19-8 Beats(节拍) reviously, we have considered the interference in space · Now we sha! discuss“ interference in time We consider two waves which have nearly the same frequency. AP(1)=△PnSn1t △P2(t)=△ p sin a2t We have chosen the phase constants to be zero, and same amplitudes19-8 Beats (节拍) • Previously, we have considered the “interference in space”. • Now we shall discuss “interference in time”. • We consider two waves which have nearly the same frequency. P t P t 1 m 1  ( ) =  sin  P t P t 2 m 2  ( ) =  sin  ( ~ ) 1 2 We have chosen the phase constants to be zero, and same amplitudes