The magnetic needle of a tangent galvanometer is deflected at an angle $30$ due to a magnet. The horizontal component of the earth's magnetic field$0.34\times {10}^{-4}T$ is along the plane of the coil. The magnetic intensity is:

Q. A tangent galvanometer has a coil with $50$ turns and radius equal to $4$ cm. A current of $0.1$ Amp is passing through it. The plane of the coil is set parallel to the earth's magnetic meridian. If the value of the earth's horizontal component of the magnetic field is $7\times {10}^{-5}T$ and ${\mu }_0=4\pi \times {10}^{-7}Wb/A-m$. then the deflection in the galvanometer needle will be :

Q. The horizontal component of earth's magnetic field is $0.4\times {10}^{-4}T$ and the angle of dip is ${30}^{\circ }$. Calculate the value of
(i) vertical component
(ii) the total intensity of the earth's magnetic field.

Q. The radius of each coil of a Helmholtz galvanometer is $0.1m$ and number of turns in each is $25$. When a current is passed in it then the deflection of magnetic needle observed as ${45}^o$. If the horizontal component of earth's magnetic field is $0.314\times {10}^{-4}T$ then the value of current will be

Q. A compass needle is free to turn in a horizontal plane is placed at the centre of a circular coil of $30$ turns and radius $12\text{cm}$. The coil is in a vertical plane, making an angle of ${45}^{\circ }$ with the magnetic meridian. When the current in the coil is $0.35\text{A}$, the needle points west to east. Find the horizontal component of the earth's magnetic field at the location.