Wave Behavior

Reflection

The law of reflection: The waves will always reflect in which the angle that they approach the barrier equals the angle they reflect off the barrier.
Reflection of Waves in Physics
The reflection video shows the difference of the two types of reflection in waves. The first type is called fixed, which means the end of the wave is closed. The second type of reflection is called free, which means the end of the wave is open. In the video, it also explains the properties of each type of reflection, including the pattern of the crest and troughs, and out of phase and in phase. When a wave hits a fixed end, it comes back out of phase (which means its not simultaneous). When a wave hits an open end, it comes back in phase (which means it is simultaneous).
The article thoroughly explains the law of reflection with various examples, and diagrams. The examples includes an oscillator attached to a linear object and how that reflects. The diagrams display the before and after of the law of reflection. The article also explains the difference between the reflection off of both straight and curved surfaces. The differences between the two include direction and and the energy being carried. In the end, the articles states that reflection involves the change of the wave direction when they bounce off a barrier.

Refraction

The refraction of waves involves the change of the waves as they pass through different mediums.
Physics Lecture - 46 - Wave Refraction
The refraction video primarily focuses on the refraction of sound waves. The video discusses how sound travels at a faster rate in warm air than in cool air. This is possible because due to how the air molecules collide with each other. It is also faster for sound waves to travel through water due to water molecules to combine with each other to transfer the sound. In the end, the video defines refraction as the bending of a wave.
The article define refraction as a change in direction of waves when passing through a barrier. It also states that refraction involves the bending of waves, along with the change of speed and wavelength. The speed of the wave depends on the medium the wave is traveling through.

DIFFRACTION

The change the wave experiences when it travels through an opening or around a barrier in which it travels.
Physics - Waves - Diffraction
The video defines diffraction as waves that pass through a gap or object. The video explains the smaller the gap the wave passes through, a greater diffraction will be displayed. If the gap is large, you will see very little diffraction in the waves. To conclude, diffraction best occurs when the wavelength is equivalent to the size of the gap.
The article defines diffraction as the change in a wave while passing through a gap or around a barrier. The article focuses on an example of diffraction in water waves. To conclude, diffraction is the bending of waves around obstacles and openings. The amount of diffraction increases with an increasing wavelength.

CONSTRUCTIVE INTERFERENCE

One type of interference that happens on any location along the same medium where the two different overlapping waves have a displacement in the same direction.
Wave Interference
The video first explains that interference, in general, is when two different waves overlap each other.

(This is the section that solely explains constructive interference)

The video draws two different waves and displays constructive inference as when the "peaks" of both waves match, and the "valleys" of both waves match as well. By this happening, the two overlapping waves combine to form one large wave.

The above article explains constructive interference as two waves having both upward displacement. Constructive interference can occur at any location where there can be upward displacement among the waves. In the end, constructive interference can be explained as the two overlapping waves having displacement in the same direction.

DESTRUCTIVE INTERFERENCE

When two waves overlap on one another to form displacement in the opposite direction.
Wave Interference
The video first explains that interference, in general, is when two different waves overlap each other.

(This is the section that solely explains destructive interference)

Then, the video displays destructive interference with two overlapping waves with a drawing. However, the way destructive interference overlaps compared to constructive interference is different. Destructive interference, overlaps by the "peaks" matching the "valleys" and vice versa. Because of this, destructive interference actually in the end, forms no wave at all. The two waves cancel out, and later equal 0.

The article explains in detail how the two waves during destructive interference cancel each other out, and not necessarily "destroy" each other. The waves cancel out because when they align, the balance each other by the downward pull of each wave. In the end, when the two wave meet, neither of the waves alter because of the displacement.

RESONANCE

Resonance is when one object vibrates at the same neutral frequency causes a second object to vibrate as well.
Physics Lecture - 45 - Wave Resonance
The video begins to explain resonance by telling us what natural frequency is: the tendency for objects to vibrate. Then, the video defines resonance as the scenario when there are two objects Object A and Object B, and the vibration of Object A causes Object B to vibrate, at its natural frequency.
The article above mentions how natural frequency is incorporated into resonance. Natural frequency relates to resonance because natural frequency represents many standing wave patterns in objects. The only way resonance is possible is due to the natural frequency of the first object to cause the second object to vibrate.

DOPPLER EFFECT

The change of the frequency of a wave due to the relative motion between the source of the wave and the person observing it.
The Doppler Effect: what does motion do to waves?

The video explains the doppler effect displaying how the source of the waves moves its original location. In the direction the source is moving, the waves condense, and behind the source, the waves separate. The condensed waves towards the observer have a higher frequency. If the condensed waves are moving away from the observer, they have a lower frequency.

The above article notes along with what the doppler effect itself, the effect does not happen due to an actual change in the frequency of the source. In the end, the article explains the doppler effect as an apparent shift in frequency for a sound wave produced by a moving source.

BEATS

The oscillation of high and low frequency of volume.
Beats Physics
The video demonstrates a short lab of two different tuning forks. One tuning fork was placed in ice, the other placed on a flame. At the end of the lab, you can tell the difference of frequencies. To conclude, beats is defined as "a rhythmic interference of two frequencies.
(section "Beat Frequency")

The article defines beats as "the rate at which the volume is heard to be oscillating from high to low volume." The article then explains the common labs of tuning forks and their beats.