Question 81:
easy23. The magnetic moment of a diamagnetic atom is: (2010 Mains)
In diamagnetic materials, all electrons are paired, and the magnetic moments of paired electrons cancel each other out completely in every atom. Hence, each diamagnetic atom has zero net magnetic dipole moment.
Question 82:
easy24. If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is: (2009)
Diamagnetic materials tend to move from regions of stronger magnetic fields to weaker magnetic fields. Since the magnetic field is strongest near both poles, the substance is repelled by both the north and south poles.
Question 83:
easy25. If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by $\mu_d$, $\mu_p$ and $\mu_f$ respectively, then (2005)
Diamagnetic atoms have completely paired electron configurations, leading to a net atomic dipole moment $\mu_d = 0$. Paramagnetic atoms have unpaired electrons giving a permanent non-zero atomic dipole moment $\mu_p \neq 0$.
Question 84:
easy26. Diamagnetic material in a magnetic field moves: (2003)
Diamagnetic substances are magnetized in a direction opposite to the external magnetizing field. As a result, they experience a repulsive force from strong field regions toward weaker field regions.
Question 85:
easy27. Among which the magnetic susceptibility does not depend on the temperature: (2001)
Diamagnetism is an intrinsic property arising from the orbital motion of electrons and does not involve the alignment of permanent atomic dipoles against thermal agitation. Hence, its susceptibility is independent of temperature.
Question 86:
easy28. For protecting a magnetic needle it should be placed: (1998)
To shield a region from external magnetic fields (magnetic shielding), the object should be enclosed in a ferromagnetic enclosure such as a soft iron box, which channels magnetic field lines through its walls.
Question 87:
easy29. Electromagnets are made of soft iron because soft iron has: (2010 Pre)
An electromagnet should easily magnetize when current is switched on and readily lose its magnetism when current is turned off. Thus, the material must have low retentivity and low coercivity.
Question 88:
easy30. Curie temperature is the temperature above which: (2008)
Curie temperature is the critical temperature above which thermal agitation destroys the domain structure of a ferromagnetic material, converting it into a paramagnetic material.
Question 89:
easy31. Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show: (2007)
When a ferromagnetic substance like nickel is heated beyond its Curie temperature ($T_C$), domain alignment is disrupted by thermal energy, and it behaves as a paramagnetic substance.
Question 90:
easy32. Above Curie temperature: (2006)
At temperatures higher than the Curie temperature, spontaneous magnetization in ferromagnetic materials vanishes and the substance transforms into a paramagnetic material obeying Curie-Weiss law.