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Free download in PDF CBSE Class 12 Physics Multiple Choice Questions(MCQs) & Answers. Here Gkseries provide Physics Solve Questions and Answers for CBSE Class 12 Students.
(1)
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.
(2)
The surface considered for Gauss’s law is called
[A]
Closed surface
[B]
Spherical surface
[C]
Gaussian surface
[D]
Plane surface
(3)
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.
Answer: the dominant electric field is inversely pro-portional to r3, for large r (distance from ori-gin).
(4)
The unit of electric dipole moment is
[A]
debye
[B]
farad
[C]
newton
[D]
coulomb
(5)
Electric field lines provide information about
[A]
nature of charge
[B]
direction
[C]
field strength
[D]
all of these
(6)
The force per unit charge is known as
[A]
electric flux
[B]
electric field
[C]
electric potential
[D]
electric current
(7)
SI unit of permittivity of free space is
[A]
C2N-1 m-2
[B]
C2N-1 m-2
[C]
Farad
[D]
None of these
(8)
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.
(9)
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
(10)
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.
(11)
Electric field at a point varies as r° for
[A]
a plane infinite sheet of charge
[B]
a line charge of infinite length
[C]
an electric dipole
[D]
a point charge
Answer: a plane infinite sheet of charge
(12)
The electric field inside a spherical shell of uniform surface charge density is
[A]
directly proportional to the distance from the centre.
[B]
zero.
[C]
constant, less than zero.
[D]
none of the these
(13)
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]
1/4
[C]
1/2
[D]
4:1
(14)
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.
(15)
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.
Answer: to keep the body of the carrier in contact with the earth.
(16)
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.
Answer: gives electrons to silk.
(17)
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.
Answer: discontinuous if there is a charge at that point.
(18)
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 [NCERT Exemplar]
[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.
(19)
The SI unit of electric flux is
[A]
N C-1 m-2
[B]
N C m-2
[C]
N C-1 m2
[D]
N C-2 m2
(20)
A positively charged particle is released from rest in an uniform electric field. The electric potential energy of the charge [NCERT Exemplar]
[A]
decreases because the charge moves along the electric field.
[B]
decreases because the charge moves opposite to the electric field.
[C]
remains a constant because the electric field is uniform.
[D]
increases because the charge moves along the electric field.
Answer: decreases because the charge moves along the electric field.
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