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Isha mehta

1. A charge q is distributed uniformly on a thin spherical shell. What is the electric field in the centre of the shell? If a point charge is brought close to the shell, will the field at the centre change? Does your ans depend on whether the shell is conductor or non conductor?

My answer = if it is a conductor: E at centre = zero using gauss law and the fact that the E inside a conductor = zero. If a point charge is brought close to the shell the E inside is still = zero because some rearrangement of e-s in the conductor.

Non conductor: initially filed at centre = 0 by symmetry and solid angle funda. When a point charge say q is brought close to it E changes at centre and becomes = kq/d^2.

Does anyone agree?

2. A spherical shell made of plastic contains a charge q uniformly distr. What is field inside the shell? My ans = zero. If the shell is hammered to deshape it without altering the charge, will the field inside change?

My ans = I think no. but i don't know why??????????

what happens if shell is made of a metal?

Then I know that initially the E inside = 0 and again when it is deshaped E inside still remains zero as it is a conductor.

Can some1 tell me where am I wrong?

3. A point charge q is placed in a cavity in a metal block. If charge Q is brought outside the metal will charge q feel an electric force?

My answer = due to the charge q there is an electric field in the cavity but not in the material of the block as it is a conductor. Now when a charge is brought close to it there will be some rearrangement of e-s to make E in the conductor zero and then I don't know whether the charge q in the cavity feels a force????. HELP!

4. A rubber balloon is given a charge q uniformly distributed on its surface . is the field inside the balloon zero everywhere if it is not spherical?

i think that E inside the balloon = 0 but don't the reason y??

what if it is an oval balloon?

Q.59 HCV elec field - an electric field E = Axi exists in space A = 10 V/m^2 take the V at (10,20) to be zero. Find pot. At origin.

Ans = 500V

pratham maheshwari

the first question is right but there is mistake in concept.....ie. the field inside the conductor is zero means that a charge (say q)when embedded in the conductor faces zero electric field(net electric field due to all charges) but that doesnot harm your ans bcoz in cavity E=0 for all case, (except when charge is not inside cavity)

pratham maheshwari

second ques. the according to me the ans should be no it will change(correct me if i am wrong) DRAW A GAUSSIAN SURFACE AROUN THE CHARGE

q enclosed=0 so E=0
bcoz the object does not remain symmetrical......
as for conductor yes it will b zero bcoz inside cavity E=0(except when charge is not inside cavity)

pratham maheshwari

no, for the third question bcoz charge distribution takes place on the metal surface.....

Isha mehta

i'm waiting for the experts....

ashwin sridhar

while u wait here's my answer.

1) electric field anywhere inside a spherical shell(whether cond or non cond) is 0

Shell theorem

if pt charge is brought close to the shell- field changes at the centre if non conductor. remains 0 if metal.

as far as field goes the exp kq/d^2 is same but value of k is not 1/4

_o

2) field inside shell again 0

field inside deshaped shell 0 if metal

non 0 if plastic(hence field changes)

3) NEVER

4)nope if the baloon is not sperical there will be a field inside

5) use the formula V= -_{[ 10]}^{[ 0]}Edx . if u didnt get it i'll show the steps if u want

Bipin Dubey

Electrics field at the centre would be 0. If we draw a small Gaussian surface around the centre, the charge enclosed is zero and hence the electric field is zero.

If we bring a point charge close to the shell then also the field will be 0.

Non-conducting means that the charge stays in place.A conducting shell would have had charges which were free to move within the shell. In both the cases field would be be zero at the centre.

Please post your other queries on a new page.

Isha mehta

Deepak Aggarwal

1. Electric field at the center of shell is zero (sice charge enclosed is zero). If a charge is brought to close to the shell, field at center still remains zero. This was the case of conducting. But if the shell is non-conducting it is non-zero.

2. zero........When it is deshaped still the field remains zero only (use gauss's law).

3. No, basically bcoz the charge distribution takes place on the surface.

4. If the balloon is spherical field field inside would be zero even if it is not spherical but oval.

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