cbse class 11 physics multiple choice questions with answers
Questions
Free download in PDF CBSE Class 11 Physics Multiple Choice Questions(MCQs) with Answers. Here Gkseries provide Physics Solve Questions and Answers for CBSE Class 11 Students.
61
If a charged particle moves through a magnetic field perpendicular to it
62
Consider a wire carrying a steady current, I placed in a uniform magnetic field B perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do not work. This implies that,
A
motion of charges inside the conductor is unaffected by B, since they do not absorb energy.
B
Some charges inside the wire move to the surface as a result of B.
C
if the wire moves under the influence of B, no work is done by the force.
D
If the wire moves under the influence of B, no work is done by the electric force on the ions, assumed fixed within the wire.
63
A cubical region of space is filled with some uniform electric and magnetic fields. An electron enters the cube across one of its faces with velocity v and a positron enters via opposite face with velocity -v. At this instant,
A
the electric forces on both the particles cause identical accelerations.
B
the magnetic forces on both the particles cause equal accelerations.
C
Only electron gains or looses energy.
D
the motion of the centre of mass (CM) is determined by E alone.
Answer: the magnetic forces on both the particles cause equal accelerations.
64
A circular coil of radius 4 cm and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5 weber/m². The magnetic dipole moment of the coil is
Answer: The electron will continue to move with uniform velocity along the axis of the solenoid
67
A current carrying circular loop of radius R is placed in the x-y plane with centre at the origin. Half of the loop with x > 0 is now bent so that it now lies in the y – z plane. [NCERT Exemplar]
A
The magnitude of magnetic moment now diminishes.
B
The magnetic moment does not change.
C
The magnitude of B at (0.0.z), z» R increases.
D
The magnitude of B at (0, 0, z), z » R is unchanged.
Answer: a ferromagnetic material becomes paramagnetic.
74
Three needles N1 N2 and N3 are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet, when brought close to them, will
A
attract N1 strongly, but repel N2 and N3 weakly.
B
attract all three of them.
C
attract N1 and N2 strongly but repel N3.
D
attract N1 strongly, N2 weakly and repel N3 weakly.
76
Let the magnetic field on earth be modelled by that of a point magnetic dipole at the centre of earth. The angle of dip at a point on the geographical equator
Answer: lines of B cannot end. on any material and perfect shielding is not possible.
78
A long solenoid has 1000 turns per metre and carries a current of 1 A. It has a soft iron core of μr = 1000. The core is heated beyond the Curie temperature, Tc .
A
The H field in the solenoid is (nearly) unchanged but the B field decreases drastically.
B
The H and B fields in the solenoid are nearly unchanged.
C
The magnetisation in the core reverses direction.
D
The magnetisation in the core does not diminishes.
