  In experiments on the electron linac LUE-40 of RDC "Accelerator" NSC KIPT,
the flux-averaged cross-sections $\langle{\sigma(E_{\rm{\gamma
max}})}\rangle_{\rm{exp}}$ of photonuclear reactions
${^{100}\rm{Mo}}(\gamma,n)^{99}\rm{Mo}$,
${^{27}\rm{Al}}(\gamma,x)^{24}\rm{Na}$,
${^{93}\rm{Nb}}(\gamma,n)^{92m}\rm{Nb}$,
${^{93}\rm{Nb}}(\gamma,3n)^{90}\rm{Nb}$, and
${^{181}\rm{Ta}}(\gamma,n)^{180g}\rm{Ta}$ were measured using the
$\gamma$-activation technique. The theoretical flux-average cross-sections
$\langle{\sigma(E_{\rm{\gamma max}})}\rangle_{\rm{th}}$ were computed using the
partial cross-section $\sigma(E)$ values from the TALYS1.9-1.95 codes and
bremsstrahlung $\gamma$-flux calculated using GEANT4.9.2. Two different
experimental setups were used in the experiments: an aluminum electron absorber
and a deflecting magnet to clean the bremsstrahlung $\gamma$-flux from
electrons. A comparison of the flux-average cross-sections measured for two
experimental setups was performed. The possibility of using the reactions
${^{100}\rm{Mo}}(\gamma,n)^{99}\rm{Mo}$,
${^{27}\rm{Al}}(\gamma,x)^{24}\rm{Na}$,
${^{93}\rm{Nb}}(\gamma,n)^{92m}\rm{Nb}$,
${^{93}\rm{Nb}}(\gamma,3n)^{90}\rm{Nb}$, and
${^{181}\rm{Ta}}(\gamma,n)^{180g}\rm{Ta}$ as monitors of the bremsstrahlung
$\gamma$-flux for the energy range 30-100 MeV was investigated.
