In the product

$$\overrightarrow F = q\left( {\overrightarrow v \times \overrightarrow B } \right)$$

$$ = q\overrightarrow v \times \left( {B\widehat i + B\widehat j + {B_0}\widehat k} \right)$$

For q = 1 and $$\overrightarrow v = 2\widehat i + 4\widehat j + 6\widehat k$$ and $$\overrightarrow F = 4\widehat i - 20\widehat j + 12\widehat k$$

What will be the complete expression for $$\overrightarrow B $$ ?

A uniform conducting wire of length 12a and resistance 'R' is wound up as a current carrying coil in the shape of ,

(i) an equilateral tringle of side 'a'

(ii) A square of side 'a'

The magnetic dipole moments of the coil in each case respectively are :

An iron rod of susceptibility 599 is subjected to a magnetizing field of 1200 A m^-1. The permeability of the material of the rod is :
$$\left( {{\mu _0} = 4\pi \times {{10}^{ - 7}}Tm{A^{ - 1}}} \right)$$

At a point A on the earth’s surface the angle of dip, $$\delta $$ = + 25^o. At a point B on the earth's surface the angle of dip, $$\delta $$ = – 25^o. We can interpret that :