Mixed Electromechanichal Questions part 1

Mixed Electromechanichal Questions  part 1

1. An electro-mechanical energy conversion device is one which converts _______

a) Electrical energy to mechanical energy only

b) Mechanical energy to electrical energy only

c) Electrical to mechanical and mechanical to electrical

d) None of the mentioned

PERPLEXITY

An electromechanical energy conversion device is a device that can convert electrical energy

into mechanical energy or mechanical energy into electrical energy

. Electromechanical energy conversion takes place through the medium of a magnetic field or an

electric field, but most practical converters use magnetic field as the coupling medium between

electrical and mechanical systems, this is because the electric storing capacity of the magnetic

field is much higher than that of the electric field

. The conversion of electrical energy into mechanical energy and vice-versa takes place through

the medium of an electric field or a magnetic field

. The total input energy in an electromechanical energy conversion device is equal to the sum of

three components: energy dissipated, energy stored, and energy transferred

. Examples of electromechanical energy conversion devices include electric generators and

electric motors

2. The primary and secondary of a transformer are ________ coupled but _______ connected.

a) electrically, also electrically

b) electrically, not magnetically

c) magnetically, also magnetically

d) magnetically, not electrically

PERPLEXITY

The primary and secondary of a transformer are magnetically coupled but electrically separated

. The primary and secondary windings of a transformer are interlinked magnetically by a

common magnetic core

. The transformer is an electrostatic device that transfers electrical energy from one

alternating-current circuit to another through the common magnetic core at the same frequency

. The coupling transformer is used to feed the output of the first stage to the input of the second

stage in a transformer-coupled amplifier circuit

. The high impedance primary of the transformer is connected to the high impedance collector

circuit in a transformer-coupled class A power amplifier

. The coil or inductor in which the source current is passed is called the primary winding, or

simply primary, and the coil or inductor in which the current is induced is called the secondary

winding, or simply secondary

___ 3. For a 4 pole three phase induction motor having synchronous speed of 1500 rpm is

operating at 1450rpm. The frequency of the induced emf in rotor is? a) 50 Hz b) 100 Hz c) 150

Hz d) 0 Hz

PERPLEXITY

The frequency of the induced emf in the rotor of a 4 pole three-phase induction motor having

synchronous speed of 1500 rpm and operating at 1450 rpm is 100 Hz

. The induced frequency can be calculated using the formula f = P(Ns-Nr)/2, where f is the

induced frequency, P is the number of poles, Ns is the synchronous speed, and Nr is the rotor

speed

. Substituting the given values, we get f = 4(1500-1450)/2 = 100 Hz

. Therefore, the answer is option (b) 100 Hz.

_ 4. Speed control is possible for _______ and not possible for __________

a) induction motor, synchronous motor

b) induction motor, differential motor

c) synchronous motor, synchronous-induction motor

d) dc motor, induction motor

PERPLEXITY

Speed control is possible for induction motors, but not possible for synchronous motors

. Induction motors can be controlled by using voltage control method, resistance control

method, frequency control method, and rotor resistance control method

. The speed regulation of an induction motor is defined as the change in the motor speed with

respect to the change in the load torque

. On the other hand, synchronous motors are constant speed motors that run at the synchronous

speed of the supply

. They are generally used for constant speed operation under no load conditions such as to

improve the power factor

. The synchronous speed of a synchronous motor depends on the frequency of the supply and

the number of poles of the rotor

. Changing the number of poles is not easy, so the frequency of the current fed to the

synchronous motor can be varied using solid-state devices to control the speed of the

synchronous motor

. Therefore, the answer is option (c) synchronous motor, synchronous-induction motor.

__ 5.Which of the following can be done using a synchronous motor but not by induction motor?

a) Power factor improvement and supply mechanical load

b) Supplying mechanical load

c) Power factor improvement

d) None of the mentioned

PERPLEXITY

Power factor improvement can be done using a synchronous motor but not by an induction

motor

. Synchronous motors are used as synchronous condensers for power factor improvement

. A synchronous condenser is a synchronous motor that is over-excited to generate reactive

power and improve the power factor of the system

. The synchronous motor runs at a constant speed and is connected to the power system

through a switch that allows it to be switched on or off as required

. On the other hand, induction motors are not used for power factor improvement as they do not

have the capability to generate reactive power

. Therefore, the answer is option (a) power factor improvement and supply mechanical load.

