A measurement of the weak form factor of the proton allows a separation of the strangeness contribution to the electromagnetic form factors. The weak form factor is accessed experimentally by the measurement of a parity violating (PV) asymmetry in the scattering of polarized electrons on unpolarized protons. We performed such measurements with the setup of the A4-experiment at the MAMI accelerator facility in Mainz. The role of strangeness in low energy nonperturbative QCD is discussed. The

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... periment is presented as well as the results on the strangeness form factors which have been measured at two Q 2 -values. The plans for backward angle measurements at the MAMI facility are presented. PACS. 12.15.-y Electroweak interactions -11.30.Er Charge conjugation, parity, time reversal, and other discrete symmetries -13.40.Gp Electromagnetic form factors -25.30.Bf Elastic electron scattering