BEL Trainee Engineer Electrical Mock Test - 6 - Electrical Engineering (EE) MCQ

Concept:

Voltage regulation of the transmission line is defined as the ratio of the difference between sending and receiving end voltage to receiving end voltage of a transmission line between conditions of no-load and full load.

It can be expressed in percentage as

Sending end voltage for the transmission line is given as,

V_S =AV_r + BI_r

Under no-load condition, Ir = 0

Calculation:

Voltage at sending-end,

V_s = AV_R + BI_R

At no-load, I_R = 0

From the given data,

V_RF = 220 kV

From the above concept,

The common-emitter current gain is the ratio of the value of the transistor's collector current to the value of the transistor's base current in a transistor.

Note:

The common base DC current gain is a ratio of the value of the transistor's collector current to the value of the transistor's emitter current.

Since for a transistor Ie = Ib + Ic

α can now be written as:

Dividing both the numerator and denominator by Ib, we get:

Since

Also,

Important Point

Important Differences between different transistor configuration is as shown:

Most of the industrial loads can be classified into the following 4 general categories:

• Constant torque type load
• Torque proportional to speed (generator type load)
• Torque proportional to the square of speed (fan type load)
• Torque inversely proportional to speed (constant power type load)

Constant torque type load:

• Separately excited dc generators connected to a constant resistance load, eddy current brakes have speed-torque characteristics given by T = KW

Torque proportional to the square of speed (Fan type load):

• The torque speed curve of a load is a plot showing its torque requirement on the y-axis versus the speed on the x-axis.
• It’s the torque requirement of the load from zero speed to full speed.
• It’s application/load specific and varies with different load types.
• Load like centrifugal pumps and fan follows quadratic speed torque curve, where torque varies square times the speed.

Torque inversely proportional to speed:

• Load power remains constant in this type of load
• Lather, boring machine, milling machines, steel mill coiler, and electric traction load have this type of torque-speed characteristic.

Metal Drawing load:

• Metal drawing is a manufacturing process to do bulk deformation in metal work is worked upon to reduce its cross-sectional area.
• The bulk deformation signifies the massive changes in shape and a significant amount of deformation has been done.

Concept:

Star - delta starting:

• This method is applicable to start the induction motor whose stator windings are designed to operate with delta under running conditions.
• In the starting position, the current supply to the stator windings is connected in star (Y) for starting.
• In the running position, the current supply is reconnected to the windings in delta (∆) once the motor has gained speed.

Delta starting

Ist(phase) = V1 / Z01

Ist(line) = √3 Ist(phase) = √3 V1 / Z01

Star connected starting

Ist(line) = Ist(phase)

Ist(phase) = V1 / √3 Z01

The ratio of currents of star connection and delta connection:

The starting current with star starting is just 1/3rd when compared to direct delta starting. Therefore starting current is reduced.

The ratio of starting torque to full load torque of star-delta starter:

Starting torque also reduces to 1/3rd when compared to direct online starting.

When we connect the star-connected motor into a delta connection mode, the effective per phase voltage is increased to 1.732 times hence to maintain the torque and the speed it will draw 1/1.732 times the current.

Calculation:

⇒ (5 / I_st(delta)) = 1 / 3

⇒ I_st (delta) = 15 A

• Light-activated SCR or (LASCR) or a Photo SCR is just an ordinary SCR except that it can also be light-triggered.
• LASCR is a semiconductor device that turns ON when it is exposed to light.
• The LASCR is a type of thyristor which is triggered by photons present in the light rays.
• It is a three-terminal device, consists of cathode, anode and gate terminal.
• The gate terminal is used when the electrical triggering is supplied to the LASCR.
• The advantage of using light triggering for the thyristor is the prevention of electrical noise disturbances. Thus, LASCR is considered to be one of the best devices.

