Download hot magnetism

CLUSTER LEVEL WORK SHOP
SUBJECT
PHYSICS (MAGNETISM)
QUESTION BANK- HOT SKILL
1 Why are ferromagnetic materials used in memory devices?
ANS: The magnetization of ferromagnetic materials depends both on the applied
magnetic field and also on the history of magnetization
(i. e., how many cycles of magnetization it has gone through etc.) In other words, the
value of magnetization is a record or memory of its cycles of magnetization. Since
information bits can be made to correspond to these cycles. Therefore ferromagnetic
materials which show hysteresis loop are used in memory devices.
2
An electron moving through a magnetic field does not experience any force. Under what
condition is this possible?
Ans:
(i)
Charged particle is moving parallel and anti parallel to the magnetic field
(ii) Perpendicular electric field and magnetic field (both) exist in region and the
charged particle is moving perpendicular to both the fields. The field are such
that electric force and magnetic force cancel each other.
3 The following figure shows the variation of intensity of magnetization versus the applied
magnetic field intensity, Hj for two magnetic materials A and B:
(a) Identify the materials A and B.
(b) Why does the material B have a larger susceptibility than A for a given field at constant
temperature?
Ans:
(a) Material A is diamagnetic.
Material B is paramagnetic.
(b) Material B has a larger susceptibility than A because paramagnetic substances have a
tendency to pull in magnetic field lines when placed in a magnetic field.
4
An electron in an atom revolves around the nucleus in an orbit of radius 0.53 A0. Calculate the equivalent
magnetic moment if the frequency of revolution of the electron is 6.8 109 MHz
Ans:
M = IA= ev×𝜋𝑟 2 = 0.96×10-23Am2
5
The electron in the hydrogen atom is moving with a speed of 2.3  106 m/s in an orbit of radius
0.53 A0 . Calculate the magnetic moment of revolving electron.
Ans:
µ= evr/2 = 9.75×10-24Am2