1. A position detector comprising: first and second members mounted for relative movement along a measuring path; said first member comprising a magnetic field generator for generating a magnetic field; said second member comprising first and second conductors which are inductively coupled to said magnetic field generator, the first conductor extending in a geometrically varying manner having a first characteristic dimension along the measuring path and the second conductor extending in a geometrically varying manner having a second different characteristic dimension along the measuring path, as a result of which, in response to a magnetic field generated by said magnetic field generator, a first signal is generated in a first receive circuit which first signal varies in dependence upon the relative position and orientation of the first conductor and the magnetic field generator and a second different signal is generated in a second receive circuit which second signal varies in dependence upon the relative position and orientation of the second conductor and the magnetic field generator; and means for processing said first and second signals to determine the relative position and orientation of the two movable members using a relationship between the respective characteristic dimension of the geometrical variation of said two conductors.