A charge Q is distributed over three concentric spherical shells of radii a , b , c a < b < c such that their surface charge densities are equal to one another. The total potential at a point at distance r from their common centre, where r < a , would be:

Q a + b + c 4 π ϵ 0 a 2 + b 2 + c 2

Q a 2 + b 2 + c 2 4 π ϵ 0 a 3 + b 3 + c 3

Q 12 π ϵ 0 a b + b c + c a a b c

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-1>Q 207

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Two spherical conductors $A_{1}$ and $A_{2}$ of radii $r_{1}$ and $r_{2}$ are placed concentrically in air. The two are connected by a copper wire as shown in figure. Then the equivalent capacitance of the system is

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Important Questions on Electrostatics

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-1>Q 208

The dimension of

\frac{1}{2} ε_{0} E^{2}

(

ε_{0} =

permittivity of free space,

E =

electric field) is

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-1>Q 209

In an electron gun electron are accelerated through a potential difference

V

. If

e =

charge of electron and

m =

mass of electron then maximum electron velocity will be

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 1

A tiny spherical oil drop carrying a net charge

q

is balanced in still air with a vertical uniform electric field of strength

\frac{81 π}{7} \times 10^{5} V m^{- 1}

. When the field is switched off, the drop is observed to fall with terminal velocity

2 \times 10^{- 3} m s^{- 1}

. Given

g = 9.8 m s^{- 2}

, viscosity of the air

= 1.8 \times 10^{- 5} N s m^{- 2}

and the density of oil

= 900 kg m^{- 3}

, the magnitude of

q

is :

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 2

A dipole having moment $P$ is placed in front of a solid uncharged conducting sphere as shown in the diagram. The net potential at point $A$ lying on the surface of the sphere is

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 3

Two equal charges are separated by a distance

d

.

A

third charge placed on a perpendicular bisector at

x

distance from centre will experience maximum coulomb force, when

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 6

Which of the following groups do not have the same dimensions?

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 7

A spherical portion has been removed from a solid sphere having a charge distributed uniformly in its volume as shown in the figure. The electric field inside the emptied space is

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Alpha Question Bank for Medical: Physics>Chapter 22 - Electrostatics>Exercise-2>Q 8

Statement I: For practical purposes, the earth is used as a reference at zero potential in electrical circuits.

Statement II: The electrical potential of a sphere of radius $R$ with charge $Q$ uniformly distributed on the surface is given by $\frac{Q}{4 π ε_{0} R}$ .