If a charged particle moves through a magnetic field perpendicular to it
Answer: energy is constant but momentum changes.
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,
Answer: Some charges inside the wire move to the surface as a result of B.
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,
Answer: the magnetic forces on both the particles cause equal accelerations.
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
In a cyclotron, a charged particle [NCERT Exemplar]
Answer: undergoes acceleration all the time.
An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true? [NCERT Exemplar]
Answer: The electron will continue to move with uniform velocity along the axis of the solenoid
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]
Answer: The magnitude of magnetic moment now diminishes.
If the magnetising field on a ferromagnetic material is increased, its permeability.
Lines of force, due to earth’s horizontal magnetic field, are
Answer: parallel and straight
Angle of dip is 90° at
Curie law xT = constant, relating magnetic susceptibility (x) and absolute temperature (T) of magnetic substance is obeyed by
Answer: paramagnetic substances.
The material suitable for making electromagnets should have
Answer: high retentivity and low coercivity.
Curie temperature is the temperature above which
Answer: a ferromagnetic material becomes paramagnetic.
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
Answer: attract N1 strongly, N2 weakly and repel N3 weakly.
A magnetic needle is kept in a non-uniform magnetic field. It experiences
Answer: a force and a torque.
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: can be zero at specific points.
Essential difference between electrostatic shielding by a conducting shell and magne-tostatic shielding is due to
Answer: lines of B cannot end. on any material and perfect shielding is not possible.
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 .
Answer: The H field in the solenoid is (nearly) unchanged but the B field decreases drastically.
The primary origin(s) of magnetism lies in
Answer: polar nature of molecules.
S is the surface of a lump of magnetic material.
Answer: Lines of H cannot all be continuous across S.