Proof for magnetic field due to a straight long wire at a distance r from it. ↑↓→← ⇄⇆⇅⇵
Answers
Explanation:
Right hand thumb rule If holding straight wire with right hand so that the extended thumb points in the direction of current, then curl of the fingers gives the direction of magnetic field around the straight wire.
Hy I will help you...
=> A straight line and a point constitute an unique plane. This is true for all points in three dimensional rectangular space (x,y,z). For convenience, let us consider that the point of observation (P) lies in xy plane as shown in the figure below. We can say that the straight wire along y-axis also lie in xy plane. Clearly, this plane is the plane of current length element dl and displacement vector r, which appear in the Biot-Savart expression. The direction of magnetic field is vector cross product dlX r, which is clearly perpendicular to the plane xy. This means that the magnetic field is along z-axis. This conclusion is independent of the relative positions of current length elements of the wire with respect to observation point P.