Full Test 4 - EKT EEE - AFCAT MCQ

The given matrix is 

 

The determinant is given as |A| = λ³ – 1               

If ⍴(A) is given as 2, then the determinant of A should be zero

⇒ |A| = 0 ⇒ λ³ – 1 = 0;

We get λ = 1  at which there are more than one 22 sub-matrices having non zero determinant

∴ value of λ is 1 for which rank of A is 2

Given that 
Squaring the above equation, we get 
Putting the values, the equation becomes 
Thus we get 
∴ a ⊥ b
∴ Angle between 

The given integral is of the beta function. Hence it can be written as

Here n = 4, therefore the integral becomes

L{a.cosat}
=a.L{.cosat}

We know that P(X∪Y)=P(X)+P(Y)−P(X∩Y)
Given that both X and Y are independent hence P(X∩Y)=P(X).P(Y)
So 0.8=P(X)+0.5−0.5×P(X)
0.3=0.5P(X)

Magnitude of resultant Forces F₁ and F₂ is:

F₁ and F₂ = P

The unit of thermal resistance is kelvin per watt. So the dimension for it will be [power]^-1[K]. The dimension will thus be [M^-1L^-2T³K].

RC is the time constant of a series resistance capacitance DC voltage circuit. The dimension of RC is same as that of time.

Color in soap bubble is due to phenomenon of thin film interference. There is a thin film like structure formed between the outer and inner surface of the bubble, which reflects a spectrum of beautiful colors from its surface.

The physical properties of electromagnetic waves can be determined from the spectroscopy experiment which detects the wavelengths of objects emitting these.

Greater the stiffness of the material, more is the speed. Speed of sound in metallic solid will be higher than in a gas or liquid. Hence the velocity of sound will be least in distilled water.

A line AB is parallel to both HP and VP. Its side view will be a point.

Or it can be viewed as:

ECL - Emitter Coupled Logic circuit uses differential pair of transistors biased by constant current source coupled to emitter.

Depending on the logic the current flows from one transistor or the other, the total current drawn by the circuit remains same regardless of logic.

Since the current is constant during switching , hence unlike in CMOS or TTL no noise spikes occur during switching.

Transformer coupled class B push pull amplifiers:

1. It suffers from cross over distortions

2. It eliminates even harmonic distortion

3. Its device ratings lower than class A power amplifiers

4. Theoretical efficiency is 78%

Op-Amp comparator circuit is used to compare the difference between voltage level of two inputs (inverting and non-inverting) and also determines which one is greater. It requires no feedback circuit.

Crystal Oscillator has two closely spaced resonant frequency. In crystal oscillator, series resonant frequency occurs when reactance of the capacitor is equal to the reactance of the inductor (low impedance). Parallel resonant frequency occurs when reactance of the capacitor C2 is equal to the reactance of RLC1 branch (High impedance).

To get the dual of the given expression change OR to AND operator and AND to OR operator.
A+[B+(AC)]+D=A[B(A+C)]D

(657)₈=(110101111)₂=(1AF)₁₆=1AFH

DAC has 10 bits, that means the total number of steps =2¹⁰−1=1023
Resolution = 

Full adder, full subtractor and half adder are combinational circuits.

JK flip flop and counter are sequential circuits.

Differential circulating current protection scheme or merz-price protection scheme is a popular method of alternator stator protection.

• Transformer cores are laminated in order to minimize eddy current loss.
• By providing laminations, the area of each part gets reduced and hence resistance will get very high which limits the eddy current to a minimum value and hence eddy current losses gets reduced
• The laminations provide small gaps between the plates. As it is easier for magnetic flux to flow through iron than air or coil, the stray flux or leakage flux that can cause core losses is minimized.

Apart from the armature core, the pole core and pole shoes are also laminated. They are made of thin laminations of annealed steel which are riveted together.

In an ideal transformer, there are no no-load losses and magnetic leakage losses. Rest other things can be used in practical transformers also.

In commutation, if reversal of current is completed during the short circuit time then the coil develops reactance voltage due to which sparking occurs at the brushes.

The value of Junction depletion capacitance is given by

Where A = Area of junction
W = width of Depletion region = 

P-i-N photodiodes contain layer of intrinsic semiconductor sandwiched between, P and N type semiconductors. The depletion region is contained entirely in the i-region.The thickness of intrinsic region can be adjusted to produce device with optimum sensitivity and frequency response.

Avalanche photo diodes arc reverse-biased p-n junction diodes that arc operated at voltages above breakdown voltage. They have higher power handling capacity.

When impurities are added to other wise perfect crystals of semiconductors additional energy levels are created. In P-type semiconductor accepted impurities have one covalent bond empty which will easily accept a free electron from valence band due to thermal or optical excitation. The energy level is closer to valence band in P-type semiconductor.

In an n-channel enhancement MOSFET, the drain current flows through the narrow channel of electrons produced in the p-type substrate due to applied minimum VGS known as the threshold voltage.

With the increase in the number of minority charge carriers in the substrate (in this case electrons) less gate-source voltage is needed to start drain-current. So to increase threshold voltage minority charge carriers need to be reduced, hence channel doping should be increased

Hence threshold voltage of an n-channel MOSFET can be increased by increasing the channel(substrate) doping concentration.

Sheet resistance is a measure of resistance of thin films that are nominally uniform in thickness. It is commonly used to characterize materials made by semiconductor doping, metal deposition, resistive paste printing, and glass coating.