IIT JEE , AIEEE Forum - Physics , Electricity - Electric Field due to thin infinite sheet

its_ankit007

Hi, in many books i have seen that they give two derivations/formulae for electric field of thin infinite uniformly charged plane sheet- one for one sided charged:

/2

₀ and one for two sided charged:

/

₀ (

being the charge density). I don't understand what is the meaning of one sided and two sided charged? Besides, is there anything like two-sided charged? Pls reply.

iam_quantized

U CAN SAY THAT THE 2ND EXPRESSION IS THE ELECTRIC FIELD BETWEEN TWO OPPOSITE CHARDED PLATES EXAMPLE INSIDE A PARRALLEL PLATE CAPACITOR N 1ST 1 IS FOR A SINGLE PLATE

jatinpreet

The electric feild at (or very near to ) the surface of an conductor is give as

/

its_ankit007

@ jatinpreet
I dont understand wat is the meaning of "at (or very near to )" . The electric field lines emerge out of the plane sheet prependicularly and the field thus, is contant everywhere.

prakhar_galaxy

Hey ankit there is no need of any confussion on this.The 1st formula i.e

/2

is used when the plate is very very thin(i.e its thickness is almost negligible). But for a thick plate we cannot ignore its thickness thus we consider it as a combination of two very thin plates and thus the resultant answer is

/

I am very sure of my answer but if you have any doubts you can ask it .

You can get them easily in books like RESHNICK HALLIDAY ,H.C VERMA OR P.PRAKASHAN.

deepak_agarwal

good question...this ques i believe all students preparing for jee asks.....see first ans comes directly from gauss law...right???now the second part

/

is the electric field of a CONDUCTOR at any point infinetly close to the surface...now what is a conductror???a body with charge uniformly distributed through out..that ans y thereis charge on both the sides....secondlt it is not valid only for plate but for any conductor bt at a point really close....

TIP:second formula is rarely used..1 in 1000 times so if u r confused its a safe bet to go with the first one.....

vinod

well u see the explanation given in resnic and halliday is not that clear, read the book "lectures on physics"- by Richard. Feynman.
he giv's it like this

in a conducting metal plate charges are spread on both sides equally, so electric field at each side is given by ?/2? 0---(1) (according to gauss law?E.F due to non conducting insulator plate has charge on one side only?check in resnic and halliday) ---so for total :- ?/? 0, for a cap'r since the opp charged plates are kept close together charge only exist on one side. Therefore E.F is
same as (1) i.e ?/2? for each plate on one side . thus total E.F due to cap?r is
?/2? 0 + ?/2? 0 = ?/? 0 ??

H.C Verma is also has simplified explanation than "lectures on physics"....

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