Determination of Lags Between Variations in the B, V, R, and I Bands in Active Galactic Nuclei

The lag between variations in B, V , R, and I bands for 14 active galactic nuclei has been determined. The inter-band lag scales with luminosity as L, where b ≈ 0.4− 0.5. Possible reasons for this lag and lag-wavelength and lag-luminosity relationships are discussed.