NEET Physics Chapter Wise Mock Test – Electrostatics

NEET Physics Chapter Wise Mock Test – Electrostatics

Question 1:
When a glass rod rubbed with silk is brought near the gold leaf electroscope, the leaves diverge. What is the charge on the leaves?
(a) Negative
(b) Zero
(c) Positive
(d) Either positive or negative

Question 2:
A point positive charge is brought near an isolated conducting sphere, in figure shown. The electric field is best given by

(a) Fig. (i)
(b) Fig. (ii)
(c) Fig. (iii)
(d) Fig. (iv)

Question 3:
The excess (equal in number) of electrons that must be placed on each of two small spheres spaced 3 cm apart, with force of repulsion between the spheres to be10^-19 N, is
(a) 25
(b) 225
(c) 625
(d) 1250

Question 4:
In figure, two positive charges q₂ and q₃ fixed along the y-axis, exert a net electric force in the +x direction on a charge q₁ fixed along the x-axis. If a positive charge Q is added at (x,0), the force on q₁

(a) shall increase along the positive x-axis
(b) shall decrease along the positive x-axis
(c) shall point along the negative x-axis
(d) shall increase but the direction changes, because of the intersection of Q with q₂ and q₃

Question 5:
When air is replaced by a dielectric medium of constant K. The maximum force of attraction between two charges separated by a distance
(a) increases K^-1 times
(b) increases K times
(c) decreases K times
(d) remains constant

Question 6:
Two identical coins having similar charges are placed 4.5 m apart on a table. Force of repulsion between them is 40/9 N.The value of charge on each coin is
(a) 100 μC
(b) 200 μC
(c) 300 μC
(d) 400 μC

Question 7:
Three charges are placed at the vertices of an equilateral triangle of side a as shown in the figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is

(a) Q₂/(4πε₀a²)
(b) -Q₂/(4πε₀a²)
(c) zero
(d) Q₂(2πε₀a²)

Question 8:
The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance 5 x 10^-11 m,will be
(Charge of electron = 1.6x 10^-19 C, mass of electron = 9.1 x 10^-31kg, mass of proton = 1.6x 10^-27kg, G = 6.7x 10^-11N-m² kg^-2)
(a) 2.36 x 10³⁹
(b) 2.36 x 10⁴⁰
(c) 2.34x 10⁴
(d) 2.34x 10⁴²

Question 9:
The electric field due to a charge at a distance of 3 m from it is 500 NC^-1. The magnitude of the charge is [1/4πε₀ = 9x 10⁹Nm²C^-2]
(a) 2.5 μC
(b) 1.0 μC
(c) 2.0 μC
(d) 0.5 μC

Question 10:
An electron is sent in electric field of intensity 9.1 x 10⁶ NC^-1. The acceleration produced is (mass of electron = 9.1 x 10³¹ kg)
(a)1.6 ms^-2
(b) 1.6x 10¹⁸ ms^-2
(c) 3.2x 10¹⁸ ms^-2
(d) 0.8x 10¹⁸ ms^-2

Question 11:
A charged particle of mass 0.003 g is held stationary in space by placing it in a downward direction of electric field of 6×10⁴NC^-1. Then, the magnitude of the charge is
(a) 5 x 10^-4C
(b) 5 x 10^-10C
(c) 18xIO^-6C
(d) -5x 10^-9C

Question 12:
A parallel plate capacitor has an electric field of 105 Vm^-1 between the plates. If the charge on the capacitor plates is 1 nC, the force on each capacitor plate is
(a) 0.5 N
(b) 0.05 N
(c) 0.005 N
(d) None of these

Question 13:
Three point charges + q,-2q and +q are placed at points (x = 0, y =a, z = 0), (x =0, y = 0, z = 0) and (x = a, y = Q z = 0), respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are
(a) √2 aq along +y-direction
(b) √2 aq along the line joining points (x = 0,y = 0,z = 0) and (x = a,y = a,z = 0)
(c) qa along the line joining points (x = 0y = 0,z = 0) and (x = a,y = a,z = 0)
(d) √2 aq along + x-direction

Question 14:
Figure shows electric field lines in which an electric dipole p is placed as shown in figure. Which of the following statements is correct?

