//Ex:1.43
clc;
clear;
close;
printf("Retarded vector potential- The vector potential expression represents the super positions of various current elements I.dl, at a distant point P at a distance of r. If these are simply added up, it means an assumption is made that these field effects which are super imposed at time t, all started from the current elements of the same value of current and even though they have travelled different. Varying distances in other words finite time of propagation has been ignored which is not correct. This would have been correct provided the velocity of propagation would have been infinite which is actually not.");
printf("\n If the expression for vector potential in Integrated it follows thet potential due to various current element are added up let us suppose that current (I) is istantaneous current (I) in the element be Sinusoidal function of time as");
printf("\n I=Im.sin(wt), where Im= max current");
printf("\n I=Instantaneous current");
printf("\n w=2hf, angular frequency");