IIT JEE , AIEEE Forum - Physics , Electricity - earn a salute who gives me a satisfied answer.

manmadha

Two concentric spherical spheres of radii a & b (b>a) having charges q & Q respectively, then what is the charge on inner side of sphere of radius b ? explain.

kusum

hi,
the inner side of the radius b would be -q if the shells are made of conducting material .i guess even otherwise its true

rohitju

r u sure tere r 2 concentric spheres.not shells?

manmadha

they r hollow spheres (sheel) & kusum i need an explanation

sagarbhale

well manmadha or whatever state the question better

if they are solid spheres then one sphere will be part of another and if they r of conducting material then the total charge will get nullified

if they are shells separated by vaccume then there are further possibilities

if the thickness of shells is considered then what kusum says is correct.
if the shells are made out of positively charged particles only and have negligible thickness...then the charge on inner surface of b will be +Q only

sagarbhale

as far as kusums solution is considered....she has considered that the shperes have a thickness

thus if the outer part of sphere has positive charge and even inside the bigger shpere there is a positively charged surface then the inner surface of the bigger sphere is bound to have -Q charge due to induction...the positive surface inside B will attract all the electrons towards the inward surface....

manmadha

i know dat it attracts ,but why it is only -q which appears on innerpart of sphere?

kusum

hi,
the concept behind the prob is inside a conducting material electric field is always zero so u can take net charge to be zero .

keepin the smae in mind,
the inner surface of the shell will have zero charge ,
its outer surface q

outer shellll inner surace -q to make net charge zero inside it
its outer surface q+q to maintain chrage constant

.i hope im clear

manmadha

yes kusum,but here electric field is not zero inside outer shell because there is another shell inside.i.e there is Electric field between a & b

kusum

hi ,
just check the net charge apply gauss law E=Q0 / epsilon0

sagarbhale

manmadha,
+Q and -Q must add up to give 0 total charge
if B has uniform charge +Q spread across its outer surface then it has to have -Q charge on its inner surface as there is no other surface for electrons to go

and as the sphere inside B also has uniform positive charge across its surface it will attract all the -Q charge developed on the inner surface of B uniformly

are you getting me??

kusum

hi ,
mamadha y dont u check HC VERMA FOR GAUSS LAW APPLICTION
then within no time u'lll undersand my slon

manmadha

yes the net charge will be q if gaussian surface is jus inside the outer shell

manmadha

actuaaly the ques,. is a part of example-3 page-137 in HCV

Ask & Discuss Questions with Community & Experts