Two nonconducting plates A and B of radii 2R and 4R, respectively, are kept at distance x and 2x from the point charge q. A surface cutout of a nonconducting shell A is kept such that is center coincides with the point charge. Each plate and spherical surface carries surface charge density sigma. If distance x and radius R are doubled so that F_A becomes F'A,F_B becomes F'B, then the correct option is

Two nonconducting plates A and B of radii 2R and 4R, respectively, are

1.	Two nonconducting plates A and B of radii 2R and 4R, respectively, are kept at distance x and 2x from the point charge q. A surface cutout of a nonconducting shell A is kept such that is center coincides with the point charge. Each plate and spherical surface carries surface charge density sigma. If distance x and radius R are doubled so that F_A becomes F'A,F_B becomes F'B, then the correct option is
Answer» `F_BgtF'_B` `F'_BgtF_B` `F'_AgtF'_B` none of these Solution :For A and B we know that Flux `=phi=intE.ds` Force `=intsigmaE.ds=sigmaintE.ds=sigmaphi` As flux DUE to charge Q in each plate is same force will be same. For C we have taken the HORIZONTAL component of electric field , but for As force due to one plate on another plate is same, hence `phi` due to 1 in another and due to 2 in 1 will be same. When x and R increased `phi` in plate due to charge remains same, hence force due to charge on plates does not CHANGE.

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