the electric flux along the electric line of force is...... imcerese decrese
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Electrical Charges could be positive or negative. Thus electrical forces could be attractive or repulsive. Some agreed upon conventions have been arrived at so that we all speak the same language.
Electric Fields have lines that travel from a positive charge to a negative charge (call these two charges’ base charges’), the direction of their travel being shown using an arrow. These arrows indicate the direction of Coulomb Force that another positive charge q would experience if it were to be located at any point in the electric field.
Let us look closer at that ‘other charge’. We will use it as a ‘Test Charge’. Let it have a very very tiny magnitude q, much smaller than 1 coulomb. We keep it minuscule so that it doesn’t distort the very field it is used to probe.
Suppose we let loose this tiny test charge of q Coulombs at any point on one of the field lines shown in the sketch above, by Coulomb’s Law, it will obviously get pushed away by the positive base charge and get pulled towards the negative base , and will, therefore, spontaneously travel along the field line, in the same direction as the arrow.
Let us now understand what is Electrical Potential.
Let us imagine this positive test charge being brought towards the field illustrated above from an infinite distance. At a distance equal to infinity, the forces exerted on the test charge by our two base charges would be zero. F ∝ 1r2 where r=∞ .
As the test charge comes closer to the field, the positive base charge would oppose such motion since like charges repel one another. We would, therefore, have to expend effort, or perform work in order to bring the test charge closer to it. The test charge would, therefore, be acquiring more and more potential energy as it comes closer to the positive base charge.
On the other hand, moving the test charge towards the negative base charge would be simpler, since the test charge would be attracted towards it, and it would tend to move towards it spontaneously, like a ball rolling downhill. The test charge would, therefore, be losing potential energy as it moves closer to the negative charge.
It was Faraday who proposed a revolutionary change to our way of thinking about such problems, and introduced the ‘Theory of Fields’.
Instead of thinking in terms of the potential energy that may get acquired or expended by a charge in its peregrinations in the field, let us compute and ascribe a value to each ‘point in the field’, equal to the potential energy that WOULD HYPOTHETICALLY BE ACQUIRED by a HYPOTHETICAL UNIT CHARGE, were it perchance, to be located at that point.
I use the word ‘UNIT’ charge with trepidation. Technically that would mean 1 Coulomb, which is such a huge charge it would completely mess up the field.
So we use the trick of making Test Charge q really, really small - perhaps nano nano nano …Coulomb. We compute the Potential Energy U Joules that would be acquired by the test charge when brought to point P from a distance = ∞ , and then then establish Uq . This will give us the Electric Potential of point P in volts.
Field theory, thus, requires that we stop thinking ‘Electrical Potential Energy acquired by a Charge’ that is moving around, and start thinking ‘Electrical Potential’ of every fixed point in an Electric Field. A simple but profound paradigm change.
The arrows on our electric field lines, therefore, provide us the direction from a point with higher potential, to a point of lower potential.
hope this will help u to understand this topic deeply................