The earth's core is known to contain Iron. Yet geologists do not regard this as a source of the earth's magnetism. Why?

Acid rain is known to contain some acids. Name these acids and mention their source.

A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip down at 60^@ with the horizontal. The horizontal component of the earth's magnetic field at the place is known to be 0.4G. Determine the magnitude of the earth's magnetic field at the place.

A wire is kept horizontally at a place in the northern hemisphere of the earth . In what direction will force act on the wire due to the vertical component of the earth's magnetic field , if electric current flows through the wire from south to north ?

Define the components of earths magnetic field.

A short bar magnet is placed with its north towards north of the earth. A neutral point is obtained on its equational line at a distance of 0.15 m from the centre of the magnet. If the horizontal component of the earth's magnetic field is 0.34 G, find the magnetic dipole moment of the magnet.

Be and Mg do not give colour to flame whereas other alkaline earth metals do so. Why?

Which of the following forests is known as the 'lungs of the planet earth'?