6.Inspite of heavy initial investments, dc motors are used due to _____________

a) flexibility and ease of controll

b) lower losses

c) improved power factor of the system

d) all of the mentioned

PERPLEXITY

DC motors are used due to their flexibility and ease of control, as well as their high starting

torque, quick starting and stopping, reversing, and variable speeds with voltage input

. They are also cheaper and easier to control than AC motors

. DC motors offer highly controllable speed, and changing the armature or field voltage can

achieve wide speed variation

. They have a high starting torque, making them perfect for use in applications that are designed

to move heavier loads

. DC motors develop full torque at low speed and across the full operating range from zero to

base speed, making them the best choice in certain applications

. They have no field coil in the stator, so the field coil space is saved, reducing the overall motor

size, which becomes a substantial benefit in some space-constrained applications

. DC motors are typically more efficient and make better use of their input energy than AC

motors

. They are available in several standard voltages and offer a wide range of speed control both

above and below the rated speeds

. In summary, DC motors are used due to their flexibility, ease of control, high starting torque, and

variable speeds with voltage input.

7. Hoists, cranes and battery powered vehicles use _________ motors in the locomotive.

a) dc shunt b) dc series

c) induction d) reluctance

PERPLEXITY

Hoists, cranes, and battery-powered vehicles use DC series motors in the locomotive

. Series DC motors are a group of self-excited DC motors in which the field coil is connected in

series to the armature winding and thus a higher current passes through it

. The series-wound DC motor develops its highest torque at low speed, making it often used in

traction applications such as electric locomotives and trams

. The series motor has very high starting torque and is commonly used for starting high inertia

loads, such as trains, elevators, or hoists

. The power of a series DC motor is the output energy provided by the motor

. The series wound DC motor is similar in almost all aspects to other DC motor types but has

some important unique properties

. In summary, DC series motors are used in hoists, cranes, and battery-powered vehicles in the

locomotive due to their high starting torque and suitability for starting high inertia loads.

8. If a self excited DC generator is failed to run, this refers to ________________

a) resistance is greater than critical resistance

b) field MMF, that it is not cumulative

c) zero residual voltage

d) any of the mentioned

PERPLEXITY

If a self-excited DC generator fails to run, it refers to any of the mentioned reasons below

Resistance is greater than critical resistance.

Field MMF, that it is not cumulative.

Zero residual voltage.

A self-excited DC generator is excited from its own armature terminals, and this method of

excitation is known as self-excitation

. If the field winding is connected such that the flux produced by the field current opposes the

residual flux, the generator fails to build up

. The generator may fail to build up if there is no residual magnetism, wrong field winding

connection, wrong direction of rotation, resistance of field-winding (Rf) greater than critical

resistance (Rc), or speed of rotation less than critical speed (Nc)

. The voltage build-up of the DC generator is given by the point of intersection of the

magnetization curve and field resistance line

. In summary, if a self-excited DC generator fails to run, it refers to resistance being greater than

critical resistance, field MMF that is not cumulative, or zero residual voltage.

_ 9.Centrifugal pumps, fans-blowers use __________

a) shunt as well as induction motor

b) only shunt motors

c) only induction motor

d) none of the mentioned

PERPLEXITY

Centrifugal pumps and fans-blowers use both shunt and induction motors, as well as only

induction motors

. Split-phase induction motors are commonly used in fans, blowers, centrifugal pumps, washing

machines, and grinders due to their low starting current and moderate starting torque

. The motor of a centrifugal pump is an electrical induction motor that converts electrical energy

into mechanical energy to drive the pump and move the water

. In summary, centrifugal pumps and fans-blowers use both shunt and induction motors, as

well as only induction motors, with split-phase induction motors being commonly used in these

applications due to their low starting current and moderate starting torque.

