5A1 Types and Characteristics of Waves

Question 1

Define:

Wave

Answer 1

Propagation of a repeating, periodic disturbance from place to place.

This disturbance transfers energy through matter or space without the movement of matter itself.

Question 2

True or false:

Waves can only transfer energy through solids.

Answer 2

False

Waves can travel through solids, liquids, and gases, depending on the type of wave.

Question 3

How is a wave typically represented graphically?

Answer 3

As a sine or cosine curve, where the x-axis represents time or distance, and the y-axis represents displacement or amplitude.

The peaks of the wave represent the maximum displacement (crest), while the troughs represent the minimum displacement (trough).

Question 4

Fill in the blank:

A(n) _______ is an instrument commonly used to visualize and measure waveforms, including amplitude, frequency, and phase.

Answer 4

oscilloscope

An oscilloscope displays waveforms on a screen, allowing detailed analysis of wave properties in real-time.

Question 5

Why are waves important in physics?

Answer 5

They explain how energy, sound, light, and radiation are transferred.

They play a key role in communication, medicine, and many natural phenomena.

Question 6

Define:

Amplitude

Answer 6

Maximum displacement of particles from their equilibrium position in a wave.

It determines the wave’s energy in mechanical waves.

Question 7

Explain the relationship between frequency and period in a wave.

Answer 7

The frequency is the reciprocal of the period: f=1/T.

Frequency is measured in Hertz (Hz), while the period is measured in seconds (s).

Question 8

True or false:

Higher frequency waves have longer wavelengths.

Answer 8

False

Wavelength decreases as frequency increases.

Question 9

Fill in the blanks:

The speed of a wave (v) is equal to the product of its ______ and ______.

Answer 9

frequency; wavelength

The formula is v=f⋅λ.

Question 10

What is the unit of measurement for frequency?

Answer 10

Hertz (Hz)

Frequency is measured in hertz, which indicates the number of cycles per second.

Question 11

What happens to the energy of a wave if the amplitude doubles?

Answer 11

The energy becomes four times greater.

Wave energy is proportional to the square of the amplitude.

Question 12

What are the formulas for the kinetic and potential energy of a wave?

Answer 12

• Kinetic Energy: KE=1/2 ρv²A² sin²(kx−ωt)
• Potential Energy: PE=1/2 ρv²A² cos²(kx−ωt)

In the equations, ρ = medium density, v = wave speed, A = amplitude, k = wave number, ω = angular frequency.

Question 13

How does light’s speed differ between air and water?

Answer 13

Light travels slower in water than in air.

This change in speed causes refraction.

Question 14

True or false:

The wavelength of a wave is the distance between consecutive crests or troughs.

Answer 14

True

This applies to transverse waves.

Question 15

What is the SI unit of wavelength?

Answer 15

Meter (m)

Wavelength represents the distance between two consecutive points in phase, such as two crests or two troughs.

Question 16

What is the formula for the wave number?

Answer 16

k= 2π/λ

λ is the wavelength. Wave number (k) indicates how many wave cycles fit into a unit length.

Question 17

Why does sound travel faster in steel than in air?

Answer 17

The particles in steel are more tightly packed, allowing faster energy transfer.

Mechanical waves move faster in solids due to stronger particle interactions.

Question 18

Define:

Transverse wave

Answer 18

A wave in which the particles of the medium move perpendicular to the direction of wave propagation.

Light waves are an example of transverse waves.

Question 19

Fill in the blank:

In a ______ wave, the medium’s particles oscillate parallel to the wave’s direction.

Answer 19

longitudinal

Examples include sound waves.

Question 20

True or false:

Sound waves are transverse waves.

Answer 20

False

Sound waves are longitudinal waves. Longitudinal waves have particle motion parallel to the wave direction.

Question 21

Why are water waves classified as both transverse and longitudinal?

Answer 21

Water particles move in circular paths, combining perpendicular and parallel motions to the wave propagation.

This is called an orbital wave motion.

Question 22

What type of wave is created by a vibrating string?

Answer 22

Transverse wave

The vibration creates perpendicular disturbances along the string.

Question 23

Define:

Compression in a longitudinal wave

Answer 23

A region where particles are close together in a longitudinal wave.

Opposite to rarefaction.

Question 24

True or false:

Earthquake S-waves are transverse.

Answer 24

True

They move the ground up and down or side to side.

Question 25

What is the difference between **P-waves** and **S-waves**?

Answer 25

* P-waves: Longitudinal, fastest, travel through solid and liquid. * S-waves: Transverse, second fastest, only travel through solids. ## Footnote Both are types of seismic waves caused by earthquakes.

