Electric field at a point in the space around a system of charges tells us the force a unit positive
test charge would experience if placed at that point (without disturbing the system). Electric field is a characteristic of the system of charges and is independent of the test charge that we place at a point to determine the field. The term field in physics generally refers to a quantity that is defined at every point in space and may vary from point to point. Electric field is a vector field, since force is a vector quantity. consider the force between two distant charges q1, q2 in accelerated motion. Now the greatest speed with which a signal or information can go from one point to another is c, the speed of light. Thus, the effect of any motion of q1 on q2 can not arise instantaneously. There will be some time delay between the effect (force on q ) and the cause (motion of q ). arise instantaneously. There will be some time delay between the effect (force on q2) and the cause (motion of q1). The accelerated motion of charge q1 produces electromagnetic waves, which then propagate with the speed c, reach q2 and cause a force on q2. Thus, even though electric and magnetic fields can be detected only by their effects (forces) on charges, they are regarded as physical entities, not merely mathematical constructs.
2 comments:
It is not necessary that when we move q1, only then q2 is effected. If we place q2 very close to q1 then it will experience force due to electric field.Now my question is that if we place these charges a far apart then would they experience force? If not then why because electromagnetic waves can go a far apart.
USE S=E*H BUT E IS PROPORTIONAL TO 1/r
WE MOVE CHARGES APART E DECREASES AND ALSO S DECREASES
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