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Example: Two identical water waves meet head‑on. Given: Amplitude of each wave A = 2 cm, wavelength λ = 5 cm, they are in phase (phase difference = 0). Step 1: Identify the type of interference. Since the phase difference is 0, it is constructive interference. Step 2: Find the resultant amplitude. For constructive interference, A_res = A1 + A2 = 2 cm + 2 cm = 4 cm. Step 3: Determine the resultant wave height (crest to trough). Height = 2 × A_res = 2 × 4 cm = 8 cm. Step 4: State the result. The two waves combine to produce a single wave whose crests are 8 cm apart, twice as tall as each original wave. Thus, when two in‑phase water waves meet, they create a bigger wave with amplitude equal to the sum of the individual amplitudes.