(a) The dipole will not experience any force
(b) The dipole will experience a force towards right
(c) The dipole will experience a force towards left
(d) The dipole will experience a force upwards

Question 15:
An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction the field, the force on it and its potential energy are respectively
(a) 2qE and minimum
(b) qE and pE
(c) zero and minimum
(d) qE and maximum

Question 16:
A hollow cylinder has a charge q coulomb within it. If Φ is the electric flux in unit of V-m associated with the curved surface 6, the flux linked with the plane surface A in unit of V-m will be

Question 17:
There exists an electric field of 1 N/C along y-direction. The flux passing through the square of 1m placed in xy plane inside the electric field is
(a) 1 Nm²/C
(b) 10 Nm²/C
(c) 2 Nm²/C
(d) zero

Question 18:
The electric flux for Gaussian surface A that enclose the charged particles in free space is
(Given q₁ = -14 nC, q₂ = 78.85 nC, q₃ = – 56 nC)

(a) 10³ Nm² C^-1
(b) 10³ Nm^-2C^-1
(c) 6.32 x 10³ Nm²C^-1
(d) zero

Question 19:
Consider the charge configuration and a spherical Gaussian surface as shown in figure. When calculating the flux of the electric field over the spherical surface, the electric field will be due to

(a) q₂
(b) only the positive charges
(c) all the charges
(d) +q₁ and – q₁

Question 20:
If the electric flux entering and leaving an enclosed surface respectively is Φ₁., and Φ₂, the electric charge inside the surface will be
(a) (Φ₁+Φ₂)ε₀
(b) (Φ₂-Φ₁)ε₀
(c) Zero
(d) Φ₂/ε₀

Question 21:
What is the total flux from the surface of cylinder of radius R and length L which is placed in a uniform electric field E parallel to cylinder axis?
(a) 2πR²E
(b) πR²E
(c) (πR + πR²)/E
(d) zero

Question 22:
A hemisphere surface of radius R is placed in uniform electric field of intensity E parallel to the axis of its circular plane. What will be the electric flux fi through the hemisphere surface?
(a) 2πRE
(b) 2πR²E
(c) πR²E
(d) (4/3) πR³E

Question 23:
What is the total electric flux leaving a spherical surface of radius 1 cm and surrounding at electric dipole?
(a) q/ε₀
(b) zero
(c) 2q/ε₀
(d) 8πR²q/ε₀

Question 24:
Two infinitely long parallel conducting plates having surface charge densities +σ and -σ respectively, are separated by a small distance. The medium between the plates is vacuum. If ε₀ is the dielectric permittivity of vacuum, then the electric field in the region between the plates is
(a) zero
(b) σ/2ε₀ Vm^-1
(c) σ/ε₀ Vm^-1
(d) 2σ/ε₀ Vm^-1

Question 25:
The electric charge on drop B is 1.6x 10^-19 C and its mass is 1.6x 10^-14 kg. If the drop is in equilibrium, then the potential difference between the plates will be (where, density d = 10 x 10^-3 kgm^-3)

(a) 5x 10⁵ V
(b) 10⁴ V
(c) 2×10⁴ V
(d) 10⁵ V

Question 26:
When n identical mercury droplets charged to the same potential V coalescence to form a single bigger drop. The potential of the new drop will be
(a) V/n
(b) nV
(c) nV²
(d) n^2/3 V

Question 27:
Which of the following is not the property of equipotential surfaces?
(a) They do not cross each other
(b) They are concentric spheres for uniform electric field
(c) Rate of change of potential with distance on them is zero
(d) They can be imaginary spheres

Question 28:
In a Van de Graaff generator, the voltage of a metallic spherical shell is 15 x10⁵ V and electric field around the electrode is 15 x 10⁷ Vm^-1,then the minimum radius of the metallic spherical shell
(a) 1 cm
(b) 2 cm
(c) 1m
(d) 2 m

Question 29:
Charges +q and -q are placed at points A and B respectively which are a distance 2L apart, C is the mid-point between A and B. The work done in moving a charge + Q along the semi-circle CRD is

Question 30:
Two charges q₁ and q₂ are placed 30 cm apart, as shown in the figure. A third charge q₃ is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the
system is q₃/4πε₀, where k is

(a) 8q₂
(b) 8q₁
(c) 6q₂
(d) 6q₁

Question 31:
The potential of a spherical conductor of radius 3 m is 6 V. The potential at its centre is
(a) zero
(b) 2V
(c) 6V
(d) 18V

Question 32:
Two identical metal plates are given positive charge Q₁ and Q₂ such that Q₁< Q₂ If they are now brought close to each other to form a parallel plate capacitor of capacitance C, the potential difference between them is

(a) (Q₁ + Q₂)/2C
(b) (Q₁ + Q₂)/C
(c) (Q₁ – Q₂)/C
(d) (Q₁ – Q₂)/2C

Question 33:
The electrostatic potential inside a charged spherical ball is given by Φ= ar² + b, where r is the distance from the centre and a, b are constants. Then, the charge density inside the bail is
(a) -3aε₀r
(b) – 6aε₀r
(c) +3aε₀r
(d) zero

Question 34:
If a battery is disconnected from the capacitor and then a dielectric substance between two plates of condenser is introduced the capacity, potential and potential energy respectively
(a) increases, decreases, decreases
(b) decreases, increases, increases
(c) increases, increases, increases
(d) decreases, decreases, decreases

