  We study electromagnetic form factors of protons in proton-nucleus scattering
via analysing of experimental cross-sections of accompanying bremsstrahlung
photons. A new bremsstrahlung model for proton-nucleus scattering is developed,
where a main focus is given on incoherent bremsstrahlung that has not been
considered previously. In analysis we choose experimental bremsstrahlung data
of $p$ + $^{197}$Au scattering at proton beam energy of 190 MeV obtained by
TAPS collaboration. We find the following. (1) Inclusion of incoherent emission
to calculations improves agreements with experimental data essentially,
contribution of incoherent bremsstrahlung is essentially larger than coherent
one. (2) Inclusion of form factors of the scattered proton improves agreement
with experimental data in comparison with calculations with coherent and
incoherent contributions without form factors. (3) Sensitivity of model in
study of form factors of the scattered proton is high. This demonstrates a new
opportunity to study internal structure of protons under influence of nuclear
forces in nuclear scattering.
