EASY
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A ring of radius R with a uniformly distributed charge q is shown in figure. A charge q0is now placed at the centre of the ring. Find the increment in the tension in ring.

Important Questions on Electrostatics

MEDIUM
A simple pendulum of length L is placed between the plates of a parallel plate capacitor having electric field  E , as shown in figure. Its bob has mass m and charge  q . The time period of the pendulum is given by:
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MEDIUM
Two parallel infinite line charges with linear charge densities +λ C m-1 and -λ C m-1 are placed at a distance of 2R in free space. What is the electric field mid-way between the two-line charges?
HARD
Four point charges -q, +q, +q and -q are placed on y-axis at y=-2d, y=-d, and y=+2d, respectively. The magnitude of the electric field E at a point on the x-axis at x=D, with Dd, will behave as:
HARD
Consider a sphere of radius R which carries a uniform charge density ρ . If a sphere of radius R2 is carved out of it, as shown, the ratio EAEB of magnitude of electric field EA and EB , respectively, at points A and B due to the remaining portion is:

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EASY
The electric field in a certain region is acting radially outward and is given by E=Ar. A charge contained in a sphere of radius a centred at the origin of the field will be given by
HARD

Three charged particles AB and C with charges -4q,2q and -2q are present on the circumference of a circle of radius d. The charged particles A,C and centre O of the circle formed an equilateral triangle as shown in the figure. The electric field at the point O is
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EASY
The bob of a simple pendulum has mass 2 g and a charge of 5.0 μC. It is at rest in a uniform horizontal electric field of intensity 2000 V/m At equilibrium, the angle that the pendulum makes with the vertical is:
takeg=10 m/s2
HARD

A charged particle (mass m and charge q) moves along X axis with velocity V0. When it passes through the origin it enters a region having uniform electric field E=-Ej^ which extends upto x=d. Equation of path of electron in the region x>d is:

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EASY
A charged particle initially at rest at O, when released follows a trajectory as shown. Such a trajectory is possible in the presence of
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MEDIUM
An electric field due to a positively charged long straight wire at a distance r from it is proportional to r-1 in magnitude. Two electrons are orbiting such a long straight wire in circular orbits of radii 1 A and 2 A. The ratio of their respective time periods is
HARD
A thin spherical insulating shell of radius R carries a uniformly distributed charge such that the potential at its surface is V0. A hole with a small area α4πR2α1 is made on the shell without affecting the rest of the shell. Which one of the following statements is correct?
HARD
A particle, of mass 10-3 kg and charge 1.0 C, is initially at rest. At time t=0, the particle comes under the influence of an electric field Et=E0sinωt i^, where E0=1.0 N C-1 and ω=103 rad s-1. Consider the effect of only the electrical force on the particle. Then the maximum speed, in m s-1, attained by the particle at subsequent times is ____________.
MEDIUM
A particle of mass m and charge q is placed at rest in uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is
HARD
A particle of mass m and charge q is released from rest in a uniform electric field. If there is no other force on the particle, the dependence of its speed v on the distance x travelled by it is correctly given by (graphs are schematic and not drawn to scale)
EASY
Two charged thin infinite plane sheets of uniform charge density σ+ and σ-, where σ+>σ, intersect at the right angle. Which of the following best represents the electric field lines for the system:
MEDIUM
Suppose that intensity of a laser is 315π W m-2. The rms electric field, in units of V m-1 associated with this source is close to the nearest integer is -ε0=8.86×10-12 C2 N m-2; c=3×108 m s-1
EASY

Charges Q1 and Q2 are at points A and B of a right-angled triangle OAB. The resultant electric field at point O is perpendicular to the hypotenuse, then Q1/Q2 is proportional to:

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MEDIUM
Charges Q, 2Q and 4Q are uniformly distributed in three dielectric solid spheres 1, 2 and 3 of radii R/2, R and 2R respectively, as shown in the figure. If magnitudes of the electric fields at point P at a distance R from the centre of spheres 1, 2 and 3 are E1,  E2 and E3 respectively, then

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HARD
A wire of length L=20 cm is bent into a semi-circular arc and the two equal halves of the arc are uniformly charged with charges +Q and -Q as shown in the figure. The magnitude of the charge on each half is Q=103ε0, where ε0 is the permittivity of free the space. The net electric field at the centre O is

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MEDIUM
Two point charges q110 μC and q2-25 μC are placed on the x -axis at x=1 m and x=4 m respectively. The electric field in V m-1 at a point y=3 m on y-axis is,

Take 14πϵ0=9×109 N m2C-2