NEET Physics MCQs

A bar magnet of magnetic moment $M$ and moment of inertia $I$ is suspended in a uniform magnetic field $B$. If it is displaced slightly from its equilibrium position, its time period of oscillations for small angular displacement $heta$ is $T_1$. Now, if another identical magnet is glued to the first magnet along its length with the like poles together, the new time period of oscillations for small angular displacement is $T_2$. The ratio $\frac{T_1}{T_2}$ is:

A short bar magnet is placed in a non-uniform magnetic field with its magnetic moment making an angle $heta$ with the direction of the field. It experiences:

Two identical short bar magnets, each of magnetic moment $M$, are placed perpendicular to each other at a separation $d$. The magnitude of the magnetic field at a point midway between them is:

A bar magnet is suspended freely in a uniform magnetic field. What is the net force acting on the magnet?

The couple acting on a bar magnet in a uniform magnetic field is independent of:

A thermocouple using iron and copper produces an emf of $E_1$ when its junctions are kept at $0^\circ C$ and $100^\circ C$. If the cold junction is kept at $-20^\circ C$ and the emf is $E_2$, what is the temperature of the hot junction?

A pyrometer is calibrated to measure temperatures in the range of 500°C to 2500°C. Which of the following is NOT a valid reason for choosing a pyrometer over a thermocouple in this temperature range?

The dimensions of couple are

If C is the restoring couple per unit radian twist and I is the moment of inertia, then the dimensional representation of $2{\rm{\pi }}\sqrt {\frac{I}{C}}$ will be

If C is the restoring couple per unit radian twist and I is the moment of inertia, then the dimensional representation of $2{\rm{\pi }}\sqrt {\frac{I}{C}}$ will be