# Unseen Passage

For Class 4 to Class 12

# Electric Charges and Fields MCQ Class 12 Physics

Please refer to Chapter 1 Electric Charges and Fields MCQ Class 12 Physics with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Physics. Students should refer to MCQ Questions for Class 12 Physics with Answers to score more marks in Grade 12 Physics exams. Students should read the chapter Electric Charges and Fields and then attempt the following objective questions.

## MCQ Questions Class 12 Physics Chapter 1 Electric Charges and Fields

The Electric Charges and Fields MCQ Class 12 Physics provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. Two similar spheres having +Q and -Q charges are kept at a certain distance. F force acts between the two. If at the middle of two spheres, another similar sphere having +Q charge is kept, then it experiences a force in magnitude and direction as
(a) zero having no direction.
(b) 8F towards +Q charge.
(c) 8F towards -Q charge.
(d) 4F towards +Q charge.

C

Question. Pick the correct statement from the following
(a) If the point has a charge then the electric field is discontinuous at the point.
(b) Continous electric field at a point
(c) Continous electric field at a point if a charge is present at the point.
(d) At the point, the electric field is discontinuous if a negative charge is present at the point.

A

Question. When a glass rod is rubbed with silk, it
(a) gains electrons from silk.
(b) gives electrons to silk.
(c) gains protons from silk.
(d) gives protons to silk.

B

Question. The electric field inside a spherical shell of uniform surface charge density is
(a) zero.
(b) constant, less than zero.
(c) directly proportional to the distance from the centre.
(d) none of the these

A

Question. The electric field intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance rir r(r > R) from its axis is
(a) directly proportional to r².
(b) directly proportional to r3.
(c) inversely proportional to r.
(d) inversely proportional to r².

C

Question. Which of the following statements is not true about Gauss’s law?
(a) Gauss’s law is true for any closed surface.
(b) The term q on the right side side of Gauss’s law includes the sum of all charges enclosed by the surface.
(c) Gauss’s law is not much useful in calculating electrostatic field when the system has some symmetry.
(d) Gauss’s law is based on the inverse square dependence on distance contained in the coulomb’s law

C

Question. The magnitude of electric field intensity E is such that, an electron placed in it would experience an electrical force equal to its weight is given by
(a) mge
(b) mg/e
(c) e/mg
(d) e²g/m²

B

Question. Gauss’s law will be invalid if
(a) there is magnetic monopoles.
(b) the inverse square law is not exactly true.
(c) the velocity of light is not a universal constant.
(d) none of these.

B

Question. At a distance r, two equal charges are kept and they exert a force F on each other. What is the force acting on each charge, if the distance between them is doubled and charges are halved?
(a) F/4
(b) 4 F
(c) F/16
(d) F/8

C

Question. Electric field lines provide information about
(a) field strength
(b) direction
(c) nature of charge
(d) all of these

D

Question. Consider a region inside which, there are various types of charges but the total charge is zero. At points outside the region
(a) the electric field is necessarily zero.
(b) the electric field is due to the dipole moment of the charge distribution only.
(c) the dominant electric field is inversely pro-portional to r3, for large r (distance from ori-gin).
(d) the work done to move a charged particle along a closed path, away from the region will not be zero.

C

Question. If an electric dipole is kept in a uniform electric field then resultant electric force on it is :
(a) always zero
(b) never zero
(c) depend upon capacity of dipole
(d) None

A

Question. Electric field at a point varies as r° for
(a) an electric dipole
(b) a point charge
(c) a plane infinite sheet of charge
(d) a line charge of infinite length

C

Question. If sphere of bad conductor is given charge then it is distributed on:
(a) surface
(b) inside the surface
(c) only inside the surface
(d) None

D

Question. Each of the two point charges are doubled and their distance is halved. Force of interaction becomes p times, w here p is :
(a) 1
(b) 4
(c) 1/16
(d) 16

D

Question. A parrot comes and sits on a bare high power line. It will:
(a) experience a mild shock ‘
(b) experience a strong shock.
(c) get killed instantaneously
(d) not be affected practically

D

Question. Charge is
(a) transferable
(b) associated with mass
(c) conserved
(d) All of these

D

Question. Gauss’s law will be invalid if
(a) there is magnetic monopoles.
(b) the inverse square law is not exactly true.
(c) the velocity of light is not a universal constant.
(d) none of these.

B

Question. If a body is negatively charged, then it has
(a) excess of electrons
(b) excess of protons
(c) deficiency of electrons
(d) deficiency of neutrons

A

Question. If an object possesses an electric charge, it is said to be electrified or … A … When it has no charge, it is said to be … B … Here, A and B refer to
(a) charged, neutral
(b) neutral, charged
(c) discharged, charged
(d) active, reactive

A

Question. Quantisation of charge was experimentally demonstrated by
(a) Einstein’s photoelectric effect
(b) Frank-Hertz experiment
(c) Davisson and Germer experiment
(d) Millikan’s oil drop experiment

D

Question. Coulomb’s law is true for
(a) atomic distances (= 10–11 m)
(b) nuclear distances (= 10–15 m)
(c) charged as well as uncharged particles
(d) all the distances

D

Question. In general, metallic ropes are suspended on the carriers taking inflammable materials. The reason is
(a) to control the speed of the carrier.
(b) to keep the centre of gravity of the carrier nearer to the earth.
(c) to keep the body of the carrier in contact with the earth.
(d) none of these.

