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When the vibrating object moves backwards, it creates a region of low pressure in the medium called _______________.
Find the potential energy gained by a body of mass 60 kg, if it is raised by 12 m.(use g = 10 m/s²)
m=60 kg, g=10m/s2, h=12m
Potential energy= mgh
Light is a ______________ wave.
What is the effective resistance(in Ω) of two resistors 21 Ω and 28 Ω connected in parallel?
If the velocity of a body is doubled its kinetic energy ________________.
Then K.E'=m(2v)2/2 =2mv2
Propagation of sound can be visualized as propagation of _____________ variations in the medium.
Why is weightlessness experienced while orbiting the earth in space ships?
According to Dalton’s Atomic Theory, the smallest indivisible particles of matter is called ______.
Which statement(s) is/are CORRECT regarding Dalton’s Atomic theory?
I. All matters are made of very tiny particles.
II. Atoms of different elements have different masses and chemical properties.
III. The relative number of atoms is variable in any compound.
In a combination reaction there can be ______.
I. Two or more than two reactants
II. Two or more than two products
III. Only one product
Which of the following fuel has maximum caloriﬁc value?
If an atom has atomic number 10 and mass number 23, then what will be the number of protons and neutrons in an atom respectively?
Number of proton =10
Mass number =Number of proton + Number of Neutron
Number of Neutron=23-10
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that ______.
Atomic number is always equal to ______.
Which of the following statement(s) is/are INCORRECT?
I. Alkenes are fairly unreactive.
II. Alkenes burn with blue ﬂame.
III. Alkanes burn with yellow ﬂame.
Which place is NOT associated with Gautama Buddha?
Mir Hassan Dehlavi was in the court of which of the following?
During the Maratha period, who was the ofﬁcer responsible for the village administration?
Which of the following organizations was established outside India?
Who of the following leaders is NOT associated with Champaran Satyagraha?
‘Local Government’ is a subject mentioned in which list under the 7th schedule of the Indian constitution?
Comptroller and Auditor General of India submits the audit reports to _______.
Anti-defection law was passed in which Constitutional Amendment Act?
The word monsoon refers to ___________.
Which part of the Earth has the abundance of nickel and iron?
Konkan coast is stretched from where to where?
Which State declared Dolphin as State aquatic animal?
Sentinelese Tribe, which is in news recently, is located in the following islands?
Dikkibandi stadium was renamed after former Lok Sabha Speaker Purno A Sangma. It was located in the state of;
Which country has won the team event at the first Mallakhamb World Championship 2019?
Who has been conferred with the Gandhi Peace Prize for the year 2018?
Which among the following ministry gives Medini Puraskar every year?
Which among the following day is observed to commemorate the signature of the Montreal Protocol?
Which among the following is a correct definition of an Ecotone?
One of the major objectives of the National Water Mission is to increase the water use efficiency by 20%. Which among the following is the correct definition of water use efficiency?
Which among the following National Park is distinct in India because it encompasses a Project Tiger Reserve, an Elephant Reserve and a Biosphere Reserve(all of them)?
Which among the following National Park in India is also called the last house of White winged Wood Duck?
Which among the following is the most correct statement in context with Carbon footprint?
Which among the following countries is not a Non Annex I party to the UNFCC?
Which among the following World Heritage site of India is owned by two states?
A series circuit has 100 resistors, each having a resistance of 1 Ω and 1 A current is flowing through this circuit. What will be the current in the circuit when these 100 resistors are connected in parallel?
In parallel circuit sum of the currents through each path is equal to the total current that flows from the source.
Total resistor in the circuit = 100
The value of each resistor = 1 Ω
The current in each resistor when connected in series = 1 A
Source voltage = 1 × 100 = 100 V
The current in the circuit when these 100 resistors are connected in parallel = 100 × 100 = 10000 A
A 400 V, three-phase, four-wire is feeding a balanced load of 100 W lamp in each phase. If the lamp in one of the phases goes off. What will be the reading of the ammeter connecting neutrals of the supply and load?
If the lamp in one of the phases goes off, then total power = 300 × 0.57 = 171 W
∴ the reading of ammeter connecting neutrals = 171/400 = 0.43 A
Which of the following is a common name for the crime of stealing password?
