Magnetic field of a short magnet at a distance lm on axial line is 1 oersted at a distance 2 m on the same line the intensity in oersted is
0.75
0.125
0.25
0.5
The ratio of magnetic moments of two short magnets which give null deflection in tan B position at 12 cm and 18 cm from the centre of a deflection magnetometer is
4:9
27:8
2:3
8:27
The distance between the poles of horse shoe magnet is 10 cm and its pole strength is 104 A. The magnetic field induction at point P mid-way between the poles is
4×10-19 tesla
2×10-9 tesla
zero
If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by respectively, then
C.
..In diamagnetic substances in each pair of electrons, the spin of both the electrons are in opposite directions. Hence, the electrons of each pair completely cancel the magnetic moment of each other. Thus, the net magnetic moment of each atom of such substances is zero i.e., .
The property of paramagnetism is found in those substances whose atoms, or molecules have an excess of electrons spinning in the same direction. Hence, atoms of paramagnetic substances have permanent magnetic moment ie, . The property of ferromagnetism is found in substances which acquire very strong magnetism when placed in an external magnetic field. Like the paramagnetic substances each atom of ferromagnetic substances also has a also has a permanent magnetic moment i.e, .
A frog can be levitated in magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
paramagnetic
diamagnetic
ferromagnetic
anti-ferromagnetic
A magnetic field exerts no force on
a magnet
an unmagnetised iron bar
a moving charge
stationary charge
An ideal solenoid having 5000 turns/m has an aluminium core and carries a current of 5A. If χAl = 2.3 × 10-5, then the magnetic field developed at centre will be
0.031 T
0.048 T
0.027 T
0.050 T
Assertion: In water, value of magnetic field decreases.
Reason: Water is a diamagnetic substance
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: Magnetic field lines are continuous and closed.
Reason: Magnetic monopole does not exist
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false
The temperature of transition from ferromagnetic property to paramagnetic property is called
Transition temperature
Critical temperature
Curie temperature
Triplet temperature