A hollow conducting sphere is placed in an electric field produced by a point charge placed at P as shown in the figure. Let\(V_A ~,V_B~,V_C\) be the potentials at points A, B and C respectively. Then:
1. \(V_A<V_B<V_C\)
2. \(V_A>V_B>V_C\)
3. \(V_C>V_B=V_A\)
4. \(V_A=V_B=V_C\)
The capacitance of a parallel plate capacitor is C. If a dielectric slab of thickness equal to one-fourth of the plate separation and dielectric constant K is inserted between the plates, then new capacitance become
1.
2.
3.
4.
A hollow charged metal spherical shell has radius R. If the potential difference between its surface and a point at a distance 3R from the center is V, then the value of electric field intensity at a point at distance 4R from the center is
1.
2.
3.
4.
Capacitors are connected in series across a source of emf 20KV. The potential difference across will be
(1) 5 KV
(2) 15 KV
(3) 10 KV
(4) 20 KV
In the circuit shown in figure, energy stored in 6 capacitor will be:
1. | \(48 \times10^{-6}~ \mathrm J\) | 2. | \(32 \times10^{-6}~ \mathrm J\) |
3. | \(96 \times10^{-6}~ \mathrm J\) | 4. | \(24 \times10^{-6}~ \mathrm J\) |
An air capacitor of capacity is connected to a constant voltage battery of 12 V. Now the space between the plates is filled with a liquid of dielectric constant 5. The charge that flows now from battery to the capacitor is
1. 120
2. 699
3. 480
4. 24
Two identical metal plates are given charges respectively. If they are now brought close to form a parallel plate capacitor with capacitance , the potential difference between them is :
1.
2.
3.
4.
A and B are two concentric metallic shells. If A is positively charged and B is earthed, then electric
1. Field at common centre is non-zero
2. Field outside B is nonzero
3. Potential outside B is positive
4. Potential at common centre is positive
Four equal charges Q are placed at the four corners of a square of each side is ‘a’. Work done in removing a charge – Q from its centre to infinity is
(1) 0
(2)
(3)
(4)
An electron of mass m and charge e is accelerated from rest through a potential difference V in vacuum. The final speed of the electron will be
(1)
(2)
(3)
(4)
Two equal charges q of opposite sign separated by a distance 2a constitute an electric dipole of dipole moment p. If P is a point at a distance r from the centre of the dipole and the line joining the centre of the dipole to this point makes an angle θ with the axis of the dipole, then the potential at P is given by (r >> 2a) (Where p = 2qa)
(1)
(2)
(3)
(4)
Inside a hollow charged spherical conductor, the potential -
(1) Is constant
(2) Varies directly as the distance from the centre
(3) Varies inversely as the distance from the centre
(4) Varies inversely as the square of the distance from the centre
Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No current will flow, if they have -
(1) The same charge on each
(2) The same potential
(3) The same energy
(4) The same field on their surfaces
Two spheres A and B of radius 4 cm and 6 cm are given charges of 80 μc and 40μc respectively. If they are connected by a fine wire, the amount of charge flowing from one to the other is -
(1) 20μc from A to B
(2) 16μc from A to B
(3) 32μc from B to A
(4) 32μc from A to B
In the figure the charge Q is at the centre of the circle. Work done by the conservative force is maximum when another charge is taken from point P to:
1. | K | 2. | L |
3. | M | 4. | N |
Two insulated charged conducting spheres of radii 20 cm and 15 cm respectively and having an equal charge of 10 C are connected by a copper wire and then they are separated. Then -
(1) Both the spheres will have the same charge of 10 C
(2) Surface charge density on the 20 cm sphere will be greater than that on the 15 cm sphere
(3) Surface charge density on the 15 cm sphere will be greater than that on the 20 cm sphere
(4) Surface charge density on the two spheres will be equal
Two equal charges q are placed at a distance of 2a and a third charge –2q is placed at the midpoint. The potential energy of the system is -
(1)
(2)
(3)
(4)
How much kinetic energy will be gained by an – particle in going from a point at 70 V to another point at 50 V ?
(1)
(2)
(3)
(4)
If identical charges (–q) are placed at each corner of a cube of side b, then electric potential energy of charge (+q) which is placed at centre of the cube will be -
(1)
(2)
(3)
(4)
A parallel plate condenser has a capacitance 50 μF in air and 110 μF when immersed in an oil. The dielectric constant ‘k’ of the oil is
(1) 0.45
(2) 0.55
(3) 1.10
(4) 2.20
Separation between the plates of a parallel plate capacitor is d and the area of each plate is A. When a slab of material of dielectric constant k and thickness t(t < d) is introduced between the plates, its capacitance becomes -
(1)
(2)
(3)
(4)
The capacity and the energy stored in a parallel plate condenser with air between its plates are respectively Co and Wo. If the air is replaced by the glass (dielectric constant = 5) between the plates, the capacity of the condenser and the energy stored in it will respectively be -
(1)
(2)
(3)
(4)
A 6 μF capacitor is charged from 10 volts to 20 volts. Increase in energy will be
(1) 18 × 10–4 J
(2) 9 × 10–4 J
(3) 4.5 × 10–4 J
(4) 9 × 10–6 J
A light bulb, a capacitor and a battery are connected together as shown below with the switch S initially open. When the switch S is closed, which one of the following is true?
