Electromagnetic...

A $$1.2m$$ wide track is parallel to the magnetic meridian. The verticle component of the earth's magnetic field is $$0.5$$ gauss. When a train runs on the rails at a speed of $$60Km/hr$$, then the induced potential difference between the ends of its axle will be __

Two cells of emf $$2V$$ and $$1.5 V$$ with internal resistance $$1 {\Omega}$$ each are connected in parallel similar poles joined together. The combination is connected to an external resistance of $$10{\Omega}$$. Find the current through the external resistance. 

Two coils A and B have mutual inductance $$2\times { 10 }^{ -2 }$$ henry. If the current in the primary is $$i=5\sin { \left( 10\pi t \right)  } $$ then the maximum value of e.m.f.induced in coil B is 

An electron moves on a staight line path $$XY$$ as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any,induced in the coil?

The magnetic induction at the centre $$O$$ in the figure shown is

A wire in the form of a square of side a caries a current i. Then the magnetic induction at the centre of the square wire is( Magnetic permeability of free space=$${ \mu  }_{ \circ  }$$)

A closely wound coil of 100 turns and area of cross section $$1{cm}^{2}$$ has a self-inductance 1 mH. The magnetic induction at the centre of the coil, when a current 2A flows in it, will be :

A wire carrying current $$I$$ is tied between points $$P$$ and $$Q$$ and is in the shape of a circular arch of radius $$R $$ due to a uniform magnetic field $$B$$ (perpendicular to the plane of the paper, shown by xxx) in the vicinity of the wire. If the wire subtends an angle $$2 \theta _o$$ at the centre of the circle (of which it form an arch) then the tension in the wire is :

A copper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per unit length of the frame the same, then the self inductance of the coil:

In the circuit shown, the power factor of the circuit is $$\dfrac { 3 }{ 5 }$$ , Power factor of only RC circuit is $$\dfrac { 4 }{ 5 }$$ , source voltage is $$100$$ volt and its angular frequency  $$\omega =100 rad/ sec$$. RMS current in circuit is A> If inductive reactance is greater then capacitive reactance then the value of self inductance L is