Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called ______．A.fluxB.polesC.magnetsD.azimuth
Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called ______．
A.flux
B.poles
C.magnets
D.azimuth
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单选题Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called（）.AfluxBpolesCmagnetsDazimuth
单选题To function properly, oil control rings used on a diesel engine piston must distribute sufficient oil to all parts of the cylinder wall and must also（）.Aprevent any lubricant from reachingBprevent excessive lubrication from reaching the combustion spaceCProvide metal-to-metal contact to seal the cylinder against blow-byDassure a positive means of scraping carbon accumulation from the cylinder
单选题This induced magnetism（）the permanent magnetism already present in the ship.Awill add toBwill subtract fromCmay add to or subtract fromDwill not change
单选题Prior to reading an aneroid barometer，you should tap the face lightly with your finger to（）.Aexpose any loose connectionsBdemagnetize the metal elementsCbring the pointer to its true positionDcontract and expand the glass face
单选题The magnetism in the various structures of a ship changing as a result of cruising，vibration，or aging is termed（）.Apermanent magnetismBsubpermanent magnetismCinduced magnetismDvariable magnetism
单选题When a vessel changes course from one cardinal heading to another cardinal heading whilea djusting the compass，which action should be taken?（）AThe course change should be made rapidly to prevent transient induced magnetism while passing the intercardinal headingsBAfter the new heading is reached，the vessel should steam on that course for at least two minutes before the adjustmentCDuring the course change，you should gently tap the compass to remove any error caused by friction on the pivot bearingDAfter steadying on the new heading，the compass card should be slewed by a magnet and allowed to oscillate freely to remove any gaussin error
单选题Why are the 1300 nm and 1550 nm regions of the fiber spectrum primarily used for optical communications?（）AThey are both regions of lowest loss.BThey are both regions of low reflections.CThey are both regions of low index of refraction.DThey are both regions of low chromatic dispersion.EThey are both regions of low Polarization Mode Dispersion (PMD).
单选题The Flinders bar on a magnetic compass compensates for the（）.Ainduced magnetism in vertical soft ironBinduced magnetism in horizontal soft ironCpermanent magnetism in ship's steelDvessel's inclination from the vertical
单选题The Flinders bar and the quadrantal spheres should be tested for permanent magnetism at what interval（）.AThey are not subject to permanent magnetism; no check is necessaryBSemiannuallyCAnnuallyDEvery five years
单选题A ship under construction or major repair will acquire permanent magnetism due to（）while sitting stationary in the earth’s magnetic field.Ahammering and jarringBvibration and poundingCvarying magnetic fieldsDstable or permanent magnetism of the ship
单选题Why are the 1300 nm and 1550 nm regions of the fiber spectrum primarily used for optical communications？（）A They are both regions of lowest loss.B They are both regions of low reflections.C They are both regions of low index of refraction.D They are both regions of low chromatic dispersion.E They are both regions of low Polarization Mode Dispersion （PMD）.