• LASCR works on the principle of photoconduction that is conduction due to photon striking the semiconductor surface.
• LASCR is basically a thyristor; it is made up of semiconductor material.
• The light rays falling on the device are focused at one place to intensify it.
• The more the intensity of light, the more will be the current through the LASCR.
• The primary function of a LASCR is to control electric power and current by acting as a switch.
• It is used as a rectifier because it can switch rapidly from a state of conducting current to a state of non-conduction.
• LASCR is used in a wide range of electric circuits.

Applications of the Light Activated SCR:

• Low Power Applications: The Light activated SCR is generally used for the application which requires low power to operate. This is because the power generated by SCR is low in magnitude.
• Motor Control: The Light Activated SCR finds applications in the working of Motor Control.
• Computer Applications: Components used in the computer system also require LASCR for meeting power requirements.
• Optical light Controls: The optical light control use the principle of photoconduction for generating the control signals. Therefore, the LASCR finds extensive application in Optical light control.

• Solid State Relay: In solid-state relays, two LASCR are connected in reverse parallel so that they can generate power in both the half cycle of AC.

Laws of Boolean Algebra:

Application:

Concept:

The inductance of a coil is given by,

μ₀ is magnetic permeability of free space

μ_r is relative permeability

N is number if turns

A is cross-sectional area

l is length

Calculation:

Given that, the number of turns of the coil is doubled

Length is halved

The cross-sectional area of the core remains constant

So, new inductance

For the addition of two hexadecimal numbers, there are two methods:

• In the 1^st method, we first convert the hexadecimal number to decimal then add both numbers. After that, we convert that decimal number to hexadecimal number. But it is a time-consuming method and also calculations become bulky.
• In the 2^nd method, we directly add both hexadecimal numbers as shown below

Concept:

Final value theorem:

It states that:

Conditions:

1. It is valid only for causal systems.

2. Pole of (1 – z-1) X(z) must lie inside the unit circle.

Calculation:

The final value theorem for z-transform is:

= 1/4 × 1 × 2 × 2 = 1

Given the circuit diagram:

To find Thevenin’s resistance, there is a need to suppress all independent sources with their internal resistance

Now, the circuit becomes

Now, introduce a current source of 1A between terminals A and B

Apply nodal analysis at node V_AB

⇒ 4 V_AB + V_AB = 1000

⇒ V_AB = 200 V

Now Thevenin's resistance

R_th = (V_AB / 1 A) = 200 Ω = 0.2 kΩ

Therefore, the Thevenin’s resistance across terminals A and B is 0.2 kΩ

Concept:

Time-domain specification (or) transient response parameters:

Delay time (td): It is the time taken by the response to change from 0 to 50% of its final or steady-state value.

Rise time (t­r): It is the time taken by the response to reach from 0% to 100% Generally 10% to 9% for overdamped and 5% to 95% for the critically damped system is defined.

Peak Time (tp): It is the time taken by the response to reach the maximum value.

Maximum (or) Peak overshoot (Mp): It is the maximum error at the O/P

If the magnitude of the input is doubled, then the steady-state value doubles, therefore Mp doubles, but % Mp, tr, tp remains constant.

Settling time (Ts): It is the time taken by the response to reach ± 2% tolerance band as shown in the fig above.

for a 5% tolerance band.

for 2% tolerance band

If ξ increases, rise time, peak time increases and peak overshoot decreases.

Calculation:

Characteristic equation: 1 + G(s)H(s) = 0

⇒ s² + 5s + 25 = 0

By comparing with the standard second order characteristic equation

ω_n = 5 rad/sec

ζ = 0.5

Damping ratio (ζ) = 0.5

Natural frequency (ωn) = 5 rad/sec

Settling time,

Peak time,

We can say that ,
Use structure “subject + auxiliary + past participle + by + object ”
The above given sentence is given in Passive Voice :-
I was told by somebody that there had been an explosion in the Town Hall.
Hence , required answer will be option D .

