A wheel with 25 metallic spokes each 0.4m long is rotated with a speed of 150 `rev//min` in a plane normal to the horizontal components of earth's magnetic field `H_B` at a place. If `H_E=0.4G` at the place, what is the induced emf between the axle and the rim of the wheel?

In the magnetic meridian of a certain place, the horizontal component of the eath's magnetic field is 0.26G and the dip angle is 60^@ . What is the magnetic field of the earth at this location?

A metal rod of length L meter rotates about one end in a vertical plane at right angles to the magnetic-meridian. Frequency of revolution is f Hz.If the horizontal component of Earth's magnetic field is H Tesla then find the expression of inducted emf between the ends of the rod.

Find the value of the vertical component and resultant intensity of the earth's magnetic field at a place where H is 0.2 G and angle of dip is 60°.

Two rails of a railway track insulated from each other and the ground are connected to a milli voltmeter. What is the reading of millivoltmeter when the train travels at speed of 180 km/h along the track, given that the horizontal component of earth's magnetic field is 0.2*10^(-4) wb/m and the rails are separated by 1 meter.