3D1 Wave Phenomena

Question 1

What are the four basic behaviors, or phenomena, that can be observed when studying waves?

Answer 1

• Reflection
• Refraction
• Diffraction
• Interference

These phenomena apply to all types of waves, including sound, light, and water waves.

Question 2

What is a wave?

Answer 2

A disturbance that carries energy.

Waves can be mechanical (requiring a medium, like sound waves) or electromagnetic (not requiring a medium, like light waves).

Question 3

What is the basic principle behind an echo?

Answer 3

It is caused by the reflection of sound waves off a surface back to the listener.

The time delay between the original sound and the echo can help determine the distance to the reflecting surface.

Question 4

What is scattered reflection?

(also called diffuse)

Answer 4

It refers to waves that are reflected off a rough surface and travel in various directions.

Scattering is why objects appear the same color from different angles but can have different intensities.

Question 5

Define refraction.

Answer 5

The bending of a wave as it travels from one material into another.

Question 6

How does refraction create an optical illusion with a straw in water?

Answer 6

Light waves bend as they move from air to water, making the straw appear bent.

This effect occurs because light travels at different speeds in air and water.

Question 7

What is diffraction?

Answer 7

The movement of waves around objects.

Question 8

What is wave interference?

Answer 8

It occurs when two or more waves combine, creating a larger wave or canceling each other out partially or completely.

Interference can be constructive (waves add up) or destructive (waves cancel out).

Question 9

How do noise-canceling headphones use the principle of interference?

Answer 9

They use destructive interference to cancel out sound waves, making certain sounds inaudible.

These headphones have microphones that pick up external noise and then generate sound waves with the opposite phase.

Question 10

How do waves impact our basic senses?

Answer 10

• Visible light waves allow us to see.
• Sound waves allow us to hear.

Other types of waves, such as infrared and ultraviolet light, can also affect our senses indirectly.

Question 11

How do waves contribute to medical imaging?

Answer 11

Waves, such as sound waves, are used in ultrasound imaging systems to create images of the inside of the body.

Ultrasound uses high-frequency sound waves that reflect off tissues to create an image.

Question 12

Why can you still hear someone even if they are blocked by an object?

Answer 12

Due to diffraction, sound waves bend around objects and reach your ears.

Question 13

Distinguish between the compression and rarefaction phases of a sound wave.

Answer 13

• During compression, molecules in the medium are pressed together, increasing pressure.
• During rarefaction, molecules in the medium spread apart, decreasing pressure.

Question 14

What are the typical mediums through which sound waves travel?

Answer 14

Typically through air or water.

Sound can also travel through solids, often faster than in air or water.

Question 15

How does clapping hands produce sound?

Answer 15

It causes a brief intense compression of air molecules, followed by rarefaction, which propagates outward as sound waves.

Question 16

At what speed does sound travel at sea level in air and underwater?

Answer 16

1. Sea level in air: Approximately 760 mph
2. Underwater: Approximately 3,350 mph.

Sound speed varies with temperature, salinity, and pressure in water.

Question 17

What three main characteristics do sound waves have?

Answer 17

• Wavelength
• Frequency
• Amplitude

These characteristics determine the pitch and loudness of the sound.

Question 18

What is meant by the ‘frequency’ of a wave.

Answer 18

The number of waves that pass a point per unit time.

Question 19

How is pitch determined in a sound wave?

Answer 19

By the wavelength and frequency of the sound wave.

Higher frequency (shorter wavelength) sounds are perceived as higher pitch.

Question 20

How is volume or loudness determined in a sound wave?

Answer 20

By the amplitude of the sound wave.

Question 21

What type of wave are sound waves classified as?

Answer 21

Longitudinal waves.

In longitudinal waves, the displacement of the medium is parallel to the direction of wave propagation.

Question 22

How do longitudinal waves travel?

Answer 22

By vibrating in the same direction as their propagation.

Question 23

What are infrasonic waves?

Answer 23

These are sound waves with frequencies below 20 Hertz, which are too low for humans to hear.

These waves can be produced by natural events like earthquakes and volcanic eruptions.

Question 24

Name three applications of ultrasonic waves.

Answer 24

• Ultrasound machines in medical imaging.
• Sonar systems for underwater detection.
• Ultrasonic cleaning for removing dirt and grease.

Ultrasonic waves have frequencies above 20,000 Hertz, which are above the range of human hearing.

