  We discuss how electromagnetic properties provide useful tests of the nature
of resonances, and we study these properties for the N*(1535) which appears
dynamically generated from the strong interaction of mesons and baryons. Within
this coupled channel chiral unitary approach, we evaluate the A_1/2 and S_1/2
helicity amplitudes as a function of Q^2 for the electromagnetic N*(1535) to
gamma* N transition. Within the same formalism we evaluate the cross section
for the reactions gamma N to eta N. We find a fair agreement for the absolute
values of the transition amplitudes, as well as for the Q^2 dependence of the
amplitudes, within theoretical and experimental uncertainties discussed in the
paper. The ratios obtained between the S_1/2 and A_1/2 for the neutron or
proton states of the N*(1535) are in qualitative agreement with experiment and
there is agreement on the signs. The same occurs for the ratio of cross
sections for the eta photoproduction on neutron and proton targets in the
vicinity of the N*(1535) energy. The global results support the idea of this
resonance as being dynamically generated, hence, largely built up from meson
baryon components. However, the details of the model indicate that an admixture
with a genuine quark state is also demanded that could help obtain a better
agreement with experimental data.

Nuclear Theory