The best examples of wave interference with water waves: 3 practical examples you can actually see

Three headline examples of wave interference with water waves

When people ask for examples of wave interference with water waves: 3 practical examples, I always come back to three workhorses that never disappoint:

• A ripple tank with two point sources
• Boat wakes overlapping on a lake or harbor
• Ocean waves bending and overlapping around piers and breakwaters

Each one shows the same physics—constructive and destructive interference—but at very different scales. Let’s walk through these three, then layer in more real examples that you can spot in everyday life.

Example 1: Two-point source interference in a shallow tray or ripple tank

This is the classic laboratory example of wave interference with water waves because it’s clean, repeatable, and easy to measure.

How to set it up

You don’t need a fancy ripple tank. A clear baking dish, shallow storage tub, or glass aquarium will do. Here’s a typical setup:

• Fill the tray with about 0.5–1 inch (1–2 cm) of water.
• Darken the room and shine a desk lamp sideways so the wave pattern throws a shadow on the bottom.
• Use two small vibration sources: two electric toothbrush heads, two phone vibration motors, or two small speakers with taped-on rods touching the water.
• Drive both sources at the same frequency (for example, a 10–20 Hz signal from a tone generator app feeding both speakers).

When the two sources oscillate in sync, you get nearly perfect coherent sources. The overlapping circular waves form a stationary interference pattern of bright and dark bands (or high and low ripples) across the tray.

What you’ll see

As the two circular wavefronts expand and meet, you’ll notice:

• Lines of strong waves (constructive interference) where crests meet crests and troughs meet troughs.
• Lines of almost no motion (destructive interference) where crests from one source meet troughs from the other.

These dark, nearly still lines are the water-wave version of the classic double-slit interference pattern in light.

Why this is one of the best examples

This is one of the best examples of wave interference with water waves because you can:

• Measure wavelength by freezing the pattern in a high-speed video or just using a ruler to measure the spacing between consecutive bright bands.
• Compare with theory using the path difference formula: constructive interference when the path difference is an integer multiple of the wavelength, destructive when it’s a half-integer multiple.
• Change the phase between the sources (for example, by delaying one speaker slightly) and watch the whole pattern shift.

If you’re teaching AP Physics or first-year university waves, this is a direct, visual bridge to the math of interference and superposition.

Example 2: Boat wakes overlapping on a lake or harbor

If you want more real-world examples of wave interference with water waves, just head to a marina or a busy lake on a calm day.

What to look for

Stand on a dock or pier and watch:

• Two small boats passing each other at moderate speed.
• A motorboat wake reflecting off a seawall and overlapping with the incoming wake.
• Several boats leaving a harbor in quick succession.

You’ll see V-shaped wakes spreading out from each boat. Where these wakes cross, the water surface becomes a patchwork of high and low waves.

Interference in action

In the overlapping region:

• Some lines of waves are higher and steeper than either wake alone (constructive interference).
• Some zones look surprisingly flat or confused, where the pattern is disturbed and the average height is reduced (partial destructive interference).

You can film this with a smartphone from above and then slow the footage down. Frame-by-frame, you’ll see crest-on-crest regions forming larger peaks and crest-on-trough regions flattening out.

Why this matters beyond a classroom demo

Boat-wake interference is more than a pretty pattern. It affects:

• Shoreline erosion: overlapping wakes can create unexpectedly large waves that hit docks or beaches harder than a single boat wake would.
• Small craft stability: kayaks and paddleboards feel the combined effect of multiple wakes, not just one.

Coastal and harbor engineers routinely simulate these effects with numerical wave models. Agencies like the U.S. Army Corps of Engineers publish open data and models on coastal waves and harbor design you can explore for real-world context (usace.army.mil).

Example 3: Ocean waves around piers, jetties, and breakwaters

For the third headline example of wave interference with water waves, go big: the ocean.

Where to stand

Good locations include:

• A long pier extending into the ocean
• A jetty made of rocks or concrete blocks
• A man-made breakwater protecting a harbor

Look from above if you can—on a pier or a cliff—so you get a clear view of the wave patterns.

What you’ll see

Incoming swells from the open ocean hit the structure and:

• Pass through gaps between pilings or rocks
• Diffract around ends of the structure
• Reflect from solid walls

The result is a complex interference field of:

• Curved wavefronts bending around obstacles
• Overlapping sets of waves—some from the original swell, some reflected, some diffracted
• Regions where the wave height is noticeably larger or smaller than nearby regions

On calm days with gentle, regular swell, you can often see almost textbook interference patterns behind a breakwater: alternating bands of rougher and calmer water.

Why coastal interference is a big deal in 2024–2025

With rising sea levels and more intense storms, coastal engineers are paying closer attention to how structures modify wave patterns. Interference between incident, reflected, and diffracted waves affects:

• Harbor safety for ships
• Wave loading on piers and seawalls
• Localized erosion hotspots

Organizations like NOAA provide data and models for coastal waves and storm surges (noaa.gov), and many modern design tools include interference effects between waves scattered by multiple structures.

More real examples of wave interference with water waves

We’ve covered three headline cases, but if you’re collecting real examples for teaching or lab reports, here are several more that clearly show interference.

4. Dripping faucet or dropping beads into a tray

Drop two beads or marbles into a tray of still water, a fraction of a second apart, at slightly different positions. The circular ripples from each impact will expand and overlap.

If you time your drops so that the second drop occurs while the first ripple pattern is still strong, you’ll see a clean interference pattern in the overlapping region. This is a great low-tech example of wave interference with water waves for younger students—no electronics, just timing and observation.

5. Wave reflection and standing waves in a long tank

Use a long rectangular tank or even a narrow storage bin. Generate regular waves at one end using a paddle or a motorized flapper.

