The charged currents in the outer conducting regions of the earth's core are thought to be responsible for earth's magnetism. What might be the battery' (i.e., the source of energy) to sustain these currents?

I ampere current is flowing through a l metre long conducting . If the wire is shaped into a circular loop, then what will be its magnetic moment ?

If the current through a conducting loop in the shape of an equilaterla triangle of side a be I, what will be the magnitude of the magnetic field of intersection of the three medians ?

A circular coil of N turns is made of a conducting wire of a certain length . When a current I is sent through it , the magnetic moment is p , Another coil of 2N turns is made with the same wire and the same current is sent through it . The magnetic moment becomes p'. If p : p ' = n : 1 , what is the value of n ?

If a current passes through a metal conducting wire of area of cross section A, the drift velocity of free electrons inside the metal is v_d=1/( n e A) , where the amount of electric charge of an electron =e and the number of free electrons per unit volume of the metal=n. The applied electric field on the wire is E=V/l , where a potential difference V exists between two points, l apart, along the length of the wire. IF R is the resistance of the wire between those two points, then the resistivity of its material is rho=(RA)/l .Besides the mobility (mu) of the free electrons inside a wire is defined as their drift velocity for a unit applied electric field. Two copper wires have both lengths and radii in the ratio 1:2 if the ratio between the electric currents flowing through them is also 1:2 , what would be the ratio between the drift velocities of free electrons?

A wire is kept horizontally at a place in the northern hemisphere of the earth . In what direction will force act on the wire due to the vertical component of the earth's magnetic field , if electric current flows through the wire from south to north ?

The earth's surface has a negative surface charge density of 10^-9C.m^-2 . The potential difference of 400kV between the top of the atmosphere and the surface results (due to the low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there wre no mechanism of sustaining atmospheric,electric field, how much time (roughly) would be required to neutralise earth's surface? [Radius of earth = 6.37 times 10^6m ]

A short bar magnet placed on a horizontal plane has its axis aligned along the magnetic north- south direction . Null points are found on the magnet . The earth's magnetic field at the place is 0.36G . What is the magnet at the total magnetic field on the normal bisector of the same distance as the null points (i.e., 14 cm) from the centre of the magnet (at null points , field due to a magnet is equal and opposite to the horizontal component of earth's magnetic field . )

A parallel plate capacitor is made out of two rectangular metal plates of sides 30 cm x 15 cm separated by a distance of 2 mm. The capacitor is charged in such a way that the charging current has a constant value of 100 mA. What must be the rate of change of potential of the charging source and what will be the displacement current in the region between the capacitor plates?

The Earth's surface has a negative surface charge density of 10^(-9)C//m^2 . The potential difference of 400kV between the top of the atmosphere and the surface, results (due to low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there is no mechanism of sustaining atmospheric electric field, how much time (roughly) would be required to neutralise the Earth’s surface?