Question 35:
A 0.2 μF capacitor is charged to 600 V. After removing it from battery. it is connected to another capacitor 1.0μF in parallel. The voltage on the capacitor will become
(a) 300 V
(b) 600 V
(c) 100 V
(d) 120 V

Question 36:
The equivalent capacitance of the following combination is

(a) 10μF
(b) 4μF
(c) 25μF
(d) 15μF

Question 37:
27 small drops each having charge q and radius r coalesce to form big drop. How many times charge and capacitance will become?
(a) 3, 27
(b) 27, 3
(c) 27, 27
(d) 3, 3

Question 38:
A thin aluminium sheet is placed between the plates of a parallel plate capacitor. Its capacitance will
(a) increase
(b) decrease
(c) remain same
(d) become infinite

Question 39:
Two condensers, one of capacity C and the other of capacity C/2, are connected to a V volt battery, as shown in figure. The work done in charging fully both the condensers is

(a) 2CV²
(b) 1/4 CV²
(c) 3/4 CV²
(d) 1/2 CV²

Question 40:
What will be the equivalent capacitance of the system as shown in the figure, where two spherical conductors A and B of radii a and b (b>a) are placed concentrically in air with a charge +Q on A and B being earthed?

(a) 4πε₀(ab/b-a)
(b) 4πε₀(a+b)
(c) 4πε₀b
(d) 4πε₀(b²/b-a)

Question 41:
A parallel plate capacitor of value 1.77 μF is to be designed using a dielectric material (dielectric constant =200), breakdown strength of 3x 10⁶ Vm^-1 . In order to make such a capacitor which can withstand a potential difference of 20 V across the plates, the separation between the plates d and area A of the plates respectively are

Question 42:
A capacitor having capacitance 1 μF with air, is filled with two dielectrics as shown in figure. How many times capacitance will increase?

(a) 12
(b) 6
(c) 8/3
(d) 3

Question 43:
The following figure shows seven capacitors, a switch S and a source of emf connected together. Initially S is open and all capacitors are uncharged.

What will be the potential difference in volts across the plates of the capacitor A, if S is closed afterwards and a steady state is attained?
(a) 12
(b) 15
(c) 17
(d) 19

Question 44:
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 statements is incorrect?
(a) The energy stored in the capacitor decreases K times.
(b) The charge in energy stored is 1/2 CV²(1/k-1)
(c) The charge on the capacitor is not conserved
(d) The potential difference between the plates decreases K times.

Question 45:
Two capacitors of capacitances 3 μF and 6 μF are charged to a potential of 12 V each. They are now connected to each other, with the positive plate of each joined to the negative plate of the other. The potential difference across each will be
(a) 4 V
(b) 6 V
(c) zero
(d) 3 V

Direction (Q. NOS. 46-52): In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) lf both Assertion and Reason are false

Question 46:

Question 47:
Assertion (A): The electric field due to a dipole on its axis line at a distance r is E. Then, electric field due to the same dipole on the equatorial line and at the same distance will be E/2
Reason (R): Electric field due to dipole varies inversely as the square of distance.

Question 48:
Assertion (A): A and B are two conducting spheres of same radius A being solid and B hollow. Both are charged to the same potential. Then, charge on A = charge on B.
Reason (R): Potentials on both are same.

Question 49:
Assertion (A): A molecule having intrinsic dipole moment is called polar molecule.
Reason (R): Centre of positive charge does not coincide with the negative charge in a polar molecule, because of asymmetric shape of molecule.

Question 50:
Assertion (A): A number of capacitors are connected in series with each other. If U₁,U₂,U₃… be the energy stored in them respectively, then total energy stored is U₁+U₂+U₃ + …
Reason (R): Potential energy is the scalar quantity.

Question 51:
Assertion (A): The coulomb force is the dominating force in the universe.
Reason (R): The coulomb force is weaker than the gravitational force.

Question 52:
Assertion (A): A small metal ball of mass m is suspended from a thread of length l between the plates of a large capacitor. If a charge +q is placed on the ball and the upper plate is positively charged, then time period of the ball increases.
Reason (R): Time period of the ball is given by

Question 53:
A point charge = q, is placed at a distance d from an isolated conducting plane. The field at a point P on the other side of the plane is
(a) directed perpendicular to the plane and away from the plane
(b) directed perpendicular to the plane but towards the plane
(c) directed radially away from the point charge
(d) directed radially towards the point charge

Question 54:

Question 55:
A number of condensers, each of the capacitance 1μF and each one of which gets punctured, if a potential difference just exceeding 500 V is applied, are provided. An arrangement suitable for giving capacitance of 2 μF across which 3000 V may be applied requires at least.
(a) 6 component capacitors
(b) 12 component capacitors
(c) 72 component capacitors
(d) 2 component capacitors

Question 56:
A capacitor of capacitance C has charge Q and stored energy is W. If the charge is increased to 2Q, the stored energy will be
(a) W/4
(b) W/2
(c) 2W
(d) 4W

Question 57:
A, B and C are three points in a uniform electric field. The electric potential is

(a) maximum at A
(b) maximum at 8
(c) maximum at C
(d) same at all the three points A, B and C

Question 58:
Which one of the following graphs represents the variation of electric field strength E with distance r from the centre of a uniformly charged non-conducting sphere?

