A material behaves as a superconductor below a critical temperature \( T_c \) and as a normal conductor above \( T_c \). A magnetic field \(\overrightarrow{B} = B\hat{z}\) is applied when \( T > T_c \). The material is then cooled below \( T_c \) in the presence of \( \vec{B} \). Which of the following figures represents the correct configuration of magnetic field lines?
The Correct Option is A, C
Solution and Explanation
,(C):
Top Questions on Magnetism and matter
A coil of 60 turns and area \( 1.5 \times 10^{-3} \, \text{m}^2 \) carrying a current of 2 A lies in a vertical plane. It experiences a torque of 0.12 Nm when placed in a uniform horizontal magnetic field. The torque acting on the coil changes to 0.05 Nm after the coil is rotated about its diameter by 90°. Find the magnitude of the magnetic field.
- CBSE CLASS XII - 2025
- Physics
- Magnetism and matter
A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.
- CBSE CLASS XII - 2025
- Physics
- Magnetism and matter
- Obtain the relation for magnetic dipole moment \( \mathbf{M} \) of a current-carrying coil. Give the direction of \( \mathbf{M} \).
- CBSE CLASS XII - 2025
- Physics
- Magnetism and matter
- A current-carrying loop can be considered as a magnetic dipole placed along its axis. Explain.
- CBSE CLASS XII - 2025
- Physics
- Magnetism and matter
- A diamagnetic substance is brought, one by one, near the north pole and the south pole of a bar magnet. It is:
- CBSE CLASS XII - 2025
- Physics
- Magnetism and matter
Questions Asked in GATE PH exam
A wheel of mass \( 4M \) and radius \( R \) is made of a thin uniform distribution of mass \( 3M \) at the rim and a point mass \( M \) at the center. The spokes of the wheel are massless. The center of mass of the wheel is connected to a horizontal massless rod of length \( 2R \), with one end fixed at \( O \), as shown in the figure. The wheel rolls without slipping on horizontal ground with angular speed \( \Omega \). If \( \vec{L} \) is the total angular momentum of the wheel about \( O \), then the magnitude \( \left| \frac{d\vec{L}}{dt} \right| = N(MR^2 \Omega^2) \). The value of \( N \) (in integer) is:
- GATE PH - 2025
- Rotational Motion
- The Hamiltonian for a one-dimensional system with mass \( m \), position \( q \), and momentum \( p \) is: \[ H(p, q) = \frac{p^2}{2m} + q^2 A(q) \] where \( A(q) \) is a real function of \( q \). If \[ m \frac{d^2 q}{dt^2} = -5q A(q), \] then \[ \frac{d A(q)}{d q} = n \frac{A(q)}{q}. \] The value of \( n \) (in integer) is:
- GATE PH - 2025
- Mechanics
- A system of three non-identical spin-\(\frac{1}{2}\) particles has the Hamiltonian
\[ H = \frac{A \hbar^2}{2} (\vec{S}_1 + \vec{S}_2) \cdot \vec{S}_3, \] where \( \vec{S}_1, \vec{S}_2, \vec{S}_3 \) are the spin operators of particles labelled 1, 2, and 3 respectively, and \( A \) is a constant with appropriate dimensions. The set of possible energy eigenvalues of the system is:- GATE PH - 2025
- Quantum Mechanics
- Potential energy of two diatomic molecules P and Q of the same reduced mass is shown in the figure. According to this diagram, which of the following option(s) is/are correct?
- GATE PH - 2025
- Potential Energy Curve
- Nuclear radiation emitted from a \( {Co}^{60} \) radioactive source is detected by a photomultiplier tube (PMT) coupled to a scintillator crystal. Which of the following option(s) is/are correct?
- GATE PH - 2025
- Radiation Detection