Consider what water waves look like when you throw a rock into a lake. These waves start at the point where the rock entered the water and travel out in all directions. When viewed from above, these waves can be drawn as shown(Figure 2), where the solid lines represent wave peaks and troughs are located halfway between adjacent peaks. Part C Now look at the waves emitted from two identical sources (e.g., two identical rocks that fall into a lake at the same time). The sources emit identical waves at the exact same time. (Figure 3) Identify whether the waves interfere constructively or destructively at each point A to D. For points A to D enter either c for constructive or d for destructive interference. For example if constructive interference occurs at points A, C and D, and destructive interference occurs at B, enter cdcc.

Figure 2 of 3 Rock acts as wave source Wave troughs Wave crests