Related Questions

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
The materials having low retentivity are suitable for making
A weak magnets
B temporary magnets
C permanent magnets
D none of the above
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
Those magnetic materials are best suited for making armature and transformer cores which have ________permeability and _________hysteresis loss.
A High, high
B Low, high
C High, low
D Low, low
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
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
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
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
Water retentivity for brick masonry should not be less than
A 50%
B 60%
C 70%
D 80%

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