___ 10. Which method is/are used to perform magnetic locking?

I. Auxiliary motor II. Dc motor III. induction motor

a) I, II, III b) II, III c) II, I d) II

PERPLEXITY

Magnetic locking is performed using an electromagnet and an armature plate

. The locks work by creating a magnetic field that causes both the plate and the magnet to

attract to each other, forcing them to seal together and prevent doors from opening

. The magnetic field must be energized for the electromagnet lock to work properly, meaning

they require power to remain locked

. Magnetic locks can be opened with any electrical signaling method such as key code, swipe

card, motion sensor, or biometrics

. Therefore, magnetic locking does not involve auxiliary motor, DC motor, or induction motor. In

summary, magnetic locking is performed using an electromagnet and an armature plate, and it

does not involve auxiliary motor, DC motor, or induction motor.

___ 11. ___________ deals with behaviour of solid bodies subjected to various type of loading

a. Applied mechanics c. Axial load

b. Mechanics of material d. Tangential load

PERPLEXITY

The behaviour of solid bodies subjected to various types of loading is dealt with in mechanics of

materials.

. Mechanics of solids is a branch of applied mechanics that deals with the behaviour of solid

bodies subjected to various types of loading

material

. Solid mechanics studies how forces deform objects based on the objects' physical properties

. Axial load is a type of external load that causes stress near the point of loading to be much

higher than the average stress

. This leads to very complicated deformations from very complicated states of stress

. Tangential load is not mentioned in the search results. In summary, mechanics of materials

deals with the behaviour of solid bodies subjected to various types of loading, including axial

load, and tangential load is not mentioned in the search results.

12. Under stress-strain curve, linear region express:

a. Direct proportionality of stress-strain

b. Inverse proportionality of stress-strain c. Ductility of material

d. Plasticity of material

PERPLEXITY

The linear region of a stress-strain curve expresses direct proportionality of stress-strain

. In this region, stress and strain are proportional, and the slope is Young's modulus

. The linear region is the first stage of the stress-strain curve

. It is responsible for the linear portion of the stress-strain curve and is also known as the elastic

region

. The stress-strain curve consists of three distinct regions: the toe region, the linear region, and

the yield and failure region

. The toe region is responsible for the nonlinear stress/strain curve, and the yield and failure

region is the region where the material begins to deform plastically

. Ductility and plasticity of material are not specifically related to the linear region of the

stress-strain curve. In summary, the linear region of a stress-strain curve expresses direct

proportionality of stress-strain, and it is the first stage of the stress-strain curve, also known as

the elastic region.

___ 13. Structural component subjected to only tension or compression known as:

a. Repeated load

b. Statically Indeterminate structure

c. Axially loaded members

d. Inclined loaded beam

PERPLEXITY

A structural component subjected to only tension or compression is known as axially loaded

members

. Examples of axially loaded members include trusses, connecting rods, and columns

. Axially loaded members are structural elements that primarily deform in a one-dimensional

manner, meaning they change in length

. They are also referred to as flexible cables or coiled springs

. Axially loaded members carry some moment in addition to axial load, but for the purpose of

discussion, consideration is restricted to axial load only

. Repeated load, statically indeterminate structure, and inclined loaded beam are not related

to structural components subjected to only tension or compression. In summary, a structural

component subjected to only tension or compression is known as axially loaded members,

which include trusses, connecting rods, and columns, and they primarily deform in a

one-dimensional manner.

