electrostat graph...................

18 Answers

1
Manmay kumar Mohanty ·

yes if u have an arihant book check it out.

1
rahul nair ·

but its given tht the charge is distributed uniformly throughout the sphere,

so the sphere should be non conducting..........

1
abcd ·

@ rahul if it is a conducting sphere then the charges will be repelled and will get arranged on the periphery!

1
rahul nair ·

@ Ishan, ques indicates tht
sphere is charged uniformly throughout the volume of the sphere.Then how can electric field at an internal point be 0?

1
abcd ·

answer is b (taking the sphereto be conducting)

explaination:

we know that the electric field inside a sphere is zero (shell law which is basically to satisfy the electrostat condition) hence the potential will be constant for r'=0 to r'=r (where r is the radius)

now once we r outside the sphere ,the charge can be considered to be concentrated at the centre of the sphere by spherical symmetry hence it will vary inversely with the square of distance from the centre

graph of a constant function is a straight line parallel to x axis (...i.e when r'<=r)

graph of 1/x2 is a rectangular hyperbola restricted in the first quadrant

join these two and the answer..i.e (B) becomes evident!!

11
SANDIPAN CHAKRABORTY ·

the ans would had been b if it was a hollow sphere the first line says it is a solid sphere

11
SANDIPAN CHAKRABORTY ·

take k=1/4(pi)eo
The electric field intensityoutside the sphere is :
Eoutside=k q/r2
dVoutsidedr = -Eoutside
or
\int_{\propto }^{V}{dVoutside} = - \int_{\propto }^{r}{kq/r2} dr

or V = kq/r as V\propto = 0

or V \propto 1/r

At r=R V=kq/R

i.e at the surface of the sphere potential is Vs = kq/R

The electric intensity inside the sphere ,
Einside = k q r/R3

dVinsidedr = - Einside

or \int_{Vs}^{V}{dVinside} = -kqR3\int_{R}^{r}{r dr}

so V - Vs = - kqR3[r22]rR

substituting Vs = kqR(32 - r22R2)

At center r=0 & Vc = (3/2)(kq/R) = 1.5 Vs

i.e. the potential at the center is 1.5 times the potential at the surface

graph will be as my previous post...........

1
Manmay kumar Mohanty ·

Eoutside = \frac{1}{4\pi \varepsilon _{0}} \frac{q}{r^{2}} \frac{dV_{outside}}{dr} = - E_{outside} \int_{infinite}^{V}{dV_{outside}} = - \int_{infinite}^{r}{\frac{1}{4\pi \varepsilon _{0}} \frac{q}{r^{2}} }dr V = \frac{1}{4\pi \varepsilon _{0}} \frac{q}{R} at r = R E_{inside} = \frac{1}{4\pi \varepsilon _{0}} .\frac{q}{R^{3}}.r \frac{dV_{inside}}{dr} = - E_{inside} \int_{V_{s}}^{V}{dV_{inside}}= - \frac{1}{4\pi \varepsilon _{0}}\frac{q}{R^{3}}\int_{R}^{r}{r}dr where Vs is potential at surface = \frac{1}{4\pi \varepsilon _{0}} \frac{q}{R}

V - Vs = - \frac{1}{4\pi \varepsilon _{0}} \frac{q}{R^{3}}[\frac{r^{2}}{2}] with integration limits R to r

Substituting Vs, we get V = \frac{1}{4\pi \varepsilon _{0}} \frac{q}{R}\left[\frac{3}{2} - \frac{1}{2}\frac{r^{2}}{R^{2}}] \right

GOT THAT !!!!!

1
sumit_kumar ·

no i dont hav arihant , plzzzzzz post that derivation

1
hacker ·

well assuming sphere is positively charged!!![3]
and should be a

1
sumit_kumar ·

in the soln i hav , the hint given is that V= k Q(3R2-r2)2R3

HOW HAS THIS BEEN DERIVED???????

11
SANDIPAN CHAKRABORTY ·

saw in arihant ans c

the graph is

1
sumit_kumar ·

didnt get msp .....why will the sphere be a nonconductor?

1
Manmay kumar Mohanty ·

So if it is so ans is C)

3
msp ·

charged uniformly means dat the sphere is a nonconductor.

1
Manmay kumar Mohanty ·

1
rahul nair ·

c.

1
Manmay kumar Mohanty ·

is it b)

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