Hello peops. I have some opinions on qn 37..
My answer is B.
Based on research in wikipedia,
http://en.wikipedia.org/wiki/Electromagnets, under the title
Magnetic circuit, they say, " Most of
the magnetic field will be concentrated in the core." As
the strength of the field is determined by the number of field
lines present, at point Y ( the centre of the solenoid), there
should be strongest magnetic field strength when compared to the
points outside X and Z.
I think some people would choose A because they thought magnetic
effect on magnetic materials outside the core and magnetic field
strength is the same. It is right and logical when people thought
that the poles are the strongest because it attracts the most
magnetic materials ie iron filings, when compared to the core
ability to attract iron filings. I think the most probable
explanation for this is that the magnetic field lines within the
core is not "outside" when compared to the magnetic field lines at
the ends- where the magnetic field lines loop back from North pole
to South pole. As a result, the magnetic effect on
magnetic materials ,such as iron filings, is the strongest at the
poles and not at the core.\
In conclusion, the magnetic field strength should be the
strongest within the core and not at the ends. On the
other hand, the magnetic effect on magnetic materials such
as iron filings is the strongest at the ends and not at the core
physically.
Anyone thinks that it is improbable just comment. Thanks.