# Magnetism and Matter

## Physics

### NCERT

1   Answer the following questions regarding earth’s magnetism:$\\$ (a) A vector needs three quantities for its specification. Name the three independent quantities conventionally used to specify the earth’s magnetic field.$\\$ (b) The angle of dip at a location in southern India is about $18^o$ . Would you expect a greater or smaller dip angle in Britain?$\\$ (c) If you made a map of magnetic field lines at Melbourne in Australia, would the lines seem to go into the ground or come out of the ground?$\\$ (d) In which direction would a compass free to move in the vertical plane point to, if located right on the geomagnetic north or south pole?$\\$ (e) The earth’s field, it is claimed, roughly approximates the field due to a dipole of magnetic moment $8 * 1022JT^{-1}$ located at its centre. Check the order of magnitude of this number in some way.$\\$ (f) Geologists claim that besides the main magnetic N-S poles, there are several local poles on the earth’s surface oriented in different directions. How is such a thing possible at all?