Workbook is a collection of __________ in MS Excel?
Which PowerPoint view displays each slide of the presentation as a thumbnail and is useful for rearranging slides?
Which of the following is the fastest media of data transfer?
LANs can be connected by which of the following devices which operate on the data link layer?
In which process, each program is split into fixed size program components called pages?
Different icons of application software can be found in which bar in latest version of Microsoft Windows?
If a word is typed that is not in MS Word's dictionary, a wavy underline appears below the word. What is the color of the underline that appears in this situation?
Which line separates stator and rotor copper losses in circle diagram of an induction motor?
- It is the diagrammatic representation of the performance of the induction motor.
- It provides information about the power output, losses and the efficiency of the induction motor.
Significance of lines on the Circle Diagram:
Input line: The vertical distance between any point on the circle and the input line represent the input power.
Output line: The vertical distance between any point on the circle and the output line represents the output power.
Air gap power line: This line represents the air gap power. This line is also known as a torque line. It separates stator and rotor copper losses in the circle diagram.
The deflection sensitivity of the CRO is 10 m/V. What is the value of deflection factor (in V/m)?
Deflection factor (D) is reciprocal of sensitivity.
D = 1/s = 1/10 = 0.1 v/m
In a series RC circuit, the current ____ the voltage by an angle ____ degrees.
- In the pure capacitive circuit, the current leads the voltage by 90°.
- In a series RC circuit, the current leads the voltage by an angle between 0 to 90°.
- In the pure inductive circuit, the current lags the voltage by 90°.
- In a series RL circuit, the current lags the voltage by an angle the between 0 to 90°.
Find the maximum power is delivered to the load
What will be the flux density (in T) of material in free space if the field strength of the material is 2 × 105 A-m-1 and the magnetic susceptibility of the material is 0.44 × 10-3?
Magnetic flux density, B = μH = 4π × 10-7 × 2 × 105 = 0.25 T
Which of the following statement is true about RMS voltage?
- RMS voltage of a sinusoidal waveform is directly proportional to the peak voltage.
For a sinusoidal waveform,
- Multimeters measure average value of voltage and current of different waveforms.
- The RMS value of a sinusoidal waveform gives half of the heating effect than a DC current of the same value.
- The ratio of the RMS value of voltage to the maximum value of voltage is the same as the ratio of the RMS value of current to the maximum value of current.
Water pollution in rivers is measured by the dissolved amount of
- Water pollution in rivers is measured by the dissolved amount of oxygen
- BOD is used to measure water pollution as higher BOD means a higher amount of water pollution
- If the BOD of water is zero, then the water is safe to drink
Which of the following statements is true?
The velocity of sound is:
- The velocity of sound is more in summer than in winter because the sun evaporates more water from the surface, and as a result, the moisture in the atmosphere is more which makes the air to travel faster.
- Speed of sound is lower when density is higher.
- Sound waves are generated by causing pressure differences.
- It's high when pressure is high. Density over pressure gives temperature. Therefore, sound travels faster in summers.
An object is placed 100 cm in front of a concave mirror. The real image of the object is formed 50 cm in front of the mirror. What is the object's magnification?
V = -50
M = -V/U = 50/-100 = -0.5
Two coils of inductances 4 H and 6 H are connected in parallel. If their mutual inductance is 3H, calculate the equivalent inductance of the combination mutual inductance opposes the self-inductance.
L1 = 4H L2 = 6H M = 3H
Mutual inductance opposes the .
Mutual inductance assists the self-inductance
A 100 μH coil has a Q value of 200 at 2 MHz. The effective resistance of the coil is________.
Quality factor = 200, Frequency = 2 MHz, Inductance = 100 μH
We know that
Here f = Frequency, L = Inductance of coil, R = Resistance of coil
It is required to measure the true open circuit e.m.f. of a battery. The best device is
- A potentiometer is an instrument designed to measure an unknown voltage by comparing it with the unknown voltage
- The known voltage may be supplied by a standard cell or any other known voltage reference source
- It makes use of a balance or null condition, no current flows, and hence no power loss is consumed in the circuit
- Thus, the determination of voltage by a potentiometer is quite independent of the source resistance
- Measurements using comparison methods are capable of a high degree of accuracy because the result obtained does not depend upon the actual deflection of the pointer, as in the case of deflection methods
- Hence potentiometer is the best device to measure the true open circuit e.m.f. of a battery
Which one of the following is an example of an operating system?
It performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.
Some popular Operating Systems include Linux and Windows.
Windows Operating System
Every computer needs an operating system for operating a computer. There are few around, and Microsoft Windows is just one of them.
Some of the functions the Windows operating system allows to do are:
- Access applications (programs) on the computer (word processing, games, spreadsheets, calculators, and so on)
- Load any new programs onto the computer
- Manage hardware such as printers, scanners, mike, digital cameras
- Manage how files are stored on a computer (File Management, covered later in this module)
- Change computer settings such as colour schemes, screensavers, and the resolution of the monitor
There are several versions of Microsoft Windows in existence like Windows XP, Windows Vista, Windows 7 and Windows.
A transformer on no load has an induced emf of 230V (rms), draws a current of 2A (rms),that and having an angle between them is 60°, then the value of core loss is ________.
Core loss (PC) = VIC
IC = I cos ϕ
V is induced emf
I is current
ϕ is phase difference between induced emf and current
Given that, induced emf (V) = 230 V
Current (I) = 2 A
Phase difference (ϕ) = 60°
IC = I cos ϕ = 2 cos 60° = 1 A
Core loss (PC) = 230 W
To reverse the direction of rotation of a capacitor start motor while it is running, we should
To reverse the direction of rotation of a capacitor start motor while it is running, we should disconnect the motor from the supply till it stops then reconnect it to supply with the reversed connection of main or auxiliary winding.
Which of the following is true with regenerative braking?
Regenerative braking: In this type of braking back, Eb is greater than the supply voltage V, which reverses the direction of the motor armature current. The motor begins to operate as an electric generator.
Dynamic braking: In this type of braking, the DC motor is disconnected from the supply and a braking resistor Rb is immediately connected across the armature. The motor will now work as a generator and produces the braking torque.
Plugging: In this method, the terminals of supply are reversed, as a result of the generator torque also reverses which resists the normal rotation of the motor and as a result the speed decreases
In 4 wire electric circuit, the black conductor is used for
The split-phase induction motor has
- Split phase induction motors have low starting current and moderate starting torque
- So, these motors are used in fans, blowers, centrifugal pumps, washing machine, grinder, lathes, air conditioning fans, etc.
- These motors are available in the size ranging from 0.05 kW to 0.5 kW
The critical temperature above which ferromagnetic materials lose their magnetic property is known as
The magnetic susceptibility decreases with an increase in temperature. So, the ferromagnetism decreases with rising temperature. It is maximum at absolute zero temperature and becomes zero at Curie temperature. Above this temperature, the ferromagnetic material behaves as paramagnetic substance.
If α = 0.995, IE = 10 mA and ICO = 0.5 μA, then ICEO will be
ICEO = 100 μA
Low resistances are provided with four terminals
Four terminal measurements are used for low resistance measurement to avoid contact resistances and the effect of measuring instrument on a measured value.
Two outermost terminals are used to inject current in the low-value resistance. Voltage is measured across two inner terminals. This ensures that any contact resistance drop at current terminals does not affect voltmeter reading.
The value of low resistance is measured between the potential terminal P and P’.
For the network shown below, Norton’s equivalent current across AB is given by:
Let the short circuit current be Isc.
The circuit can be reduced as,
By using the current division rule,
An incandescent lamp is rated at 100 W, 230 V. What will be its resistance when measured with the help of a multimeter?
We know that
Here P = Power, V = Voltage, R = Resistance
A shunt resistor is connected across the contacts of a circuit breaker to:
- It is a method adopted for dampening the over-voltage transients due to current chopping.
- In this method, a shunt resistance is connected across the contacts of the circuit breaker.
- It reduces the rate of rising of re-striking voltage and the peak value of re-striking voltage.
