Related Questions

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
Invar tapes used for measuring base lines, is made of nickel-iron alloy containing nickel
A 24 %
B 36 %
C 40 %
D 60 %
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
Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is
A 12
B 36
C 54
D 68
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
The use of permanent magnets is. not made in
A magnetoes
B energy meters
C transformers
D loud-speakers
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
Addition of __________ to the steel helps in increasing the residual magnetism in steel used for making magnets.
A Chromium
B Nickel
C Tungsten
D Cobalt

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