1. The bulb will light up for an instant when
the capacitor starts charging.
2. The bulb will light up when
the capacitor is fully charged.
3. The bulb will not light up at all.
4. The bulb will light up and go off at regular intervals.
As in figure shown, if a capacitor C is charged by connecting it with resistance R, then energy given by the battery will be
(1)
(2) More than
(3) Less than
(4) Zero
Three capacitors are connected to D.C. source of 100 volts shown in the adjoining figure. If the charge accumulated on plates of C1, C2 and C3 are and qf respectively, then
(1)
(2)
(3)
(4)
Five capacitors of 10 μF capacity each are connected to a d.c. potential of 100 volts as shown in the adjoining figure. The equivalent capacitance between the points A and B will be equal to
(1) 40 μF
(2) 20 μF
(3) 30 μF
(4) 10 μF
A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of the resulting system
1. increases by a factor of 4
2.decreases by a factor of 2
3. remain the same
4. increases by a factor of 2
The diagrams below show regions of equipotentials.
A positive charge is moved from A to B in each diagram. Then:
1. | the maximum work is required to move q in figure(iii). |
2. | in all four cases, the work done is the same. |
3. | the minimum work is required to move q in the figure(i). |
4. | the maximum work is required to move q in figure(ii). |
A parallel-plate capacitor of area A, plate separation d, and capacitance C is filled with four dielectric materials having dielectric constants and as shown in the figure below. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant k is given by
(a)
(b)
(c)
(d)
A capacitor of 2 is charged as shown in the figure. When the switch S is turned to position 2, the percentage of its stored energy dissipated is:
1. | 20% | 2. | 75% |
3. | 80% | 4. | 0% |
A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
1. | The potential difference between the plates decreases K times |
2. | The energy stored in the capacitor decreases K times |
3. | The change in energy stored is \({1 \over 2} CV^{2}(\frac{1}{K}-1)\) |
4. | The charge on the capacitor is not conserved |
A parallel plate air capacitor has capacity C, distance of separation between plates is d and potential difference V is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is
(1)C2V2/2d
(2)CV2/2d
(3)CV2/d
(4)C2V2/2d2
Two thin dielectric slabs of dielectric constants K1&K2 () are inserted between plates of a parallel capacitor, as shown in the figure. The variation of electric field E between the plates with distance d as measured from plate P is correctly shown by
1.
2.
3.
4.
A conducting sphere of radius R is given a charge Q. The electric potential and field at the centre of the sphere respectively are
(a) zero and Q/4πoR2
(b)Q/4πoR and zero
(c)Q/4πoR and Q/4πoR2
(d)Both are zero
Four point charges are placed, one at each corner of the square.The relation between Q and q for which the potential at the centre of the square is zero, is
(1) Q=-q
(2)Q=-
(3)Q=q
(4)Q=
Two metallic spheres of radii 1 cm and 3 cm are given charges of -1 and , respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is:
1.
2.
3.
4.
A parallel plate condenser has a uniform electric field E(V/m) in the space between the plates. If the distance between the plates is d(m) and area of each plate is , the energy (joule) stored in the condenser is:
1.
2.
3.
4.
Four electric charges +q, + q, -q and -q are placed at the corners of a square of side 2L (see figure). The electric potential at point A, mid-way between the two charges +q and +q, is
(1)
(2)
(3) Zero
(4)
Three charges, each +q, are placed at the corners of an isosceles triangle ABC of sides BC and AC equal to 2a. D and E are the mid points of BC and CA. The work done in taking a charge Q from D to E is
(1)
(2)
(3)zero
(4)
(1) Centre of gravity (CG) of a body is the point at which the weight of the body acts.
(2) Centre of mass coincides with the centre of gravity if the earth is assumed to have infinitely
large radius.
(3) To evaluate the gravitational field intensity due to anybody at an external point, the entire mass
of the body can be considered to be concentrated at its CG.
(4) The radius of gyration of any body rotating about an axis is the length of the perpendicular
dropped from the CG of the body to the axis.
Which of the following pairs of statements is correct?
(a) (4) and (1) (b) (1) and (2)
(c) (2) and (3) (d) (3) and (4)
Three capacitors each of capacitance C and of breakdown voltage V are joined in series. The capacitance and breakdown voltage of the combination will be
(1)
(2)
(3)
(4)
A capacitor of capacitance 5 μF is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω. The amount of charge on the capacitor plate is?
(1) 0 μC
(2) 5 μC
(3) 10 μC
(4) 25 μC
Five identical plates each of area A are joined as shown in the figure. The distance between the plates is d. The plates are connected to a potential difference of V volts. The charge on plates 1 and 4 will be
(1)
(2)
(3)
(4)
A network of four capacitors of capacity equal to and C4 = 4 C are connected in a battery as shown in the figure. The ratio of the charges on C2 and C4 is
(1)
(2)
(3)
(4)