- It helps to reduce the transient voltage surge during current chopping and capacitive current breaking.
A battery had a short-circuit current of 30 A and an open-circuit voltage of 24 V. If the battery is connected to an electric bulb of resistance 2 Ω, the power dissipated by the bulb is:
Open circuit voltage = VOC = 24 V, Short circuit current = ISC = 30 A
We know that
Resistance = VOC/ISC = 30/24 = 1.2 Ω
Current I = V/R = 24/3.2 = 7.5 A
The power dissipated by the bulb is = I2 x R = 7.52 x 2 = 112.5W
What does the fourth colour band on a resistor mean?
The impedance of an ideal parallel LC circuit at resonance is
In parallel resonant circuit at resonance frequency the impedance is maximum.
For parallel LC circuit
Y = 0
Since Y = 0 , Z = ∞
The current capacity of the battery depends upon
Anode acts as negative electrode; it is a material that undergoes oxidation during the cell discharge.
The cathode acts as a positive electrode; It is a material that undergoes reduction during the cell discharge.
Major aerosol pollutant in jet plane emission is
In troposphere,gaseous mixture containing oxygen, nitrogen, and carbon dioxide cycle in nature through
- The atmosphere is the thin layer of gases separating earth from the outer space
- The lower atmosphere is a mixture of molecules of three important gases: Oxygen (O2), Nitrogen (N2), and Carbon dioxide (CO2), along with water vapor and trace amounts of several other gases that have no immediate biological importance
- The gaseous mixture of the troposphere (the lowest layer of atmosphere in which living organisms operate) is called air containing oxygen, nitrogen, and carbon dioxide, all of which cycle in nature through biogeochemical cycles
- We live in a biological ecosystem that shows a constant flow of energy between various organisms
- There is an exchange of nutrients, which translates to exchange of energy
- Nutrients ultimately are chemical compounds. So, there is this natural pathway where the living matter is constantly circulated
- Nutrients are never lost from an ecosystem; Recycling of these nutrients happens at every stage
- This recycling of the nutrients through different components in an ecosystem is called the nutrient cycle or biogeochemical cycle
Where are the Buddhas of Bamiyan located?
- The Buddhas of Bamiyan is located in the Hazarat region of Afghanistan.
- Buddhas of Bamiyan are 2 statues of Gautama Buddha made in the 6th century.
- The statues are made in the Gandharan Style of Architecture.
- The Taliban destroyed them in the year 2001.
Which article of the Constitution of India ensures the freedom of the press?
- Article 19 of the Constitution of India ensures the freedom of the press.
- The Indian Constitution ensures that all citizens have the right to freedom of speech and expression.
A Satellite has a mass of 100 kg and is initially travelling at 2.64 × 103 m/s . To correct its orbit, a thruster is fired for 2.25 seconds which changes the speed of the satellite to 4.89 × 103 m/s.
The force generated by the thruster is:
If there are three resistances each of 2 ohm and generate the effective resistance of 3 ohm so how will the connection of the three resistances in the circuit?
R’ = 2 || 2 = 1 Ω
Connecting this combination in series with 2 Ω resistance gives
Req = R’+ 2 = 1 + 2 = 3
Hence, A parallel combination of two resistance (which will be 1 ohm) joined in series with the third resistance (2 ohm)
Potier triangle is required to calculate voltage regulation in which of the following method?
- The Potier triangle determines the voltage regulation of the machines
- This method is also called a zero power factor (ZPF) method
- This method depends on the separation of the leakage reactance of armature and their effects
- The graph of the Potier triangle is shown in the figure below
- The triangle formed by the vertices a, b, c has shown below in the figure is called Potier triangle
If the slip of an induction motor is 100% then what will its speed be?
The difference between the rotor speed (N) and the rotating magnetic flux speed (Ns) is called slip.
The induction motor slip is usually expressed as a percentage of synchronous speed (NS) and is represented by the symbol s.
Mathematically, Percentage slip,
Or fractional slip,
At start, N = 0, therefore, Slip,
At synchronous speed, Slip,
For the circuit shown below, find the current (in A) produced by the 50 V battery.
