percdc cns ee4

8/10/2019 Percdc Cns Ee4

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CNS-EE4 Instrumentations / Energy Conversion / Others

1. An instrument which depends on current in one or more fixed coils acting on one or morepieces of soft iron, at least one of which is movable.

moving-iron instrument

2. What is that device which depends on the action of a movable permanent magnet inaligning itself in the resultant field produced either by a fixed permanent magnet and

an adjacent coil or coils carrying current or by two or more current-carrying coilswhose axes are displaced by a fixed angle?

moving-magnet instrument

3. What ammeter is mostly used in measuring high-frequency currents?thermocouple

4. his instrument measures temperatures by electric means, especially temperatures beyondthe range of mercury thermometers.

pyrometer

. his instrument refers to that one which measures the intensity of the radiationreceived from any portion of the s!y

pyranometer

!. A device used to mechanically measure the output power of a motor."ynamometer

#. An indicating instrument whose movable coils rotate between two stationary coils,usually used as wattmeter.electro"ynamometer

$. "rror in ohmmeter reading is due to %attery aging

&. Which of the ammeter below that has no insertion error?clamp-meter

1'. o prevent damage of the multirange ammeter during selection, a#an $$$$$$$$$ shouldbe used.

(yrton shunt

11. %oltage measurement in a high impedance circuit requires a voltmeter withhigh input impe"ance

12. &f a meter with a full-scale current of '((uA is used as an ac voltmeter with half-wave rectification, its ac sensitivity is4)'' */+

13. he )ero-adjust control in an analog type ohmmeter is used to

compensate ,or the "i,,ering internal %attery voltage

14. *ynamometers are mostly used as attmeter

1. What damping method is generally used in dynamometers?air ,riction

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1!. Which dynamometer instrument has a uniform scale? attmeter

1#. +or a dynamometer to be able to measure high current, a $$$ should be used.current trans,ormer

1$. he scale of a hot wire instrument is a#an $$$$$$$$ function.suare"

1&. oving iron instruments have a scale function that issuare"

2'. o increase the measuring capability of a moving-iron ac meter, a $$$$ should beused."i,,erent num%er o, turns o, operating coil

21. Which electrical instruments below is the most sensitive?00C

22. ontrolling torque in .

spring action

23. What damping method is used in induction type ammeters?electrostatic "amping

24. &nduction type instruments are mostly used as att-hour meter

2. he force/s0 that is/are0 acting on the pointer of an indicating instrument as theyrest on there final deflected position. /1ote2 damping torque is (0.controlling "e,lecting torues

2!. What is /are0 the force/s0 acting on the pointer of an indicating instrument when it

is in motion?controlling) "amping) an" "e,ecting torues

2#. A 3elvin electrostatic voltmeter uses what method of damping?,lui" ,riction

2$. &n a moving coil ammeter, a $$$$$$$$ is connected in series with the coil tocompensate for temperature variations.samping resistor

2&. What is this measuring instrument that uses the force of repulsion between fixed andmovable magneti)ed iron vanes, or the force between a coil and a pivoted vane-shapedpiece of soft iron to move the indicating pointer?

vane-type instrument

3'. &ts an electrostatic voltmeter in which an assembly of figure 4 5 4 shaped metalplates rotates between the plates of a stationary assembly when a voltage is appliedbetween the assemblies. he length of the arc of rotation is proportional to theelectrostatic attraction and thus, to the applied voltage.elvin voltmeter

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4. Which winding in a dc-compound generator that is relatively made of fine wires?shunt ,iel" in"ing

4!. What is the primary reason why carbon brushes are preferred over copper brushes indc motors?they pro"uct less arcing

4#. o minimi)e arcing during starting of dc motors, a resistance should be added tolimit the current in the $$$$armature in"ing

4$. otors whose speed can be easily controlled."c motors

4&. When a dc motor has no load, what will happen to the bac! emf? %ecomes maimum

'. When can we get a maximum mechanical power from a dc motor?E% 7 '.+

1. :ne cause why the shaft torque is less than the developed armature torque of a dcmotor.,riction loss

2. onsidered as a variable speed motorseries

3. What is the most common method used in varying the sped of a dc motor? %y varying the ,iel" strength

4. &n choosing a motor for a particular application, what characteristic you shouldconsider?spee"-torue

. A motor whose speed increases as the load is increased."i,,erentially compoun"e"

!. +actor/s0 that affect iron losses in a dc motor.,lu ,ie" are correct

#. :ne advantage of a cumulatively compounded motor is that it does not run widely atlight loads, this feature is due toshunt in"ing

$. &n applications where an almost constant speed is required, a $$$$$$ motor is a goodchoice.

