But since areas differ by a factor of 4, the effective ratio simplifies to 2 : 1.
Advertisements
Advertisements
Question
A point charge is placed at the centre of a hollow conducting sphere of internal radius ‘r’ and outer radius ‘2r’. The ratio of the surface charge density of the inner surface to that of the outer surface will be ______.
Advertisements
Solution
A point charge is placed at the centre of a hollow conducting sphere of internal radius ‘r’ and outer radius ‘2r’. The ratio of the surface charge density of the inner surface to that of the outer surface will be 2 : 1.
Explanation:
When a point charge is placed at the centre of a hollow conducting sphere, an equal and opposite charge is induced on the inner and outer surfaces.
Since surface charge density (σ) = `Q/(4 pi R^2)`, it is inversely proportional to the square of radius.
Inner radius = r
Outer radius = 2r
`sigma_"inner" : sigma_"outer" = 1/r^2 : 1/((2 r)^2)`
= 4 : 1
RELATED QUESTIONS
If Coulomb’s law involved 1/r3 dependence (instead of 1/r2), would Gauss’s law be still true?
A 12 pF capacitor is connected to a 50 V battery. How much electrostatic energy is stored in the capacitor? If another capacitor of 6 pF is connected in series with it with the same battery connected across the combination, find the charge stored and potential difference across each capacitor.
If R is the radius of a spherical conductor, Vm the dielectric strength, then the maximum electric-field magnitude to which it can be raised is ______.
A test charge q is made to move in the electric field of a point charge Q along two different closed paths (Figure). First path has sections along and perpendicular to lines of electric field. Second path is a rectangular loop of the same area as the first loop. How does the work done compare in the two cases?

Consider a finite insulated, uncharged conductor placed near a finite positively charged conductor. The uncharged body must have a potential:
A thin spherical shell is charged by some source. The potential difference between the two points C and P (in V) shown in the figure is:
(Take `1/(4 pi epsilon_0` = 9 × 109 SI units)

What does \(\varepsilon_0\) represent in the electric-field formula for a charged conductor surface?
How does an empty cavity inside a conductor relate to electrostatic shielding?
For the Gaussian pillbox at a charged conductor's surface, from which face does the flux come?
Which potential–field relation is used to show that potential is constant inside a conductor?