Question 59:
Three charges +q₁,-q₁ and q₂ are placed as shown in figure, S is a Gaussian surface. Electric field at any point on S is

(a) due to q₂ only
(b) uniform at all points
(c) zero at all the points
(d) due to all the charges .

Question 60:
A parallel plate capacitor is located horizontally such that one of the plates is submerged in a liquid while the other is above the liquid surface. When plates are charged, the level of liquid

(a) rises
(b) falls
(c) remains unchanged
(d) may rise or fall depending on the amount of charge

Question 61:
A capacitor having capacity of 2.0 μF is charged to 220 V and then the plates of the capacitor are connected to a resistance wire. The heat produced in joule will be
(a) 2 x 10^-2
(b) 4 x 10^-2
(c) 4 x 10⁴
(d) 4 x 10¹⁰

Question 62:
Four point charges – Q, – q, 2q and 2Q 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
(a) Q = -q
(b) Q = -1/q
(c) Q = q
(d) Q=1/q

Question 63:
Assertion (A): A beam of charged particles is employed in the treatment of cancer.
Reason (R): Charged particles on passing through a material medium loss their energy by causing ionisation of the atoms along their path.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Question 64:
A small uncharged metallic sphere is positioned exactly at a point midway between two equal and opposite point charges. If the sphere is slightly displaced towards the positive charge and released, then
(a) it will oscillate about its original position
(b) it will move further towards the positive charge
(c) its electric potential energy will decrease and kinetic energy will increase
(d) its total energy remains constant but it non-zero

Question 65:
A capacitor of capacitance 5μF is connected as ‘ shown in the figure. The internal resistance of the cell is 0.5 12. The amount of charge on the capacitor plate is

(a) zero
(b) 5μC
(c) 10μC
(d) 25μC

Question 66:
Two capacitors of 10 μF and 20 μF are connected in series with a 30 V battery. The charge on the capacitors will be respectively
(a) 100 μC, 100 μC
(b) 200 μC,100 μC
(c) 200 μC, 200 μC
(d) 100 μC, 200 μC

Question 67:
A charge Q is divided into two parts of q and Q – q. If the coulomb repulsion between them when they are separated is to be maximum, the ratio of Q/q should be
(a) 2
(b) 1/2
(c) 4
(d) 1/4

Question 68:
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 A(m²). The energy (joule) stored in the condenser is

Question 69:
A charge Q is enclosed by a gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will
(a) be reduced to half
(b) remains the same
(c) be doubled
(d) increase four times

Question 70:
Four electric charges + q, + q,-q and – q are placed at the corners of a square of side 2L as see figure. The electric potential at point A, midway between the two charges + q and + q, is

Question 71:
A series combination of n₁ capacitors, each of value C₁ is charged by a source of potential difference 4V. When another parallel combination of n₂ capacitors, each of value C₂, is charged by a source of potential difference V, it has the same (total) energy stored in it, as the first combination has. The value of C₂, in terms of C₁, is then
(a) 2C₁/n₁n₂
(b) 16n₂C₁/n₁
(c) 2n₂C₁/n₁
(d) 16C₁/n₁n₂

Question 72:
A square surface of side L metre in the plane of the paper is placed in a uniform electric field E (V/m) acting along the same place at an angle 9 with the horizontal side of the square as shown in figure. The electric flux linked to the surface in unit of V-m, is

(a) EL²
(b) EL² cosθ
(c) EL² sinθ
(d) 0

Question 73:
Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be (e being the charge on an electron)

Question 74:
The equivalent capacitance between A and B for the combination of capacitors shown in figure, where all capacitances are in microfarad is

(a) 6.0μF
(b) 4.0μF
(c) 2.0μF
(d) 3.0μF

Question 75:

Question 76:

Question 77:
Charge Q is divided into two parts which are then kept some distance apart. The force between them will be maximum, if the two parts are having the charge
(a) Q/2 each
(b) Q/4 and 3Q/4
(c) Q/3 and 2Q/3
(d) e and (Q – e), where e = electronic charge

Question 78:
Identify the wrong statement in the following Coulomb’s law correctly described the electric force that
(a) binds the electrons of an atom to its nucleus
(b) binds the protons and neutrons in the nucleus of an atom
(c) binds atoms together to form molecules
(d) binds atoms and molecules to form solids

Answers:

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