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in this video I will talk about an
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application of gau's law which is
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derivation of gum's law from G's law now
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when we start studying electrostatic
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first and very fundamental law we came
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across this pums law from this kums law
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we introduce the concept of electric
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field and deriv the guses law now
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reverse of this is also possible which
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means that kum's law can be derived from
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from gs's law by using gs's law to
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obtain the expression for finding the
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electric field due to point
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charge now to do this first consider the
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electric field due to a single isolated
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positive Point charge Q as shown in this
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figure by symmetry field of this
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isolated positive charge Q is radially
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outwards everywhere and magnitude of
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electric field intensity is same for all
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charge next we can imagine cion surface
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to be a sphere of radius are enclosing
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Q now from gs's law integral e do da is
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= to e integral da which is equals to
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enclosed upon Epson not now here note
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that this circle on the integral sign
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reminds us that the integral is always
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taken over the closed surface in closing
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the charge Q now since electric field e
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is constant at all points of the surface
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so we have e a = to Q upon Epsilon
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now surface area of a sphere is given as
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a = 4 Pi r² so electric field e is equal
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to 1 upon 4 pson q upon
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r² now if we put a point charge
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containing q- amount of charge at a
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distance are from this point charge
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having charge Q then force on q- Q to
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charge Q would be f = q- e or Force f =
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1 upon 4 pepson qq- upon r² this is
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nothing but the kum's
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law so for more notes and study material
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regarding this topic please visit our
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website physics catalyst.com