__ 14. ___________ relates lateral strain and axial strain

a. Hook’s law

c. Poisson ratio

b. Young Modulus

d. Volumetric ratio

PERPLEXITY

Poisson's ratio relates lateral strain and axial strain

. It is the ratio of transverse contraction (or expansion) strain to longitudinal extension strain in

the direction of the stretching force

. Poisson's ratio is defined as the negative of the ratio of transverse strain to lateral or axial

strain

. It is named after Siméon Poisson and is denoted by the Greek letter ‘nu’

. Poisson's ratio can be expressed as μ = - εt / εl, where μ is Poisson's ratio, εt is transverse

strain, and εl is longitudinal or axial strain

. The longitudinal strain can be expressed as εl = dl / L, where dl is the change in length and L is

the original length

. Hook's law relates stress and strain, Young modulus relates stress and strain in the linear

region of the stress-strain curve, and volumetric ratio

___ 15. Which one of the following is required equation for statically indeterminate structure

a. Equilibrium equation

b. Compatibility equation

c. Force-displacement relation d. All

PERPLEXITY

The required equation for statically indeterminate structure is force-displacement relation

. A structure is statically indeterminate when the static equilibrium equations, force and moment

equilibrium conditions, are insufficient for determining the internal forces and reactions on that

structure

. Statically indeterminate structures are structures in which the reaction forces and the internal

forces cannot be calculated by the three equilibrium equations

. More unknowns than equations are present in statically indeterminate structures, which require

additional equations to solve

. Compatibility equation is a type of additional equation required for the analysis of statically

indeterminate structures

. Equilibrium equation is not sufficient for finding the structure's internal forces and reactions in

statically indeterminate structu

. In summary, the force-displacement relation is the required equation for statically

indeterminate structure, and compatibility equation is an additional equation required for the

analysis of statically indeterminate structures.

___ 16. Twisting of straight bar when loaded by moment the results rotation of longitudinal axis:

a. Moment of inertia c. Slope

b. Torsion d. Deflection

PERPLEXITY

The twisting of a straight bar when loaded by a moment results in rotation of the longitudinal

axis, which is known as torsion

. Torsion is the twisting of an object due to an applied torque

. In torsion, the resultant shear stress in the section perpendicular to the torque axis is

perpendicular to the radius

. The maximum shear stress occurs on the surface of the shaft, where the radius is maximum

. The torsion equation for shafts of uniform cross-section unrestrained against warping is T/J =

Gθ/L, where T is the applied torque or moment of torsion, J is the polar moment of inertia, G is

the shear modulus of elasticity, θ is the angle of twist, and L is the length of the shaft

. Moment of inertia is a property of a cross-section that relates to an object's resistance to

bending, not torsion

. Slope is the angle of inclination of a line

. Deflection is the degree to which a structural element is displaced under a load

. In summary, torsion is the twisting of a straight bar when loaded by a moment, which results in

rotation of the longitudinal axis.

___ 17. Equation 𝑇/𝐼𝑝=𝐺𝜃/𝐿=𝜏/𝑅 , express

a. Torsion c. Moment diagram

b. Pure bending d. None

PERPLEXITY

The equation T Ip = Gθ L = τ R expresses torsion

. This equation is used to calculate the angle of twist in a beam of uniform cross-section along

the length when it is subjected to a torque

. T is the torque applied to the object, L is the length of the beam, G is the material's modulus of

rigidity, J is the torsional constant, θ is the angle of twist in radians, Ip is the polar moment of

inertia, and τ is the maximum shear stress at the outer surface

. The torsion equation is derived under certain assumptions, such as the material should be

homogeneous and should have elastic property throughout, the material should follow the

theory of Hooke’s law, and the material should have shear stress that is proportional to the shear

strain

. The equation for pure bending is M = σ I/c, where M is the bending moment, σ is the stress, I is

the moment of inertia, and c is the distance from the neutral axis

. Moment diagram is a graphical representation of the bending moment along the length of a

beam

. In summary, the equation T Ip = Gθ L = τ R expresses torsion, while pure bending is represented

by the equation M = σ I/c, and moment diagram is a graphical representation of the bending

moment along the length of a beam.

