A charge Q is placed at the origin. The electric potential due to this charge at a given point in space is V. The work done by an external force in bringing another charge q from infinity up to the point is
(a) v/q
(b) vq
(c) v+q
(d) v
If 100 J of work has to be done in moving an electric charge of 4 C from a place, where potential is -10 volt to another place where potential is V volt,find the value of V.
(a) 5 V
(b) 10 V
(c) 25 V
(d) 15 V
The electric potential due to point charge 3 nC at distance of 9 cm is
(a) 270 v
(b) 3 v
(c) 300 v
(d) 30 v
In a region of constant potential,
(a) the electric field is uniform
(b) the electric field is zero
(c) there can be no charge inside the region
(d) the electric field shall necessarily change, if a charge is placed outside the region
Three capacitors 3 μF, 6 μF and 6 μF are connected in series to a source of 120 volt. The potential difference across the 3 μF capacitor will be
(a) 40 volt
(b) 30 volt
(c) 40 volt
(d) 60 volt
Equipotential surfaces at a great distance from a collection of charges whose total sum is not zero are approximately
(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids
The electrostatic potential energy between proton and electron separated by a distance of 1 Å is
(a) 13.6eV
(b) 27.2eV
(c) -14.4eV
(d) 1.44eV
The electric potential of earth is taken to be zero, because earth is a good
(a) insulator
(b) conductor
(c) semiconductor
(d) dielectric
An air capacitor is charged with an amount of charge q and dipped into an oil tank. If the oil is pumped out, the electric field between the plates of capacitor will
(a) increase
(b) decrease
(c) remain the same
(d) becomes zero
A parallel plate air capacitor has a capacitance 18μF. If the distance between the plates is tripled and a dielectric medium is introduced, the capacitance becomes 72μF. The dielectric constant of the medium is
(a) 4
(b) 9
(c) 12
(d) 2
A parallel plate capacitor is made by stacking n equally spaced plates connected alternately. If the capacitance between any two plates is C, then the resultant capacitance is
(a) C
(b) nC
(c) (n-1)C
(d) (n+1)C
The potential energy of a charged parallel plate capacitor is \(U_0\). If a slab of dielectric constant K is inserted between the plates, then new potential energy will be
(a) \(U_0\)/K
(b) \(U_0\)K²
(c) \(U_0\)/K²
(d) \(U_0\)²
If the charge on each plate of a capacitor of 60μF is 3x\(10^{-8}\)C, then energy stored in the capacitor will be
(a) 2.5x\(10^{-15}\)J
(b) 1.5x\(10^{-14}\)J
(c) 3.5x\(10^{-13}\)J
(d) 7.5x\(10^{-12}\)J