As we know that ,
Rampant is widespread, something that can’t be controlled or kept in limits, furious is angry and restrained is controlled, kept in limits.
Hence , Restrained is opposite word of Rampant . 

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."

As we know that ,
Sublime is magnificent and great, base is anything low, ordinary, concise means short or compact, partial is not complete, and Insist is to make a request.
Therefore , required word is base . 

One word substitution is Stickler.

Disciplinarian: A person who believes in or practises firm discipline.

Stickler: A person who insists on a certain quality or type of behaviour.

Instantaneous: Occurring or done instantly.

Boaster: A very boastful and talkative person.

• A: Refers to a printed chart.


• B: Indicates a chart that is filled in by an analyst while formatting a report.


• C: Describes a chart that is prepared by users.


• D: States that the chart is printed by a computer.

• Step 1: Open the worksheet you want to select.


• Step 2: Locate the rectangle box on the upper left corner where column headings and row headings meet.


• Step 3: Click on the rectangle box.

The quickest way to select the entire worksheet is to click on the rectangle box on the upper left corner where column headings and row headings meet. This box is known as the "Select All" box and it allows you to select the entire worksheet in just one click.

This method is faster than other options because it saves you the time and effort of manually selecting each column or row. By clicking on the "Select All" box, you instantly select the entire worksheet including all columns, rows, and cells.

Using this method, you can quickly perform tasks such as formatting, copying, or deleting the entire worksheet without having to individually select each element. It is a time-saving technique that is particularly useful when working with large worksheets.

Therefore, the correct answer is Option D: Click on the rectangle box on the upper left corner where column headings and row headings meet.

Logic: We have to make a family tree as per the above conditions.

Consider the below symbols.

The family tree for the given problem is as follows:

In the question, Her father is the only son of my father means woman's father and the man's father's only son is the same person means he is talking about himself. 

As the man is the father of that woman.

Therefore, the correct answer should be "Option 1: Father".  

Preparing the family tree using the following symbol:

According to the given information,

Hence, Q is the grandmother of S.

The numeric value of the letters (considering A to be 1 and Z to be 26) is added and simplified to obtain a single digit.

For RAM, the numeric value of R, A and M is 18, 1 and 13 respectively. Their sum is 32, Now 32 is further simplified to obtain a single digit by adding 3 and 2, which gives us 5 as the final value.
Similarly for GUI, the numeric value of G,U and I is 7, 21 and 9 respectively. Their sum is 37, which is simplified as 3 + 7 = 10 => 1 + 0 = 1.
Similar process will be done to obtain the code for SAP, the numeric value of S, A and P is 19, 1 and 16 respectively. Their sum is 36, which is simplified as 3 + 6 = 9.
So, the code for SAP is 9.
Hence option (B) is correct.

The logic that follows here is 

1) D is sitting to the immediate left of A.

2) C is sitting to the immediate right of B.

3) B is not sitting adjacent to A.

The final seating arrangement will be

Second to the right of D is 'E'.

Hence, the correct answer is E.

By using the symbols in the table given below, we can draw the following family tree:

We do not know the gender of Shanti. 
Clearly, Shaurya is the cousin of Karan.
Hence, ‘Cousin’ is the correct answer.

From the common explanation, we get (P, H) sits at the extreme end of the row.
Hence, Option D is correct.
Final Arrangement:

Common Explanation:
References:
Only two boys sit to the left of J.
Eight boys sit between R and J.
Only three boys sit between R and M.
Inferences:
From the above references, we get two different cases:

References:
P sits fourth to the right of R.
O sits third to the left of M.
Inferences:
So, from this case 2 will be eliminated as P sits fourth to the right of R.

References:
Only three boys sit between O and H.
T sits third to the right of M.
V sits fourth to the right of O.
More than 12 boys sit between P and H.
More than seven boys sit between P and J.
Inferences:
From the above reference, we get the final arrangement: