List of practice Questions

A parallel plate capacitor is connected to a battery as shown in figure. Consider two situations
(i) key $K$ is kept closed and plates of capacitors are moved apart using insulating handle (ii) key $K$ is opened and plates of capacitors are moved apart using insulating handle Which of the following statements is correct?
A parallel plate capacitor with air between the plates has a capacitance of $10\, pF$. The capacitance, if the distance between the plates is reduced by half and the space between them is filled with a substance of dielectric constant $4$ is
A soap bubble is charged to a potential of $16\,V$. Its radius is then doubled. The potential of the bubble now will be :
A soap bubble is given a negative charge, then its radius
A spherical capacitor consists of two concentric spherical conductors, held in position by suitable insulating supports as shown in figure.
The capacitance $C$, of this spherical capacitor is
A test charge $q_0$ is released from rest at a distance $r$ from a source charge $q$. What will be the maximum value of the kinetic energy that may be acquired by the test charge ?
Ah electron enters an electric field with its velocity in the direction of the electric lines of force. Then
An electric dipole is along a uniform electric field: If it is deflected by $60^\circ$, work done by an agent is $2 \times 10^{-19}$ Then the work done by an agent if it is deflected by $30^0$ further is
An electric dipole of length $20 \,cm$ having $\pm 3 \times10^{-3}\,C$ charge placed at $60^{\circ}$ with respect to a uniform electric field experiences a torque of magnitude $6\, N\, m$. The potential energy of the dipole is
An electric dipole when placed in a uniform electric field will have minimum potential energy,if the angle between dipole moment and electric field is
An electron carrying charge $-e$ is located at $O$ and another charge $q$ is located at $P$. The electron is moved from $O$ to $Q$ such that $OPQ$ is an equilateral triangle. The work done in doing so is
An infinite number of charges each of magnitude q are placed-on x - axis :at distances of 1,2, 4, 8, ... meter from the origin. The intensity of the electric field at origin is
Capacity of parallel plate condenser remains unaffected on introducing a insulating slab between the plates Electric field intensity between the plates increases on introducing the insulating slab
Dielectric polarisation means formation of positive and negative charges inside the dielectric. Free electrons are formed in this process
In a series combination of capacitors, charge on each capacitor is same In such a combination, voltage across each capacitor is same
Increasing the charge on the plates of a capacitor means increasing the capacitance Capacitance is directly proportional to charge
Polar molecules have permanent dipole moment In polar molecule, the centres of positive and negative charges coincide even when there is no external field
The electric field inside a cavity is always zero Charges reside only on the outer surface of a conductor with cavity
The potential difference between the two conductors of a capacitor is small A capacitor is so configured that it confines the electric field lines within a small region of space
Work done in moving a charge between any two points in an electric field is independent of the path followed by the charge, between these points. Electrostatic force is a non conservative force.
Capacitors are used in electrical circuits where appliances need more
Consider a uniform electric field in the $z$-direction. The potential is a constant
Eight small drops, each of radius $r$ and having same charge $q$ are combined to form a big drop. The ratio between the potential of the bigger drop and the potential of the smaller drop is
Electric field due to an infinite sheet of charge having surface density $\sigma$ is E. Electric field due to an infinite conducting sheet of same surface density of charge is :
Electric field strength E due to a short dipole at a distance r from it are related as :