EXERCISE 7

Does a magnetic monopole exist?

What are poles of a magnet? How they have got their specific names?

Earth's magnetic field may be imagined to be due to a small bar magnet located at the centre of the earth. If the magnetic field at a point on the magnetic equator is $0.3\times {10}^{-4} \mathrm{T},$ what is the moment of such a bar magnet? What is the value of the magnetic field at the north pole? (radius of the earth$=6.4\times {10}^6 \mathrm{m}$)

Find the magnetic moment of the magnet if the earth's horizontal magnetic field is $20\mu \mathrm{T}.$

The needle of a deflection magnetometer deflects through $45°$ from north-south when the instrument is used in Tan-A position with a magnet of length $8 \mathrm{cm}$ placed at a distance of $20 \mathrm{cm}$

A short bar magnet placed with its axis at $30°$ to a uniform magnetic field of $0.2 \mathrm{T}$ experiences a torque of $0.06 \mathrm{N}.\mathrm{m}.$

Calculate the magnetic moment of the magnet and

A magnetic needle has magnetic moment undefined and moment of inertia $I=7.5\times {10}^{-6}{\mathrm{kgm}}^2.$ It performs $10$ complete oscillations in $6.70 \mathrm{s}.$ What is the magnitude of the magnetic field ? $\left[B=9.8\times {10}^{-5} \mathrm{T}\right]$

A dip circle is set at ${45}^{\circ }$ to the magnetic meridian, then the apparent dip is ${30}^{\circ }$ Calculate the true dip.

If a magnet is cut into four equal parts such that their length and breadths are equal. Pole strength of each part is