  The diagnostic capabilities of spectral lines in far ultraviolet (FUV) and
extreme ultraviolet (EUV) wavelength range are explored in terms of their Hanle
and Zeeman sensitivity to probe vector magnetic field in the solar corona. The
temperature range covered is log$_{10}(T)=5.5-6.3$. The circular polarization
signal due to longitudinal Zeeman effect is estimated for spectral lines in the
wavelength range of 500 to 1600 \r{A}. The Stokes $V/I$ signal for a FUV line
is found to be in the order of 10$^{-4}$ for a longitudinal field strength of
10 Gauss, which further reduces to 10$^{-5}$ for wavelengths below 1200 \r{A}.
Due to such low signals, the present study aims to find combination of spectral
lines having different Hanle sensitivity but with identical peak formation
temperature to probe coronal magnetic field vector. The combination of Hanle
sensitive lines is better suited because the Hanle signals are stronger by at
least an order of magnitude compared to Zeeman signals. The linear polarization
signals due to Hanle effect from at least two spectral lines are required to
derive information on the full vector. It is found from this study that there
is always a pair of Hanle sensitive lines for a given temperature range
suitable for probing coronal vector magnetic field and they are located in
close proximity with each other in terms of their wavelength.