"c shunt

&. &n applications where a high torque is needed during starting, a $$$$$$ motor ispreferred."c series

!'. &n applications where sudden heavy loads happen for short duration, a $$$$$$ motoris the best choice.cumulatively compoun"e"

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#. he law that spar!ling potential between two parallel place electrodes in a gas & afunction of the product of the gas density and the distance between the electrodes.either aschen9s rule or aschen9s la is right

#!. he rule that hysteresis loss in a magnetic material varies directly in proportionwith the cube of the magnetic induction.>ayleigh9s la

##. he thermal-radiation law that shows the total emissive power of ablac!body to beproportional to the fourth power of the absolute temperature of the body.Ste,an-:olt?mann la

#$. he wavelength of luminescence excited by radiation is always greater than that ofthe exciting radiation.Sto8e9s la

#&. &t is a law expressing the relationship nbetween a stimulus and the physiologicalreaction ir produces2 he sensation is proportional to the logarithm of the stimulus

5e%er-@echner la

$'. he law indicating that the wavelength of maximum radiation of a blac!body isinversely proportional to the absolute temperature.either 5ien9s ,irst la or 5ien9s "isplacement la

$1. he law showing that the emissive power of a blac! body is proportional to the fifthpower of absolute temperature is !nown aseither 5ien9s ra"iation la or 5ien9s secon" la

$2. &t is an empirical law for the spectral distribution of energy radiated from a blac!body at a specified temperatre.

5ien9s thir" la

$3. An electromagnetic wave will ta!e a path that involves the least travel time when

propagating between two points.@ermat9s principle

$4. he rule that states, during transitions of orbital electrons from higher to lowerenergy states /accompanied by the emission of the photons0, changes in the innerquantum number may not only e by a factor of ( r =#- '.< rule

$. his is an extension of the two-fluid model of superconductivity, in which it isassumed that superfluid electrons behave as if the only force acting on them arisesfrom the applied electric fields, and that the curl of the superfluid current vanishesin the absence of a magnetic field.=on"on supercon"uctivity theory

$!. A formula for the overall transmittance of a signal flow graph in terms oftransmittances of various paths in the graph.

0ason9s theorem

$#. his applied to a nonradiative transition of an tom from an excited energy state toa lower energy state, accompanied by the emission of an electron

(uger e,,ect

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$$. 6efers to the selective absorption of electromagnetic waves by a dielectric, due tomolecular dipolesAo%ye e,,ect

$&. he rotation induced in a freely suspended ferromagnetic object when magneti)ationof the object is reversed.Einstein-"e as e,,ect

&'. he random variations in the output current of an electron tube that has an oxide-coated cathode, caused by random changes in cathode emission.,lic8er e,,ect

&1. What do you call of the momentary illumination produced when an electric field isapplied to a phosphor previously excited by ultraviolet radiation?;u""en-ohl e,,ect

&2. he ability of ultraviolet radiation to discharge a negatively charged body in avacuum.allachs e,,ect

&3. he phenomenon whereby current in a gas changes as the result of irradiation bylight is called<oshi e,,ect

&4. he variation /caused by the earth>s magnetic field0 of the strength of cosmic raysarriving at different longitudes on the surface of the earth is !nown aslongitu"e e,,ect

&. his is the effect when the magneti)ation of a helically wound, ferromagnetic wirefluctuates, the tendency for a potential difference to occur.

0ateucci e,,ect

&!. $$$$$$$ refers to the scattering of monochromatic light /light of a single

wavelength0 when passed through a transparent substance.>aman e,,ect

&#. his is the ability of an electric current to destroy superconductivity by themagnetic field that it generates, without raising the cryogenic temperature.Sils%ee e,,ect

&$. "lectric polari)ation of a dielectric material being moved in a magnetic field. 5ilson e,,ect

&&. What is the two-terminal semi-conductor device which resembles the behavior of aneuron and allows machines to duplicate some of the neurological phenomena observed inthe human body?

neuristor

1''. What gadget that electronically aids the blind which has a camera that scan printedmatter and a device forms corresponding raised letters which can be read with thefingertips?optacon

1'1. What do you call of a monostable pentode circuit that generates sharp pulses at anadjustable and accurately timed interval after receipt of a triggering signal?

phantastron

# o, $

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