As waves travel down the tank and reflect from the far wall, the incoming and reflected waves interfere. When the conditions are right—specific frequencies and water depths—you get standing waves:

• Nodes: points along the tank where the water surface barely moves
• Antinodes: points where the surface oscillates with large amplitude

Standing waves are a special case of interference between two waves of the same frequency traveling in opposite directions. They’re directly analogous to standing waves on strings or in air columns, making this one of the best examples for connecting water-wave interference with acoustics.

6. Interference between wind waves and swell

On large lakes or the open ocean, you often have:

• Local wind waves: short, choppy waves generated by nearby wind
• Swell: longer-period waves that traveled from distant storms

These two systems overlap. At some points, crests from both align, making unusually large waves; at others, a swell crest can line up with a local trough, partially canceling the surface motion.

This is not as visually clean as a ripple tank, but it’s a very real and important example of wave interference with water waves. Mariners and coastal forecasters care about these combined wave fields when predicting sea state and navigation conditions. NOAA’s National Weather Service provides real-time wave forecasts that account for multiple overlapping wave systems (weather.gov/marine).

7. Interference in wave energy converter arrays

As of 2024–2025, there’s growing interest in wave energy converters (WECs) as part of renewable energy portfolios. Arrays of floating devices or oscillating structures extract energy from ocean waves.

When you place many WECs in an array, each device scatters and radiates waves. The scattered waves from multiple devices interfere with each other and with the incoming swell, creating a complicated interference field:

• Some regions see amplified wave heights, which can help or hurt energy capture.
• Other regions are wave shadows, where energy has been partially extracted or canceled.

Researchers at universities and national labs (for example, projects cataloged by the U.S. Department of Energy’s Water Power Technologies Office, energy.gov) model these interference patterns to optimize array layouts. This is a cutting-edge, large-scale example of wave interference with water waves that directly ties into energy engineering.

8. Interference in laboratory wave basins

Many coastal engineering labs use large wave basins—indoor pools tens of feet long—with programmable wave makers along one wall. These can generate multiple wave trains with different frequencies and directions.

By running two or more wave makers simultaneously, engineers can:

• Reproduce realistic multi-directional seas, where interference produces a patchy pattern of high and low waves.
• Study how interference affects forces on scale models of offshore platforms, breakwaters, or floating structures.

This is interference on an industrial scale, but the physics is the same as the two-point source tray experiment—just with more sources and more complex statistics.

How to design your own interference experiment with water waves

If you’re building a lab or classroom activity around examples of wave interference with water waves: 3 practical examples, you can mix and match these ideas.

A solid progression looks like this:

• Start with the two-point source tray experiment for clean, textbook-style interference fringes.
• Add the long-tank standing wave setup to connect interference with resonance and nodes/antinodes.
• Finish by analyzing boat wakes or coastal interference using video footage—either your own or publicly available clips.

Key tips for success:

• Control the frequency: Use a tone generator app and small speakers or vibration motors to keep your sources in sync.
• Stabilize the camera: Tripod or clamp your phone; shaky footage makes patterns harder to see.
• Use side lighting: Low-angle light exaggerates the shadows of the ripples, making interference bands much easier to spot.

For quantitative labs, you can:

• Measure wavelength directly from still images.
• Use frame-by-frame analysis (even free apps) to measure wave speed and compare with the shallow-water wave speed formula.
• Compare observed interference band spacing with predictions from geometry and wave equations.

If you want to tie your lab write-up to academic standards or best practices for experimental design, the National Science Teaching Association (NSTA) has helpful resources for inquiry-based physics labs (nsta.org).

FAQ: Common questions about examples of wave interference with water waves

What are some simple classroom examples of wave interference with water waves?

Some of the simplest classroom-friendly examples of wave interference with water waves are:

• A shallow tray with two vibrating sources (electric toothbrushes or small speakers) creating overlapping circular waves.
• A long tank where waves reflect from the far wall to form standing waves with clear nodes and antinodes.
• Dropping two objects into still water in quick succession to see overlapping ripple patterns.

All three can be done with low-cost equipment and are easy for students to record and analyze.

Can you give an example of destructive interference with water waves?

Yes. In the two-point source tray experiment, destructive interference shows up as lines where the surface barely moves, even though waves from both sources are passing through. At those locations, a crest from one source arrives at the same time as a trough from the other, and the displacements cancel.

In the real world, a good example of destructive interference is a region behind a breakwater where two reflected wave systems overlap in such a way that the average wave height is noticeably reduced compared to nearby areas.

Are interference patterns with water waves the same idea as with light and sound?

The underlying principle—superposition—is the same. When two or more waves occupy the same region, their displacements add. For water waves, that displacement is the vertical motion of the water surface; for sound, it’s air pressure; for light, it’s the electric and magnetic fields.

So the classic double-slit interference of light, the interference of two sound waves in a room, and these examples of wave interference with water waves are all different faces of the same physics.

How do modern researchers use interference of water waves in 2024–2025?

Beyond classroom demos, interference of water waves matters in:

• Coastal engineering: designing harbors, breakwaters, and sea walls that account for overlapping waves from storms, tides, and reflections.
• Renewable energy: optimizing layouts of wave energy converter arrays so that interference patterns increase overall power capture instead of reducing it.
• Offshore structure design: predicting how complex, interfering seas load ships, oil platforms, and floating wind turbines.

These applications rely on numerical models and tank experiments that explicitly simulate interference between many overlapping wave systems.

In short, if you can recognize these examples of wave interference with water waves: 3 practical examples—the ripple tank, boat wakes, and coastal waves around structures—you’ll start seeing interference everywhere there’s water and motion. And once you see it, it’s hard to unsee: the surface is telling you, in real time, how waves add, cancel, and reshape the world around them.