___ 18. A layer which neither elongate nor compressed due to bending of the beam: a. Upper

part of beam c. Centroid of beam b. Lower part of beam d. N9eutral surface

PERPLEXITY

The layer which neither elongates nor compresses due to bending of the beam is called the

neutral surface

. In mechanics, the neutral plane or neutral surface is a conceptual plane within a beam or

cantilever

. When loaded by a bending force, the beam bends so that the inner surface is in compression

and the outer surface is in tension. The neutral plane is the surface within the beam between

these zones, where the material of the beam is not under stress, either compression or tension

. The neutral surface of a beam is located where the cross-sectional area above the neutral

surface is equal to the cross-sectional area below the neutral surface

. The neutral axis is the bending line at which the neutral layer intersects the plane of bending

. The location of the neutral plane or surface can be an important factor in monocoque

structures and pressure vessels

. In summary, the neutral surface is the layer in a beam that neither elongates nor compresses

due to bending, and it is located within the beam between the zones of compression and

tension.

___ 19. The slope of certain beam at fixed end become:

a. Maximum c. Zero

b. Minimum d. Not possible to know

PERPLEXITY

The slope of a certain beam at the fixed end becomes zero

. The fixed end of a cantilever beam has a slope of zero degree

. A fixed beam is a beam that is restrained with a fixed support at both ends, and the slope of

fixed beams at both ends is zero

. The slope of a beam refers to the angle of deflection at a point on the beam, and it is a measure

of the beam's curvature at that point. The slope of a beam can be calculated using the equation

dθ/dx = M(x)/EI, where dθ/dx is the slope, M(x) is the bending moment at a distance x, E is the

modulus of elasticity, and I is the moment of inertia of the beam's cross-section

. In summary, the slope of a certain beam at the fixed end becomes zero.

___ 20. Method that provide way to determine the deflections of structure from strain energy of

the structure:

a. Mohr’s circle c. Strain energy theorem b. Castigliano’s theorem

d. Moment-Area method

PERPLEXITY

The method that provides a way to determine the deflections of a structure from the strain

energy of the structure is the strain energy theorem, which is based on Castigliano's theorem

. Strain energy is the internal energy in the structure due to its deformation, and it can be

calculated by the work done by the structure's member to deflect the member under the action

of external loads

. The strain energy method is used to calculate the deflections of a structure based on the

principle of Castigliano's theorem

. Castigliano's first theorem states that the first partial derivative of the total internal energy

(strain energy) in a structure with respect to any particular deflection is equal to the force

associated with that deflection

. Castigliano's second theorem states that the partial derivative of the strain energy with respect

to an applied force (or couple) is equal to the displacement (or rotation) of the force (or couple)

along its line of action

. The method of moments or moment-area method is used to determine the deflection of a

beam due to bending moments, while Mohr's circle is used to determine the principal stresses

and strains in a material under complex loading conditions

. In summary, the strain energy theorem, based on Castigliano's theorem, provides a way to

determine the deflections of a structure from the strain energy of the structure.

___21. Which one of the following is not correct about the difference between microcontroller

and microprocessor:

a. Microprocessor memory and I/O components connected externally

b. Microcontroller contain microprocessor and in built RAM, ROM, I/O device and timer

c. Microprocessor based system requires less hardware than microcontroller

d. Microprocessor power consumption is higher than microcontroller

PERPLEXITY

The correct option for the difference between microcontroller and microprocessor is

option c, which states that microprocessor-based systems require less hardware than

microcontroller-based systems

. The other options are correct statements about the difference between microcontroller and

microprocessor. A microprocessor is a processor where the memory and I/O components are

connected externally, while a microcontroller is a controlling device wherein the memory and I/O

output component are present internally

. A microprocessor consists of only a central processing unit (CPU), while a microcontroller

contains a CPU, memory, I/O, and timer all integrated into one chip

. Microprocessors are used in personal computers, while microcontrollers are used in

embedded systems

. Microprocessors use an external bus to interface with RAM, ROM, and other peripherals, while

microcontrollers use an internal controlling bus

. Microprocessors are complex and expensive, with many instructions, while microcontrollers

are inexpensive, straightforward, and have a small number of instructions to process

. Microprocessors have higher power consumption than microcontrollers

. In summary, the correct option is that microprocessor-based systems require less hardware

than microcontroller-based systems.

