By KVL ∑V = 0

While applying KVL, the direction in which the loop is to be traced is not important. Following the sign-convention is most important which is shown in below circuit

We can write an equation by using KVL around this closed path as,

-I₁ R₁ + E₁ – I₂ R₂ – I₃ R₃ – I₄ R₄ + E₂ = 0 (Required KVL equation)

i.e. E₁ + E = I R₁ + I₂R₂ + I₃R₃ + I₄R₄

Channel Capacity Per Symbol C_s

The channel capacity per symbol of a discrete memoryless channel (DMC) is defined as:

Where,

I(X;Y) = H(x) – H(x|y)

H(x): Entropy of x

Where the maximization is over all possible input probability distribution {P(x_i)} on X. Note that the channel capacity C_s is a function of only the channel transition probabilities which define the channel.

Noiseless Channel:

A channel is called noiseless if it is both lossless and deterministic.

A noiseless channel has been shown in the figure below:

The channel matrix has only one element in each row and each column, and this element is unity. Note that the input and output alphabets are of the same size, that is m = n for the noiseless channel.

Since a noiseless channel is both lossless and deterministic, we have

I(X;Y) = H(X) = H(Y)

And the channel capacity per symbol is

C_s = log₂m = log₂n

Concept:

Lockout free condition: If a counter from an unused state enters one of the used states then the counter is called lock-out free. While taking any unused state as the initial state if the next state comes out to be a used state, the counter is said to be lockout free.

Synchronous counter: A counter in which all the flip-flops are triggered with the same clock pulse. In such counters, if the propagation delay of one flip-flop is tf, then the propagation delay for the whole counter will also be tf

Asynchronous counter: A counter in which all the flip flops are not triggered by the same clock pulse. In such counters, total propagation delay will be equal to the sum of propagation delay for all flip flops.

Calculation:

Given that, propagation delay of each flip-flop = 40 ns

Width of the strobe pulse = 20 ns

Total propagation delay = 40 × 4 + 20 = 180 ns

Maximum clock frequency 

CONCEPT:

• Potentiometer: The instrument designs for measuring the unknown voltage by comparing it with the known voltage, such type of instrument is known as the potentiometer.
• In other words, the potentiometer is the three-terminal device used for measuring the potential differences by manually varying the resistance. The known voltage is drawn by the cell or any other supply sources.

CHARACTERISTICS OF POTENTIOMETER

• The potentiometer is very accurate because it works on the comparing method rather than the deflection pointer method for determining the unknown voltages.
• It measures the null or balance point which does not require power for the measurement.
• The working of the potentiometer is free from the source resistance because no current flows through the potentiometer when it is balanced.

WORKING OF POTENTIOMETER

• The working principle of the potentiometer is explained through the circuit shown below.
• consider S is the switch used for connecting or disconnecting the galvanometer from the potentiometer. 
• The battery through the rheostat and slide wire supply the working current.
• The working current may vary by changing the setting of the rheostat.

• The method of findings the unknown voltage depends on the sliding position of the contact at which the galvanometer shows the zero deflection. 
• The Zero or null deflection of galvanometer shows that the potential of the unknown source E and the voltage drops E1 across the sliding wires are equal. Thus the potential of the unknown voltage drops across the ac portion of the sliding wire.
• The slide wire has the uniform cross-section and resistance across the entire length. As the resistance of the sliding wire is known, then it is easily controlled by adjusting the working current. 
• The process of equalising the working voltage drop is known as the standardization.

Explanation:

A galvanometer can be converted into a voltmeter by connecting a large resistance in series with it.

1st term = 34/2 +1 = 18
2nd term = 18/2 +1 = 10
3rd term = 10/2 +1 = 6
4th term = 6/2 + 1  = 4

Thus, the missing number is 5th term = 4/2 + 1 = 3

Let us first learn the meanings of the given words:

Reverberate (verb): be repeated several times.

Echo (verb): repeat (someone's words or opinions), typically to express agreement.

Resonate (verb): to produce or be filled with clear, continuing sound.

The idea here is to express that the end of FTX is a continuous topic of discussion, thus all the options are apt contextually and grammatically.

Hence, the correct answer is option C.

Belle of the ball: the most beautiful woman in a gathering.
The usage of the idiom in statement I is absolutely correct.
Make a beeline: to go straight for something.
The usage of the idiom in statement II is absolutely correct.
Break one’s neck: get through the hardest part of something.
The idiom is incorrectly used in the sentence and the correct idiom will be ‘do not have a clue’.
Not have a clue: to not know something.
Hence, the correct answer is option C. 

There are 8 triangles in the figure. By counting the individual triangles, we can see that there are 2 large triangles, 4 medium triangles, and 2 small triangles, making a total of 8 triangles.

For ensuring that there is just ways to function there should be proper guidelines and therefore mandated code of conduct.

A cabinet is an official government body consisting of high ranked officials of the state. The members of the cabinet are generally called Cabinet Ministers or Secretaries. It is the main body which is responsible for the day-to-day management of the government.

• The area between the Tropic of Cancer and the Tropic of Capricorn is known as the Torrid Zone.
• The mid-day Sun is exactly overhead at least once a year on all the latitudes in this area; hence, this area receives maximum amount of heat.

Following the common explanation, we get “Y sits near A”.
Hence, option C is correct.
Final Arrangement:

Common Explanation:
References:
1. Two people are sitting between A and Z.
2. C sits fourth to the right of Z.
3. The number of people sitting to the right of A is the same as the number of people sitting to the left of Z.
4. The number of people sitting between A and C is the same as the number of people sitting between X and C.
5. X is an immediate neighbour of D, who sits on one of the ends.
6. The number of people sitting between D and C is the same as the number of people sitting between C and Y.
7. At most 25 people are sitting in a row.
Inferences:
From reference 1, we get two possible cases.
From reference 7, case2 was eliminated.
Hence, Case 1 is the final arrangement.

The correct transformation of the sentence from active to passive voice is:

"You should not offer meat to vegetarians."

The transformed sentence in passive voice is: "Vegetarians should not be offered meat."

Therefore, the correct answer is option C: "Vegetarians should not be offered meat."