Related Questions

Permanent magnets are made of high carbon steel and
A 15% of cobalt
B 20% of cobalt
C 35% of cobalt
D 45% of cobalt
Permanent magnets are normally made of
A Alnico alloys
B Aluminium
C Cast iron
D Wrought iron
Materials used for making permanent magnets containing iron and nickel are made by __________ technique.
A Powder metallurgy
B Casting
C Forging
D None of these
Those materials are well suited for making permanent magnets which have ________ retentivity and ________ coercivity.
A Low, high
B High, high
C High, low
D Low, low
Hard steel is suitable for making permanent magnets because
A It has good residual magnetism
B Its hysteresis loop has large area
C Its mechanical strength is high
D Its mechanical strength is low
Which of the following memories contains a thin film of magnetic material sandwitched between two permanent bias magnets?
A ROM
B Magnetic disk
C Core memory
D Bubble memory
E None of the above
Alnico, an alloy used extensively for permanent magnets contains iron, nickel, aluminium and cobalt in the following ratio
A 50 : 20 : 20 : 10
B 40 : 30 : 20 : 10
C 50 : 20 : 10 : 20
D 30 : 20 : 30 : 20
If a bar magnet is __, the two pieces form two complete magnets, each with north and south pole.
A broken
B broke
C breaking
D break
_________ electromagnets generally function as holding magnets.
A Tractive
B Portative
C Either of the above
D None of the above
Temporary magnets are used in
A loud-speakers
B generators
C motors
D all of the above

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