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If W is atomic weight and N is the atomic number of an element, then

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Important Questions on Electrostatics

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Two charges of equal magnitudes and at a distance $r$ exert a force $F$ on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The charge present in a doubly ionized helium atom is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Suppose the charge of a proton and an electron differ slightly. One of them is

e

, the other is

(e + Δ e)

. If the net electrostatic force and gravitational force between two hydrogen atoms placed at a distance

d

(much greater than atomic size) apart is zero, then

Δ e

is of the order of [Given mass of hydrogen

m_{h} = 1.67 \times 10^{- 27} kg

]

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Two electrons are moving with equal speed of

5 \times 10^{5} m s^{- 1}

parallel to each other. The ratio of the electrostatic to the magnetic force between them is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The charge on one electron is :

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The acceleration of an electron due to the mutual attraction between the electron and a proton when they are

1.6 Å

apart is,

(m_{e} ≃ 9 \times 10^{- 31} kg, e = 1.6 \times 10^{- 19} C)

(Take

\frac{1}{4 π ε_{0}} = 9 \times 10^{9} N m^{2} C^{- 2}

)

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The dimensional formula of coefficient of permittivity for free space (

ε_{0}

) in the equation

F = \frac{1}{4 π ε_{0}} \frac{q_{1} q_{2}}{r^{2}},

where symbols have their usual meanings, is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Two equally charged metal spheres

A

and

B

repel each other with a force of

4 \times 10^{- 5} N

. Another identical uncharged sphere

C

is touched to

A

and then placed at the mid point of the line joining the spheres

A

and

B

. The net electric force on the sphere

C

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The attractive force results when a glass rod rubbed with a silk and a plastic rod rubbed with a fur brings together. During friction which type of charges are developed on glass rod and plastic rod?

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If two electrons are forced to come closer to each other, the potential energy of the system of

2

electrons will

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Two small metal spheres

A

and

B

charged positively are separated by

2 m

in air. The force on a charge of

+ 1 C

placed on the line joining the centres of the spheres and at a distance of

0.5 m

from

A

is found to be zero. The ratio

q_{A} : q_{B}

of charges on

A

and

B

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When a number of charged liquid drops coalesce, which of the following quantity does not change?

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Three Point charges each equal to

+ q

are placed at the vertices of an equilateral triangle of side

' l'

. The net force on a charge

q_{1}

placed at the centre of the triangle is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Two point charges A and B, having charges

+ Q

and

- Q

respectively, are placed at certain distance apart and force acting between them is

F

. If

25 %

charge of

A

is transferred to

B

, then the force between the charges becomes

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Four point charges $q_{A} = 2 μ C, q_{B} = - 5 μ C, q_{C} = 2 μ C, q_{D} = - 5 μ C$ are located at the corners of a square $A B C D$ of side $10 cm .$ The force acting on a charge of $1 μ C$ placed at centre of the square is

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Two identical conducting spheres A and B carry equal charge. They are initially separated by a distance much larger than their diameters and the force between them is F. A third identical conducting sphere C is uncharged. Sphere C is first touched to A, then to C and removed. As a result, the force between A and B now is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

Four charges each equal to

(- Q)

are placed at the four corners of a square and a charge

q

is placed at its centre. If the system of charges is in equilibrium, the value of

q

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

If a body gives out

10^{9}

electrons every second, how much time is required to get a total charge of

1 C

from it ?

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

As shown in the figure, two particles, each of mass $' m'$ tied at the ends of a light string of length $2 a$ are kept on a frictionless horizontal surface. When the mid point $(P)$ of the string is pulled vertically upwards with a small but constant force $F,$ the particles move towards each other on the surface. Magnitude of acceleration of each particle, when the separation between them becomes $2 x$ is

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Physics>Electricity and Magnetism>Electrostatics>Electrostatics

The number of electrons in one

coulomb

charge is

If W is atomic weight and N is the atomic number of an element, then

Important Questions on Electrostatics

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