I1 = 50/3.75 = 13.33 A
I2 = 50/7.5 = 6.66 A
Total current (I) = I1 + I2 = 20 A
Potentiometer sensitivity can be increased by
Sensitivity of potentiometer is the smallest potential difference that can be measured using the potentiometer. It can be increased by decreasing its potential gradient. Thus, it can be increased by the following methods.
1) By increasing the length of the potentiometer wire as the length of the wire is directly proportional to resistance.
2) If the potentiometer wire is a fixed length, the potential gradient can be decreased by reducing the current in the circuit by varying rheostat.
What is the power factor of the circuit when a current of 8 A flows in the ac circuit when 100 V dc is applied to it whereas it takes 125 V ac to produce the same current?
cosϕ = 100/125 = 0.8
Active power (measured in Watt) is actual power or true power which does the useful work. (so, most of the equipment’s which consume electricity or electric power are rated in terms of Watt or HP)
Reactive power (measured in Volt-Ampere- Reactive) is imaginary power thata the is required for the processes like energy conversion & energy storage. (so, the equipment’s which generate only reactive power are rated in terms of VAr. e.g. capacitor banks for pf correction)
Apparent power (measured in terms of Volt-Ampere) is total power. And is combination of active and reactive powers
An induction meter can handle current upto
- Induction type of energy meter are universally used for measurement of energy in domestic and industrial A.C circuit
- The unit of electrical energy is kilowatt hour (KWh)
- Induction type of energy meter used is based on the “electromagnetic induction” principle
- They are known as induction type instruments
- An induction meter can handle current up to 100 A
In a Zener diode with high breakdown voltage
The carbon arc welding has the advantages of:
Advantages of carbon arc welding:
- The heat developed during the welding can be easily controlled by adjusting the length of the arc
- It is quite clean, simple, and less expensive when compared to other welding processes
- Both the ferrous and non-ferrous metals can be welded
- Easily adaptable to automation
Disadvantages of carbon arc welding:
- Input current required in this welding, for the workpiece to raise its temperature to welding temperature, is more
- In case of ferrous metal, there is a chance of disintegrating the carbon at high temperature and transfer to the weld, which causes weld deposit to be harder and brittle
- A separate filler rod has to be used if any filler metal is required
Find the current I shown in the figure
Consider 10 V source and open the current source.
Now consider current source and inactive the voltage source.,
I2 = 5 A
∴ Total current I = I1 + I2 = 1 + 5 = 6 A
The lamp used in cinema projector is:
Which of the following statements correctly defines "Utilization factor" or "Co-efficient of Utilization"?
Coefficient of utilization or utilization factor: It is defined as the ratio of a total number of lumens reaching the working plane to the total number of lumens emitting from the source.
Maintenance factor: It is defined as the ratio of illumination under normal working conditions to the illumination when everything is clean.
Its value is always less than 1, and it will be around 0.8. This is due to the accumulation of dust, dirt, and smoke on the lamps due to which they emit less light than that they emit when they are clean. Frequent cleaning of the lamp will improve the maintenance factor.
Depreciation factor: It is defined as the ratio of initial illumination to the ultimately maintained illumination on the working plane.
Depreciation factor = 1 / maintenance factor
Its value is always more than 1.
200 V DC motor draws an armature current of 25 A. Its armature resistance is 0.8 ohm. The induced emf in the motor will be:
In a DC generator, generated emf is given by
Eg = Vt + IaRa
In a DC motor, back emf is given by
Eb = V – IaRa
Where, Ia is armature current
Ra is armature resistance
Armature current (Ia) = 25 A
Armature resistance (Ra) = 0.8 ohm
Voltage (V) = 200 V
Ea = V – IaRa = 200 – 25(0.8) = 180 V
If a phase sequence indicator rotates clockwise for a phase sequence of RYB, then what happens when the phase sequence is changed to BRY
- If a phase sequence indicator rotates clockwise for a phase sequence of RYB if the phase sequence is changed to BRY It will rotate clockwise only because there is no change in phase sequence.
