Permanent magnetism is caused by（）.

Permanent magnetism is found in ______.

A.hard iron

B.soft iron

C.vertical iron only

D.horizontal iron only

A ship under construction or major repair will acquire permanent magnetism due to ______ while sitting stationary in the earth's magnetic field．

A.hammering and jarring

B.vibration and pounding

C.varying magnetic fields

D.stable or permanent magnetism of the ship

Leakage of hydraulic fluid from around the shaft of a hydraulic motor may be caused by ______.

A.permanent loss of pump suction

B.worn shaft seals

C.high level in the oil sump

D.low motor RPM

A single vertical magnet placed underneath the compass in the binnacle is used to compensate for ______．

A.The horizontal component of the permanent magnetism

B.Deviation caused by the vessel's inclination from the vertical

C.Induced magnetism in the horizontal soft iron

D.Induced magnetism in the vertical soft iron

The magnetism in the various structures of a ship changing as a result of cruising，vibration，or aging is termed ______．

A.permanent magnetism

B.subpermanent magnetism

C.induced magnetism

D.variable magnetism

The permanent magnetism of a vessel may change in strength due to ______.

A.the nature of the cargo being carried

B.changes in heading

C.major structural repair

D.All of the above

What is used to correct for both induced and permanent magnetism，and consequently must be readjusted with radical changes in latitude ________．

A.Flinders bar

B.Soft iron spheres

C.Fore-and-aft permanent magnets in their trays

D.Heeling magnet

Permanent magnetism is caused by ______.

A.operation of electrical equipment and generators on board ship

B.the earth's magnetic field affecting the ship's hard iron during construction

C.the horizontal component of the earth's magnetic field acting on the horizontal soft iron

D.the vertical component of the earth's magnetic field acting on the vertical soft iron

The Flinders bar and the quadrantal spheres should be tested for permanent magnetism at what interval ________．

A.They are not subject to permanent magnetism; no check is necessary

B.Semiannually

C.Annually

D.Every five years

Before a magnetic compass is adjusted certain correctors must be checked to ensure that they are free of permanent magnetism．These correctors are the ______．

A.Fore-and-aft and athwartships magnets

B.Dip needle and heeling magnet

C.Heeling magnet and Flinders bar

D.Flinders bar and quadrantal spheres