  The purpose of the Cosmic Background Radiation (CBR) experiments is to
measure the temperature anisotropy via the autocorrelation function. The
partial wave $l_1$ corresponding to the first Doppler peak caused by
baryon-photon oscillations at the surface of last scattering depends on the
present density $\Omega_0$ and the cosmological constant contribution
$\Omega_{\Lambda}$. We discuss this dependence on the basis of perspicuous
figures.