- The direction of AC motor can be reversed by interchanging any two of the three motor supply lines
- Let the phase sequence of the three-phase voltage applied to the stator winding is RYB
- If this sequence is changed to RBY, it is observed that the direction of rotation of the field is reversed i.e., the field rotates in the opposite direction
- However, the number of poles and the speed at which the magnetic field rotates remain unchanged
The expansion of WAN is _________.
1. Local Area Network (LAN):
- Networks used to interconnect computers in a single room, rooms within a building or buildings on one site are called LAN
- LAN links computers i.e. software and hardware, in the same area for the purpose of sharing information
- Usually, LAN links computers within a limited geographical area because they must be connected by a cable
2. Wide Area Network (WAN):
- Computer network spanning a regional, national or global area
- The distance between computers connected to WAN is larger
- Therefore the transmission mediums used are normally telephone lines, microwaves and satellite links
Which of the following digital personal assistant used in Windows 10?
- A digital personal assistant is a software-based service that resides in the cloud, designed to help end users complete tasks online
- In 2015 Microsoft released Windows 10, which came with Cortana, a digital personal assistant like Apple’s Siri
- Alexa is a personal assistant developed by Amazon released in Nov 2017
- The Google Assistant is personal assistant developed by Google that is primarily available on mobile and smart home devices; It was first debuted in May 2016
The pH of acid rain should always be less than
We are aware that normally rainwater has a pH of 5.6. When the pH of the rainwater drops below 5.6, it is called acid rain.
Acid rain refers to the ways in which acid from the atmosphere is deposited on the earth’s surface. Oxides of nitrogen and sulphur which are acidic in nature can be blown by the wind along with solid particles in the atmosphere and finally settle down either on the ground as dry deposition or in water, fog and snow as wet deposition.
The bad effects of acid rain
- When acid rain falls and flows as groundwater to reach rivers, lakes etc, it affects plants and animal life in the aquatic ecosystem
- Acid rain is harmful to agriculture, trees and plants as it dissolves and washes away nutrients needed for their growth
- It causes respiratory ailments in human beings and animal
- It may also cause corrosion in many buildings bridges, monuments, fencing etc
- It causes irritation in the eyes and skin of human beings
- This rain reduces the lustre of the metals too
- Acid rain damages buildings and other structures made of stone or metal
- The Taj Mahal in India has been affected by acid rain
If the capacitor of a single phase motor is short circuited_________.
Root locus is used to calculate____.
A step up chopper has input voltage 110V and output voltage 150V: the value of duty cycle is-________.
Where, E0 = output voltage
α = duty cycle
Under which conditions an initially relaxed system does becomes unstable?
BIBO – In this system bounded input produces bounded output. Usually these systems are considered as stable system. This kind of systems are also linear systems i. e. output is directly proportional to the input and at initial state zero output.
Which type of charge carrier has the greatest mobility in semiconductor?
NOTE- semiconductor is negative temp coeffient.
Semi conductor is made form 4th group element,like ge ,si.
In Indus Valley Civilization, site Dholavira, has been located in which state of India?
Which binary value equals 2-2 ?
Step 1: Multiply the fractional part by 2.
0.25 x 2 = 0.5
the whole number part of the result is the first binary digit to the right of the point.
Step 2: Discard whole number part and repeat step 1.
5 x 2 = 1.0
Which among the following is the weakest base?
Which one of the following is not alkaline?
find the resultant resistance when 3 resistance of 2 ohm each are connected as shown in the figure below.
the resultant resistance =
= 1.33 Ohm
Which test is not conducted on line conductor before energization and after installation?
Zener diode are used primarily as……
Maintain output voltage constant. But during voltage across the diode is reverse bias, then diode act as Zener diode operates in the reverse blocking mode for maintaining output voltage stable.
Therefore Zener diode is called a voltage regulator.
IGBT combines advantages of_____________.
The IGBT combines the simple gate-drive characteristics of MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device.
In a.c system, the skin effect_________.
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor.
Overall efficiency of gas turbine is________.
Ideal load factor should be________.
Atomic power station of India, which is built completely indigenously?
Air Quality Early Warning System launched in Delhi can predict extreme air pollution alerts by how many hours in advance?
Which one of following does not affect the sag?
The wattmeter measures________ power.
