<P> In physics , interference is a phenomenon in which two waves superpose to form a resultant wave of greater , lower , or the same amplitude . Interference usually refers to the interaction of waves that are correlated or coherent with each other , either because they come from the same source or because they have the same or nearly the same frequency . Interference effects can be observed with all types of waves , for example , light , radio , acoustic , surface water waves or matter waves . </P>
<P> In physics , interference is a phenomenon in which two waves superpose to form a resultant wave of greater , lower , or the same amplitude . Interference usually refers to the interaction of waves that are correlated or coherent with each other , either because they come from the same source or because they have the same or nearly the same frequency . Interference effects can be observed with all types of waves , for example , light , radio , acoustic , surface water waves or matter waves . </P>
two waves can interfere only if they have
two waves can interfere only if they have
the same or nearly the same frequency
the same or nearly the same frequency