The magnetic field at a perpendicular distance of 2 cm from an infinite straight current carrying conductor is 2x10^-6 T. The current in the wire is

A positive charge is moving towards an observer. The direction of magnetic induction lines is 

If a copper wire carries a direct current, the magnetic field associated with the current will be

A thin ring of radius R metre has charge q coulomb uniformly spread on it. The ring rotates about its axis with a constant frequency of f revolutions/s. The value of magnetic field induction in Wb/m² at the centre of the ring is 

Ampere's circuital law can be derived from

Name the physical quantity whose unit is tesla. Hence define a tesla.

Where is the magnetic field of a current element (i) minimum and (ii) maximum?

Where is the magnetic field due to current through circular loop is
(i) uniform and
(ii) non-uniform ?

How will the magnetic field strength at the centre of the circular coil carrying current change, if the current through the coil is doubled and the radius of the coil is halved?

A current is set up in a long copper pipe. Is there a magnetic field
(a) inside
(b) outside the pipe ?

An \(\alpha \) -particle and a proton are moving in the plane of the paper in a region where there is a uniform magnetic field \(\overset { \rightarrow }{ B } \)  directed normal to the plane of paper. If the two particles have equal linear momenta, what will be the ratio of their trajectories in the field?

A wire of length l metre carries a current I ampere along the Y-axis. A magnetic field, \(\overset { \rightarrow }{ B } ={ B }_{ o }\left( \hat { i } +\hat { j } +\hat { k } \right) \)tesla exists in space. Find the magnitude of the force on the wire.

(a) What is the importance of a radical magnetic field and how is it produced?
(b) Why is it that while using a moving coil galvanometer as a voltmeter, a high resistance in series is required whereas in an ammeter a shunt is used?
(c) With the help of a diagram, explain the principle and working of a moving coil galvanometer.

An electron travels in a circular path of radius 20 cm in a magnetic field of 2 \(\times\) 10^-3 T.  Calculate the speed of the electron.  What is the potential difference through which the electron must be accelerated to acquire this speed?

A long straight horizontal cable carries a current of 2.5A in the direction 10^o south of west to 10^o north of east. The magnetic meridian of the place happens to be 10^o west of the geographic meridian, The earth's magnetic field at the location is 0.33G, and the angle of dip is zero. Locate the line of neutral points(Ignore the thickness of the cable).

A closely wound solenoid of 2000 turns and area of cross-section 1.6 x 10^-4m² carrying a current of 4.0A is suspended through its centre allowing it to turn in a horizontal plane.
(a) What is the magnetic moment associated with the solenoid?
(b) What is the force and torque on the solenoid if a uniform horizontal magnetic field of 7.5 x 10^-2T is set up at an angle of 30^o with the axis of the solenoid?

Assume the dipole model for earth's magnetic field B which by \({ B }_{ v }=\)vertical component of magnetic field = \(\frac { { \mu }_{ 0 } }{ 4\pi } \frac { 2M\cos { \theta } }{ { r }^{ 3 } } { B }_{ H }=\) Horizontal component of magnetic field = \(\frac { { \mu }_{ 0 } }{ 4\pi } \frac { 2M\sin { \theta M } }{ { r }^{ 3 } } ,\theta ={ 90 }^{ \circ }=\) lattitude as measured from magnetic equator. Find loci of points for which
(i) \(\left| B \right| \) is minimum
(ii) dip angle is zero and
(iii) dip angle is\(\pm { 45 }^{ \circ }\).