Earth's Magnetic Field

Assertion : Earth's magnetic field does not affect the working of a moving coil galvanometer. Reason: The earth's magnetic field is quite weak as compared to magnetic field produced in the moving coil galvanometer.

The earth's magnetic field is approximately like that of a giant magnetic dipole, whose axis is inclined roughly 20^@ west of the axis of rotation of earth which is the geographic N-S direction. The strength of earth's magnetic field is of the order of 10^-4 tesla . Three magnetic elements of earth are: Magnetic declination (theta) , magnetic inclination or magnetic dip (delta) and horizontal component (H) of earth's magnetic field. Magnetic declination is the small angle between magnetic axis and geographic axis at a place. Magnetic dip at a place is the angle, which the direction of total strength of earth's magnetic field (R) makes with a horizontal line in magnetic meridian. If H is horizontal component and V is vertical component of earth's magnetic field, then H=Rcos delta , V=Rsin delta and R=sqrt(H^2+V^2) . At a place on the surface of earth. H is of the order of 3*3xx10^-5tesla . Magnetic declination is

The earth's magnetic field is approximately like that of a giant magnetic dipole, whose axis is inclined roughly 20^@ west of the axis of rotation of earth which is the geographic N-S direction. The strength of earth's magnetic field is of the order of 10^-4 tesla . Three magnetic elements of earth are: Magnetic declination (theta) , magnetic inclination or magnetic dip (delta) and horizontal component (H) of earth's magnetic field. Magnetic declination is the small angle between magnetic axis and geographic axis at a place. Magnetic dip at a place is the angle, which the direction of total strength of earth's magnetic field (R) makes with a horizontal line in magnetic meridian. If H is horizontal component and V is vertical component of earth's magnetic field, then H=Rcos delta , V=Rsin delta and R=sqrt(H^2+V^2) . At a place on the surface of earth. H is of the order of 3*3xx10^-5tesla . At magnetic poles, a compass needle points out

At a place on earth, horizontal component of earth's magnetic field is B_(1) and vertical component of earth's magnetic field si B_(2) . If a magnetic needle is kept vertica, in a plane making angle alpha with the horizontal component of magnetic field, then square of time period of oscillation of needle when slightly distributed is proportional to