An XOR gate produces output only when two inputs are___________.
XOR gate produces the result irrespective of the magnitude of the input. So, low or high input does not make any difference.
X Y OUTPUT
0 0 0
0 1 1
1 0 1
1 1 0
For the process of electrolysis ,we require_______.
A transistor is ……………operated device.
Change in base current is main responsible for change in output of circuit volage and current.
There for BJT is current control device.
Note-FET is voltage control device
The flux density B in a core having relative permeability μr and length l meters when I amperes of current flows in its N turn windings is_________.
Electric Flux Density is the amount of electric flux, the number of "lines," passing through a
given area. Units are Gauss/square meter.
Synchronous motors are generally used in application requiring_________.
For variable speed applications, DC motors are used as they could provide the wide range of speed.
Whereas, Induction motors are used for frequent start and stop applications.
The B – H curve of _______ will not be straight line.
curve between current and flux is linear for good conductor & non linear for bad conductor.
linearity decreasing order
air> copper> silicon steel>soft iron.
An alternating voltage or current is a___________.
The quantity represented by value and displacement is termed as Phasor whereas the one represented by value and direction is termed as the vector quantity.
Because it act like rotating vector so it is Phasor quantity and not vector.
Which of the following enjoys the legal supremacy in India?
Mac OS was introduced by-
Which of the following is NOT a cause of air pollution?
The D.C armature resistance of a delta connected alternator measured across its two terminates is 1Ω. The per phase DC resistance is________.
The superposition theorem applies to________.
Current & voltage are linear to each other.
but power = I2 x R
Power is direct propositional to square of current , which is non linear.
There for it is applicable only for current &voltage calculation.
Permissible pH value of water for the boiler is_________.
Natural water is usually between 6.5 and 7.5 pH. A common recommendation is to maintain boiler water at 8.5 pH.Acidic water is corrosive. Alkalinic water is more prone to scaling.Alkalinity is a measure of the bicarbonate (HCO3) , carbonate (CO3) and hydroxyl (OH) ions in the water.
The forward voltage drop across a silicon diode is about_________.
during reverse bias it act as open circuit.it offer infinity resistance.
AND for ge diode is about 0.3v.silicon diode has greater thermal stability than ge diode.
If, |Z|>1 for K>0 then z-1[E/(Z2 + 1)] is
z-1[f(z)] = sin(π/2)k
For insulation resistance test of 11v insulator what should be voltage range of 5WHV megger?
A crystal diode is__________ device.
High speed alternators are driven by_____________.
The alternator with large diameter and small length of rotor is used for low speed aplication.This type of rotor is driven by hydraulic or diesel engine.
Transistor turn off time is_______.
Circuit turn off time is always greater than device turn off time.
Becouse gate circuit require some time recovery purpose.
For proper circuit operation.otherwise it turn on any time.this is causes maloparation of circuit.
Circuit turn off time =device turn off time+gate recovery time.
What title did the British confer Gandhi with, which was relinquished by him?
If area of hysteresis loop of a material is large, the hysteresis loss in the material will be________.
Hysteresis loss is directly proportional to the area under the curve on B-H axis.
The capacitance of reversed biased junction J2 in thyristor is Cj2 = 20 pf and can be assumed to be independent of the off side voltage. The limiting value of the charging current to turn on the thyristor is 16mA. What is critical value of dv/dt?
Then = 800 V/us
The curie temperature of iron is___________.
The rotor of the hysteresis motor is made of magnetic material having area of hysteresis loop_____.
The rotorRotor of the hysteresis motor is made of hardeningharden steel with high retentivity.
High retentivity is responsible for a large hysteresis loop on B-H curve.
Velocity of sound waves in air is 330 m/s. For a particular sound wave in air, a path difference of 40 cm is equivalent to phase difference of 1.6π . The frequency of this wave is-
__________ is used as a programming language in first generation computers?
The radiation emitted by black bodies is explained by_______?
The reluctance of magnetic circuit varies as_________.
Reluctance, therefore reluctance varies as length/ Area.
A GTO can be turned on by applying______________.
For the same rating, the size of 1Φ IM is about______that of 3Φ IM.