EASY
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A total charge Q is distributed uniformly along a straight rod of length 1. The potential at a point P at a distance h from the midpoint of the rod is

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Important Questions on Gauss's law and Its Application

HARD
106 conducting droplets of radius 10-6 m each and each having an electrical charge of 2×10-14C, are merged together to form a single drop. If the droplets were initially far apart, how much work is done in assembling the single drop?
HARD
A uniformly charged ring of radius 3a and total charge q is placed in xy plane centred at origin. A point charge q is moving towards the ring along the z- axis and has speed v at  z=4a . The minimum value of v such that it crosses the origin is:
HARD
A charge +q is distributed over a thin ring of radius r with line charge density λ=qsin2θπr. Note that the ring is in the XY-plane and θ is the angle made by r with the X-axis. The work done by the electric force in displacing a point charge +Q from the centre of the ring to infinity is
HARD
27 similar drops of mercury are maintained at 10 V each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is ___________ times that of a smaller drop.
MEDIUM
Two equal point charges are fixed at x=-a and x=+a on the x -axis. Another point charge Q is placed at the origin. The change in the electrical potential energy of Q , when it is displaced by a small distance x along the x -axis, is approximately proportional to
MEDIUM
A charge Q is given to a spherical shell of radius R. The work done to distribute the charge Q on the surface of the sphere is
HARD
Calculate the minimum value of v, with which q should be projected so that, it just reaches the centre of the ring.

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HARD
A small positively charged ball of mass m is suspended by an insulating thread of negligible mass. Another positively charged small ball is moved very slowly from a large distance, until it is in the original position of the first ball. As a result, the first ball rises by h. How much work has been done?
EASY
On moving a charge of20 Coulomb by 2 cm, 2 J of work is done, then the potential difference between the points is
HARD
A metal sphere of radius 0.1 m was insulated from its surroundings and given a large positive charge. A small charge was brought from a distance point to a point 0.5 m from the sphere's centre. The work done against the electric field was W and the force on the small charge at its final position was F. If the small charge has been moved to only 1 m from the centre of the sphere, what would have been the values for the work done and the force?
MEDIUM
Charges +q & -q are placed at points A & B respectively which are a distance 2L apart, C is the mid-point between A & B. The work done in moving a charge Q along the semicircle CRD is


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EASY

Three charges Q0, -q and q are placed at the vertices of an isosceles right angle triangle as in the figure. The net electrostatic potential energy is zero if Q0 is equal to

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MEDIUM
Two identical charges are placed at the two corners of an equilateral triangle. The potential energy of the system is U . The work done in bringing an identical charge from infinity to the third vertex is
HARD
Four charged particles (A, B, C, D) of mass m and charge q each, are connected by light silk threads of length d forming a tetrahedron floating in outer space. The thread connecting particles A and B suddenly snaps. Find the maximum speed of particle A after that -
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HARD
A system consists of two thin concentric metallic shells of radii R1 and R2 R1>R2 with corresponding charges q1 and q2 . The total electric energy of the system is
MEDIUM
The work required to put the four charges at the corners of a square of side a, as shown in figure, is

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MEDIUM
A charge Q is given to a spherical shell of radius R , the work done to distribute charge Q on the surface of sphere is -
MEDIUM
1000 similarly electrified raindrops merge together into one drop so that their total charge remains unchanged. How is the electrical energy affected?
MEDIUM
Three charges 1 μC, 2 μC, 3 μC are kept at the vertices of an equilateral triangle of side 1 m. If they are brought nearer so that, they now form an equilateral triangle of side 0.5 m, then work done is
MEDIUM
If an electron is brought towards another electron, the electric potential energy of the system