Question 25

What phenomenon allows dolphins and bats to navigate their environment using sound waves?

Answer 25

Echolocation

They emit sound waves and listen for the echoes to locate objects.

Question 26

What visual representation is often used to display sound waves, despite their true nature as longitudinal waves?

Answer 26

On horizontal line graphs, as if they were transverse waves.

This is for convenience in visualizing changes in amplitude and frequency.

Question 27

What is the relationship between the wavelength of a sound wave and its pitch?

Answer 27

A longer wavelength corresponds to a lower pitch, while a shorter wavelength corresponds to a higher pitch.

This inverse relationship is due to the frequency of the wave.

Question 28

What is the term for the physical length from one point of compression to the next in a sound wave?

Answer 28

Wavelength

Wavelength is typically measured in meters (m).

Question 29

What is the function of the eardrum in hearing sound waves?

Answer 29

It detects the wavelength, frequency, and amplitude of sound waves, allowing us to perceive pitch and volume.

Vibrations of the eardrum are transmitted to the inner ear, where they are converted to neural signals.

Question 30

How do sonar systems use sound waves to detect objects underwater?

Answer 30

They broadcast sound waves and listen for their reflection to detect the presence, size, and distance of objects underwater.

This technique is similar to echolocation used by dolphins and bats.

Question 31

What kind of waves are visible on the ocean’s surface, and how do they differ from sound waves?

Answer 31

Waves on the ocean’s surface are transverse waves, which travel up and down, unlike sound waves, which are longitudinal and travel through compressions and rarefactions.

Question 32

What is light from a scientific standpoint?

Answer 32

It is electromagnetic radiation that can be detected by the human eye.

The visible spectrum of light ranges from approximately 400 to 700 nanometers in wavelength.

Question 33

What is a photon and how do they travel?

Answer 33

It is a packet of electromagnetic energy, which travel as particles but exhibit wave-like properties.

This dual nature is described by wave-particle duality.

Question 34

Is light considered matter?

Answer 34

No.

Light is not matter; it is a stream of photons transmitting electromagnetic radiation.

Light does not have mass or occupy space.

Question 35

Can electromagnetic waves, including light, travel through a vacuum?

Answer 35

Yes.

Unlike mechanical waves, electromagnetic waves do not require a medium.

Question 36

What is Albert Einstein’s famous equation that includes the speed of light (C)?

Answer 36

E = mc²

E stands for energy: This represents the total energy of an object.
m stands for mass: This is the mass of the object.
c stands for the speed of light: This is a constant value, approximately 3×10^8 m/s.

Question 37

What is an excited atom?

Answer 37

An atom with electrons that have moved to a higher energy level.

Electrons gain energy to move to excited states and release energy when they return to lower states.

Question 38

What is the ground state of an atom?

Answer 38

The lowest possible level of electron energy.

Question 39

What can matter do with light?

Answer 39

It can emit, absorb, transmit, reflect, or scatter light.

These interactions are fundamental to processes like vision, photosynthesis, and various technologies.

Question 40

What is emission in the context of light and matter interaction?

Answer 40

It is when matter emits light.

Emission occurs when excited electrons return to lower energy levels, releasing energy as light, such as the filament in a light bulb.

Question 41

What is absorption in light and matter interaction?

Answer 41

It is when matter absorbs light, converting it into heat energy.

Absorption occurs when photons transfer energy to electrons, causing them to move to higher energy levels.

Question 42

What field studies the interaction between light emission, absorption, and matter?

Answer 42

Spectroscopy.

Spectroscopy is used in various fields, including chemistry, physics, and astronomy, to analyze the composition and properties of substances.

Question 43

What is wave-particle duality?

Answer 43

The concept that photons can behave like both a wave and a particle depending on the situation.

This principle is a cornerstone of quantum mechanics.

Question 44

What aspect of light’s behavior did Albert Einstein’s theory contribute to?

Answer 44

The understanding of wave-particle duality, where light can exhibit properties of both waves and particles.

Question 45

What discovery did Albert Einstein make in 1905 related to light?

Answer 45

He postulated that light should be treated as both a particle and a wave.

Question 46

Can electrons exhibit wave-particle duality?

Answer 46

Yes, but they often behave more like particles, while photons often exhibit more wave-like behavior.

Question 47

How does an electron’s distance from the nucleus affect its binding energy?

Answer 47

Electrons closer to the nucleus have higher binding energy and are more tightly bound.