C

Question. If the dipole of moment 2.57 × 10–17 cm is placed into an electric field of magnitude 3.0 × 104 N/C such that the fields lines are aligned at 30° with the line joining P to the dipole, what torque acts on the dipole?
(a) 7.7 × 10–13 Nm
(b) 3.855 × 10–13 Nm
(c) 3.855 × 10–15 Nm
(d) 7.7 × 10–15 Nm

B

Question. 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) 2:1
(b) 1/2
(c) 4:1
(d) 1/4

A

Question. The unit of electric dipole moment is
(a) newton
(b) coulomb
(d) debye

D

Question. The electric field inside a spherical shell of uniform surface charge density is
(a) zero.
(b) constant, less than zero.
(c) directly proportional to the distance from the center.
(d) none of the these

A

Question. Which of the following statement is correct? The electric field at a point is
(a) always continuous.
(b) continuous if there is a charge at that point.
(c) discontinuous only if there is a negative charge at that point.
(d) discontinuous if there is a charge at that point.

D

Question. The force per unit charge is known as
(a) electric flux
(b) electric field
(c) electric potential
(d) electric current

B

Question. Which surface is considered for Gauss law?
(a) Spherical surface
(b) Closed Surface
(c) Gaussian Surface
(d) Plane Surface

C

Question. 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 Times
(b) Remains Unchanged
(c) Decreases K Times
(d) Increases K-1 Times

C

Question. Electric field at a point varies as r° for
(a) an electric dipole
(b) a point charge
(c) a plane infinite sheet of charge
(d) a line charge of infinite length

C

Question. Two metal plates form a parallel plate capacitor. The distance between the plates is d. A metal sheet of thickness frac{d}{2} and of the same area is introduced between the plates.
What is the ratio of the capacitance in the two cases?
(a) 2 : 1
(b) 3 : 1
(c) 2 : 1
(d) 5 : 1

C

Question. 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) 2:1
(b) 1/2
(c) 4:1
(d) 1/4

A

Question. If an electric dipole is kept in a uniform electric field then resultant electric force on it is :
(a) always zero
(b) never zero
(c) depend upon capacity of dipole
(d) None

A

Question. Various properties of charge include?
(b) Conservation of Electric Charge
(c) Quantization of Electric Charge
(d) All of the above

D

Question. The surface considered for Gauss’s law is called
(a) Closed surface
(b) Spherical surface
(c) Gaussian surface
(d) Plane surface

C

Question. Which of the following is the best insulator?
(a) Carbon
(b) Paper
(c) Graphite
(d) Ebonite

D

Question. Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum
(a) 12.5 Q
(b) 13.5 Q
(c) 14.5 Q
(d) 16.5 Q

A

Question. Equipotentials at a great distance from a collection of charges whose total sum is not zero are approximately
(a) Sphers
(b) Planes
(c) Paraboloids
(d) Ellipsoids

A

Question. A square surface of side L meter in the plane of the paper is placed in a uniform electric field E (volt/m) acting along the same plane at an angle Θ with the horizontal side of the square as shown in Figure. The electric flux linked to the surface, in units of volt. m, is

(a) EL2
(b) EL2 cos Θ
(c) EL2 sin Θ
(d) zero

Ans

D

Question. A point positive charge is brought near an isolated conducting sphere (figure). The electric field is best given by

Ans

A

Question. A hemisphere is uniformely charged positively. The electric field at a point on a diameter away from the centre is directed
(a) perpendicular to the diameter
(b) parallel to the diameter
(c) at an angle tilted towards the diameter
(d) at an angle tilted away from the diameter

Ans

A

Question. Figure shows electric field lines in which an electric dipole P is placed as shown. 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

Ans

C

Question. The electric flux through the surface

(a) in Fig. (iv) is the largest
(b) in Fig. (iii) is the least
(c) in Fig. (ii) is same as Fig. (iii) but is smaller than Fig. (iv)
(d) is the same for all the figures

Ans

D

Question. An electric dipole of dipole moment p is aligned parallel to a uniform electric field E. The energy required to rotate the dipole by 90° is
(a) pE2
(b) p2E
(c) pE
(d) infinity

Ans

C

Question. The electric field in a certain region is acting radially outward and is given by E = Aa. A charge contained in a sphere of radius ‘a’ centred at the origin of the field, will be given by
(a) A e0 a2
(b) 4 π∈0 Aa3
(c) ∈0 Aa3
(d) 4 π∈0 Aa2

Ans

B

Question. Two identical charged spheres suspended from a common point by two massless strings of lengths l, are initially at a distance d (d << l ) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then v varies as a function of the distance x between the spheres, as :

Ans

C

Question. Suppose the charge of a proton and an electron differ slightly. One of them is – e, the other is (e + ∆e). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then De is of the order of [Given mass of hydrogen mh = 1.67 × 10–27 kg]
(a) 10–23C
(b) 10–37 C
(c) 10–47 C
(d) 10–20 C

Ans

B

Question. Three charges, each +q, are placed at the corners of an isosceles triangle ABC of sides BC and AC, 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

Ans

C

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