The magnetic moment of a diamagnetic atom is 

• much greater than one

• one

• equal to zero

• equal to zero

Two identical bar magnets are fixed with their centres at a distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the centre O as shown in the figure.


The force on the charge Q is

• zero

• directed along OP

• directed along PO

• directed along PO

A rectangular, a square a circular and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with a constant velocity, The magnetic field is directed along the negative z- axis direction. The induced emf, during the passage of these loops, out the field region, will not remain constant for

• the rectangular, circular and elliptical loops

• the circular and the elliptical loops

• only the elliptical loops

• only the elliptical loops

Curie temperature is the temperature above which

• ferromagnetic material becomes paramagnetic material

• paramagnetic material becomes diamagnetic material

• paramagnetic material becomes ferromagnetic material

• paramagnetic material becomes ferromagnetic material

Above Curie temperature

• a ferromagnetic substance becomes paramagnetic

• a paramagnetic substance becomes diamagnetic

• a diamagnetic substance becomes paramagnetic

• a diamagnetic substance becomes paramagnetic

A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is

• 9.1 μJ

• 4.55 μJ

• 2.3 μJ

• 2.3 μJ

17.

Figure shows a circuit contains three identical resistors with resistance R = 9.0 Ω each, two identical inductors with inductance L = 2.0 mH each, and an ideal battery with emf  ε= 18 V. The current'i' through the battery just after the switch closed is

• 2 mA

• 0 mA

• 2 A

• 2 A

A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from

• The current source

• The magnetic field

• The induced electric field due to the changing magnetic field

• The lattice structure of the material of the rod

In the given figure, what is the magnetic field induction at point O.

• $\frac{{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{4\mathrm{\pi r}}$

• $\frac{{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{4\mathrm{r}} + \frac{{\mathrm{\mu }}_{\mathrm{o}} \mathrm{I}}{2\mathrm{\pi r}}$

• $\frac{{\mathrm{\mu }}_0 \mathrm{I}}{4\mathrm{r}} + \frac{{\mathrm{\mu }}_0 \mathrm{I}}{4\mathrm{\pi r}}$

• $\frac{{\mathrm{\mu }}_0 \mathrm{I} }{4\mathrm{r}} - \frac{{\mathrm{\mu }}_0 \mathrm{I}}{4\mathrm{\pi } \mathrm{r}}$

A uniform electric field and a uniform magnetic field acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then

• It will turn towards the left of the direction of motion.

• It will turn towards the right of the direction of motion

• Its velocity will increase

• Its velocity will decrease