Magnetism and Matter
These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use:
If there is a uniform magnetic filed of 0.3 T in the positive z direction, in which orientations the loop would be in (i) stable equilibrium and (ii) unstable equilibrium?
Two short bar magnets of length 1 cm each have magnetic moments 1.20 A m2 and 1.00 A m2 respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South. They have a common magnetic equator and are separated by distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centres is close to (Horizontal component of earth’s magnetic induction is 3.6 × 10−5 Wb/m2)
The change in the magnetic dipole moment associated with the orbit, at the end of the time interval of the magnetic field change is
Reason Greater the value of susceptibility smaller the value of intensity of magnetisation I.
A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It :
A loop carrying current l lies in the x-y plane as shown in the figure. The unit vector is coming out of the plane of the paper. The magnetic moment of the current loop is
(i) For a permanent magnet the area of a hysteresis loop is allowed to large.
(ii) Coercivity of the material in permanent magnets should be small.
Which of the following statements is/are true?
Reason : The magnetisation does not depend on temperature.
In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields B1(solid line) and B2 (dashed line) . If B2 is larger than B1 which of the following graphs shows the correct variation of R with T in these fields?
A superconductor has Tc(0) = 100K. When a magnetic field of 7.5 Tesla is applied, its Tc decreases to 75 K. This material one can definitely say that when
Two bar magnets having same geometry with magnetic moments M and 2M, are placed in such a way that their similar poles are on the same side, then its time period of oscillation is T1. Now, if the polarity of one of the magnets is reversed, then time period of oscillation is T2, then