___22. ______________ is control registers that used to control different operation of PIC like

ADC, Serial Port, I/O Ports

a. Special function register c. File select register

b. Working register d. Status Register

PERPLEXITY

The control registers that are used to control different operations of PIC like ADC, Serial Port, I/

O Ports are called Special Function Registers (SFR)

. These registers perform various dedicated functions inside the PIC chip, and each special

function inside the PIC chip is controlled by using these registers

. The SFRs are memory registers that are used for special dedicated functions, and they are used

by the CPU and peripheral modules for controlling the desired operation of the device

. The SFRs are normally implemented in the form of static RAM memory, and they are classified

into two sets: core (CPU) and peripheral

. The core SFRs are associated with the core functions of the microcontroller, while the

peripheral SFRs are associated with the peripheral functions of the microcontroller

. The SFRs are closely tied to some special function or status of the processor, and they might

not be directly writable by normal instructions such as adds, moves, etc.

. Instead, some special instructions are required to modify them

. The SFRs are the gateway to interaction between the CPU and the peripherals, and they act

more or less like a bridge between the CPU and the peripherals

. In summary, the control registers that are used to control different operations of PIC like ADC,

Serial Port, I/O Ports are called Special Function Registers (SFR).

___23. The performance of CPU optimized by:

a. Maximizing cycles per instruction

b. Reducing number of instruction per program

c. Increasing the number of program per instruction

d. Optimization not required for CPU

PERPLEXITY

The performance of CPU is optimized by maximizing cycles per instruction and reducing the

number of instructions per program

. Optimizing the CPU is done through the Power Options section of the Control Panel in the

Windows operating system, where users can choose either "High Performance" or "Balanced" to

optimize the speed at which the CPU runs

. In addition, users can improve system performance by optimizing CPU resources, such as

using various compiler and linker optimization levels to generate more efficient user code

. Overclocking is another way to improve CPU performance, but it can be complicated and may

require upgrading other components

. Generally, optimizing CPU performance involves measuring both resource consumption and

wall clock time, and the biggest tradeoff is engineering time versus whatever is being optimized

for

. High CPU issues tend to be easier to fix by finding what's using the most CPU and making it use

less

. In summary, the performance of CPU is optimized by maximizing cycles per instruction,

reducing the number of instructions per program, and using various optimization techniques

such as compiler and linker optimization levels.

___24. Both microcontroller and microprocessor have the following BUS, except:

a. Address bus c. Data bus

b. Control bus d. System bus

PERPLEXITY

Both microcontroller and microprocessor have the following BUS:

Address bus,

Data bus, and Control bus

. The system bus is an internal bus that connects the processor with internal hardware devices,

and it is also called the "local" bus, Front Side Bus, or is sometimes loosely referred to as the

"memory bus"

. The data bus carries information to and from the processor element, and it carries instructions

from memory, input data from input devices, data stored into the memory, and outputs the data

into the output device

. The address bus carries addressing signals from the processor to memory, I/O (or

peripherals), and other addressable devices around the processor

. Control signals move out of the processor, but not in to it, and they are used to manage the

flow of data between the processor and other components

. The system bus is divided into three groups: the data bus, address bus, and control bus

. In summary, both microcontroller and microprocessor have the same three BUS: Address bus,

Data bus, and Control bus.

___25. Which one of the following used to reset microcontroller in the case of any software

malfunction:

a. Watchdog timer c. Flash program memory

b. CCP module d. Program counter

PERPLEXITY

The component used to reset microcontroller in the case of any software malfunction is the

Watchdog timer

. The Watchdog timer is a hardware timer that can be used to reset the microcontroller if the

software gets stuck in a loop or crashes

. When the Watchdog timer is enabled, it must be periodically reset by the software, and if the

software fails to do so, the Watchdog timer will expire and reset the microcontroller

. In addition, software reset can also be performed by using the AIRCR register for ARM

Cortex-M microcontrollers

. However, it is important to note that when the microcontroller is powered on, it undergoes a

Power On Reset (POR), which is a reset caused by the voltage supply, and it resets all the data in

the microprocessor

. In summary, the Watchdog timer is used to reset microcontroller in the case of any software

malfunction.