Torque on a Dipole
Q. If the bar magnet in exercise 5.13 is turned around by 180°, where will the new null points be located?
Q. A bar magnet of magnetic moment 1.5 J T–1 lies aligned with thedirection of a uniform magnetic field of 0.22 T.(a) What is the amount of work required by an external torque toturn the magnet so as to align its magnetic moment: (i) normal to the field direction, (ii) opposite to the field direction?(b) What is the torque on the magnet in cases (i) and (ii)?
Q. A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to4.5 × 10–2 J. What is the magnitude of magnetic moment of the magnet?
Q. A closely wound solenoid of 800 turns and area of cross section2.5 × 10–4 m2 carries a current of 3.0 A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic moment?
Q. A circular current carrying loop of radius r is placed in xy plane in a uniform magnetic field →B=(^i−^k)T as shown in figure, then ^i
- Potential energy of the system is negative
- Magnetic dipole moment is in the direction of positive z−axis
- Torque acting on the loop along negative y−axis
- Force experienced by the current carrying loop is zero
Q. An electric dipole consisting of two opposite charges of magnitude 2×10−6C each, separated by a distance of 3 cm is placed in an electric field of 2×105N/C. The maximum torque on the dipole will be
- 12×10–1 Nm
- 12×10–3 Nm
- 24×10–1 Nm
- 24×10–3 Nm
Q. A dipole of dipole moment 0.5 Cm ˆiis placed in an electric field 2ˆi+3ˆjNc. What is the net force and torque on the dipole?
- None of these
Q. A dipole with the magnitude of dipole moment 0.5 C-m is placed in an external uniform electric field of magnitude 10NC. →p makes an angle of 60∘ with →E. What is the potential energy of the dipole in the current configuration provided that the potential energy is taken zero when dipole is perpendicular to the applied field?
Two equal and opposite charges of 4×10−8C when placed 2×10−2cm away, form a dipole. If this dipole is placed in an external electric field of 4×108 newton/coulomb, the value of maximum torque and the work done in rotating it through 180o will be
Q. An electric dipole is situated in an electric field of uniform intensity E whose dipole moment is p and moment of inertia is I. If the dipole is displaced slightly from the equilibrium position, then the angular frequency of its oscillations is