Wave anatomy diagram showing key terms such as crest, trough, amplitude, wavelength, and equilibrium line with corresponding definitions.

Let's solve this step by step.

We are given a wave diagram and a list of words to use to label parts of the wave and complete definitions. The words are:

Words to use:
- Hertz
- period
- metres
- dip
- seconds
- peak
- wavelength
- trough
- crest
- amplitude
- oscillation
- equilibrium line

---

Step 1: Label the Diagram

Looking at the wave diagram:

1. Top of the wave: This is called the crest (or peak – both are synonyms in wave terminology).
2. Bottom of the wave: This is the trough.
3. The horizontal dashed line: This is the equilibrium line (also called the rest position).
4. Distance between two consecutive crests (or troughs): This is the wavelength.
5. Vertical distance from the equilibrium line to the crest (or trough): This is the amplitude.
6. The time it takes for one full wave to pass → period, measured in seconds.
7. Number of waves per second → frequency, measured in Hertz.

Now, let’s fill in the blanks on the diagram:

- Top arrow pointing to the highest point of the wave → crest or peak
- Arrow pointing to the lowest point → trough
- Horizontal arrow across one full wave cycle → wavelength
- Vertical arrow from equilibrium to crest → amplitude
- Dashed horizontal line → equilibrium line

So, filling in the boxes:

```
[wavelength]
↑
[crest] [amplitude]
\ /
\ /
\ /
\ /
|
[equilibrium line]
|
/ \
/ \
/ \
/ \
/ \
[trough]
```

But based on the layout in your image:

- The top horizontal arrow (from crest to crest) → wavelength
- The vertical arrow from equilibrium to crest → amplitude
- The dashed line → equilibrium line
- The lowest point → trough
- The highest point → crest (or peak)

So, the labels should be:

- Top box (horizontal): wavelength
- Right vertical box (from equilibrium to crest): amplitude
- Bottom left box (dashed line): equilibrium line
- Bottom right box (lowest point): trough
- Highest point: crest (but not labeled directly; just implied)

Wait — looking at the actual structure:

From your image description:
- One box above the wave (between two crests) → wavelength
- One box pointing up from equilibrium to crest → amplitude
- One box pointing to the dashed line → equilibrium line
- One box pointing to the bottom of the wave → trough

And possibly the top of the wave is labeled as crest or peak, but it's not boxed.

So likely:

- Leftmost box (pointing to dashed line): equilibrium line
- Rightmost box (pointing to trough): trough
- Top box (horizontal): wavelength
- Middle vertical box (upward arrow): amplitude

So final diagram labels:

- Top horizontal: wavelength
- Vertical arrow (height): amplitude
- Dashed line: equilibrium line
- Lowest point: trough

(Also, the highest point could be labeled crest or peak, but no box is shown there.)

---

Step 2: Complete the Definitions

Now, fill in the blanks below the diagram:

1. ________ - the top of a wave
→ crest or peak
✔ crest or peak (both acceptable, but "crest" is more commonly used in wave diagrams)

2. ________ - the bottom of a wave
→ trough

3. ________ - the level if the wave flattened out
→ equilibrium line

4. ________ - a repeated action back and forth or up and down
→ oscillation

5. ________ - the number of waves that pass every second (measured in __________)
→ frequency (measured in Hertz)

6. ________ - the time it takes for one complete wave to pass (measured in __________)
→ period (measured in seconds)

---

✔ Final Answers:

#### Diagram Labels:
- Top horizontal arrow: wavelength
- Vertical arrow (from equilibrium to crest): amplitude
- Dashed line: equilibrium line
- Lowest point: trough

#### Definitions:

1. crest or peak – the top of a wave
2. trough – the bottom of a wave
3. equilibrium line – the level if the wave flattened out
4. oscillation – a repeated action back and forth or up and down
5. frequency – the number of waves that pass every second (measured in Hertz)
6. period – the time it takes for one complete wave to pass (measured in seconds)

---

🔍 Notes:

- "Peak" and "crest" are interchangeable here.
- "Dip" is not used — it’s less standard than "trough".
- "Metres" is not used in the definitions — it would be the unit for wavelength and amplitude, but not asked here.
- Some words like "dip", "metres" may not be used — which is fine.

✔ All required terms are used appropriately.

Let me know if you want a visual version or need help drawing it!