NCERT Solutions for class 12 Physics | Chapter 1 - Electric Charges and Fields

Sports GK Questions and Answers 2024 (Latest Updated)

Awards & Honours GK Questions 2024 (Latest Updated)

Questions
1 1 V equals to:
A 1 J
B 1 JC-1
C 1 CJ-1
D 1 JC

Answer:1 JC-1
2 When a dipole of moment Electric Charges and Fields
A
B
C
D

Answer:
Advertisement
3 A semicircular arc of radius r is charged uniformly and the charge per unit length is λ. The electric field at the centre is:
A
B
C Electric Charges and Fields
D

Answer:
4 Four charges are arranged at the comers of a square ABCD, as shown. The force on the charge kept at the centre O is

Electric Charges and Fields

A zero
B along the diagonal AC
C along the diagonal BD
D perpendicular to side AB

Answer:along the diagonal BD
5 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

Answer:Gauss’s law is not much useful in calculating electrostatic field when the system has some symmetry.
6 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.

Answer:the inverse square law is not exactly true.
7 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.

Answer:directed perpendicular to the plane and away from the plane.
8 Which of the following statement is correct? The electric field at a point is [NCERT Exemplar]
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.

Answer:discontinuous if there is a charge at that point.
9 In Fig. (i) 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) in figure (ii), the force on q1 is

Electric Charges and Fields

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 qy

Answer:shall increase along the positive x-axis.
10 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

Answer:mg/e
11 A point charge q is placed at a distance a/2 directly above the centre of a square of side a. The electric flux through the square is
A
B
C
D

Answer:
12 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.

Answer:inversely proportional to r.
13 Total electric flux coming out of a unit positive charge kept in air is
A ε0
B Electric Charges and Fields
C (4πε0)-1
D 4πε0

Answer:Electric Charges and Fields
14 An electric charge q is placed at the centre of a cube of side a. The electric flux on one of its faces will be
A
B Electric Charges and Fields
C
D

Answer:
15 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

Answer:a plane infinite sheet of charge
16 A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by
A
B
C
D Zero

Answer:Zero
17 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

Answer:zero.
18 Two charges of equal magnitudes kept at a distance r exert a force F on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is
A F/8
B F/4
C 4F
D F/16

Answer: F/16
19 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

Answer:2:1
20 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.

Answer:8F towards -Q charge.

Chapters

apsc cce prelims 2025