Wave Interactions worksheet with diagrams of wave reflection at boundaries and the law of reflection.

Let’s go step by step through each question on the worksheet.

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Question 1:

> A wave front is the portion of the medium’s surface in which all particles are ________________. The front is always ________________ to the direction the wave is traveling.

Think about what a “wave front” means — it’s like the leading edge of a wave, where everything is doing the same thing at the same time. For example, if you drop a stone in water, the ripples form circles — every point on one circle is moving up or down together. That’s called being “in phase.”

Also, wave fronts move perpendicular (at right angles) to the direction the wave travels. Like ocean waves coming toward shore — the wave front is the line of breaking water, and it moves straight toward you, while the front itself runs left-to-right across your view.

So:

- First blank: in phase
- Second blank: perpendicular

Then it says: *Use dotted lines to draw the wave fronts created by these adjacent waves. Use an arrow to show the direction of the wave.*

Looking at the wavy lines shown (even though we can’t see them here), imagine two sets of curved waves next to each other. Wave fronts would be drawn as straight or curved dotted lines connecting points that are at the same part of the wave cycle — like crest to crest or trough to trough. And since the waves are moving outward from their source, arrows should point away from the center of curvature.

But since this is text-based, I’ll describe how to do it:

→ Draw dotted lines perpendicular to the direction of travel, cutting across the peaks (or troughs) of the waves.
→ Add an arrow pointing in the direction the wave is going — usually outward from the source.

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Question 2:

> The turning back of a wave at a boundary of a new medium is called ________________. If the new medium is very similar to the old, (most, little) will be transmitted and (most, little) will be reflected. For the following examples, consider the new medium to be very different from the old, so almost all of the wave will be ________________.

This is about reflection and transmission at boundaries.

When a wave hits a boundary and bounces back, that’s called reflection.

If the new medium is similar (like air to slightly denser air), most of the wave goes through → transmitted, and only a little reflects.

But if the new medium is very different (like rope tied to a wall), then almost none goes through → almost all gets reflected.

So:

- First blank: reflection
- Second: most (transmitted)
- Third: little (reflected) — wait, no! Let’s read again.

Actually, sentence says:
“If the new medium is very similar... (most, little) will be transmitted and (most, little) will be reflected.”

Similar → easy to pass through → most transmitted, little reflected

Then: “For the following examples, consider the new medium to be very different... so almost all of the wave will be ________________.”

Very different → hard to pass → mostly reflected → so blank = reflected

Now for drawing:

There are two cases:

Top diagram: Flexible Boundary

Incident pulse comes in → hits flexible end (like a ring sliding on a pole). When it reflects off a flexible boundary, the pulse flips upside-down? Wait — actually, NO!

Wait — correction:

- Fixed boundary (tied down): pulse inverts when reflected.
- Free/flexible boundary (can move freely): pulse does NOT invert — stays upright.

In top case: “Flexible Boundary” — so reflected pulse should look the same shape as incident pulse, just moving backward.

Bottom case: “Fixed Boundary” — pulse hits something rigid → reflects inverted (upside-down).

So for drawings:

→ Top: Reflected Pulse = same hump shape, arrow pointing left
→ Bottom: Reflected Pulse = flipped hump (downward bump), arrow pointing left

(You’d draw this on paper — but since we’re typing, I’m describing.)

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Question 3:

> The Law of Reflection states: Both angles are drawn from the wave to the ________________, which is ________________ to the boundary. For the following, draw the normal, the reflected wave, labeling i and r-reflection. With dotted lines, draw the wave fronts.

Law of Reflection: angle of incidence = angle of reflection.

Both angles are measured from the ray (or wave direction) to the normal — which is an imaginary line drawn perpendicular to the boundary at the point where the wave hits.

So:

- First blank: normal
- Second blank: perpendicular

Then you have to draw:

Given incoming wave (arrow hitting a slanted line representing boundary):

Step 1: At the point where the arrow touches the boundary, draw a dashed line perpendicular to the boundary — that’s the normal.

Step 2: Measure the angle between incoming arrow and normal — that’s angle i (incidence).

Step 3: On the other side of the normal, draw the reflected arrow making the same angle with the normal — label that angle r.

Step 4: Draw dotted lines perpendicular to both incoming and outgoing rays — those are the wave fronts.

Again, since we can’t draw here, I’ll tell you exactly what to do on paper.

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✔ Now let’s compile final answers clearly.

Final Answer:

1.
- in phase
- perpendicular
*(Draw dotted lines perpendicular to wave direction; add arrow showing direction of travel)*

2.
- reflection
- most
- little
- reflected
*(Top diagram: reflected pulse same shape, arrow left | Bottom diagram: reflected pulse inverted, arrow left)*

3.
- normal
- perpendicular
*(Draw normal perpendicular to boundary at impact point; reflect wave so angle i = angle r; draw dotted wave fronts perpendicular to rays)*