Question 26

What are **Rayleigh waves**?

Answer 26

**Surface waves** that travel along the surface of solids, causing both vertical and horizontal ground motion. ## Footnote They are a type of seismic wave. Rayleigh waves are slower than body waves (P-waves and S-waves) and are responsible for most of the shaking felt during an earthquake.

Question 27

# Fill in the blank: A wave that requires a **medium** to travel through is called a \_\_\_\_\_\_\_ wave.

Answer 27

mechanical ## Footnote Examples include sound waves and water waves.

Question 28

# True or false: **Electromagnetic** waves require a medium to travel.

Answer 28

False ## Footnote Electromagnetic waves can travel through the vacuum of space.

Question 29

Explain why **mechanical waves** cannot travel through a **vacuum**.

Answer 29

They **require interactions between particles** in a medium to transfer energy, which is absent in a vacuum. ## Footnote Sound cannot travel in space for this reason.

Question 30

Provide an example of an **electromagnetic wave** and describe its application.

Answer 30

**X-rays,** used in medical imaging. ## Footnote They can penetrate soft tissue but are absorbed by bones.

Question 31

# True or false: **Mechanical waves** can be either **transverse** or **longitudinal**.

Answer 31

True ## Footnote Water waves are transverse, while sound waves are longitudinal.

Question 32

Explain why **radio signals** can travel from satellites to Earth.

Answer 32

They waves are electromagnetic and can travel through the vacuum of space. ## Footnote They do not need a medium for transmission.

Question 33

# Define: Electromagnetic spectrum

Answer 33

**Range of all types of electromagnetic radiation**, classified by their wavelengths or frequencies. ## Footnote It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Question 34

What are the **main components** of an **electromagnetic wave**?

Answer 34

1. An electric field 2. A magnetic field ## Footnote They oscillate perpendicular to each other and to the direction of wave propagation.

Question 35

What is the **speed** of **electromagnetic waves** in a vacuum?

Answer 35

The **speed of light** (approximately 3.00 × 10⁸ m/s). ## Footnote This speed is **constant** for all types of electromagnetic radiation in a vacuum, regardless of frequency or wavelength.

Question 36

How is the **energy** of an electromagnetic wave related to its **frequency**?

Answer 36

It is **directly proportional** to its frequency. ## Footnote It is given by the equation **E=h×f**, where E is the energy, h is Planck’s constant, and f is the frequency.

Question 37

What does the principle of **superposition of waves** state?

Answer 37

When two or more waves overlap, their **displacements combine** to form a resultant wave. ## Footnote This can cause constructive or destructive interference.

Question 38

What is the **phase** of a wave?

Answer 38

**Position of a point** within a wave cycle, typically measured in degrees or radians. ## Footnote Phase differences between waves determine whether they interfere constructively or destructively.

Question 39

When are two waves considered **in phase**?

Answer 39

When their crests and troughs **occur at the same time and position**. ## Footnote When waves are in phase, their amplitudes combine to form a wave with greater overall amplitude.

Question 40

# True or false: When two waves are in phase, **destructive interference** occurs.

Answer 40

False ## Footnote Waves in phase produce constructive interference.

Question 41

# Fill in the blank: When two waves are \_\_\_\_\_\_, their **peaks and troughs** align perfectly.

Answer 41

in phase ## Footnote This results in constructive interference.

Question 42

What is **constructive interference**?

Answer 42

It occurs when the compression of one sound wave **coincides** with the compression of another sound wave. ## Footnote Similar results occur with light waves when peaks coincide.

Question 43

What is an example of **superposition** in day-to-day life?

Answer 43

**Noise-canceling headphones** use destructive interference to reduce ambient sound. ## Footnote Microphones capture sound waves and generate opposite waves.

Question 44

# Define: Interference patterns

Answer 44

Result of the **superposition of two or more waves**, creating regions of constructive interference (increased amplitude) and destructive interference (reduced amplitude). ## Footnote Interference patterns provide evidence of the wave nature of phenomena, such as light in the famous double-slit experiment.

Question 45

# True or false: **Interference patterns** are observed in both sound and light waves.

Answer 45

True ## Footnote Light interference creates patterns of bright and dark fringes.

Question 46

# Define: Wave intensity

Answer 46

The **power carried by a wave per unit area**, measured perpendicular to its direction. ## Footnote It is measured in watts per square meter (W/m²).

Question 47

# True or false: **Wave intensity** increases as the **distance from the source** increases.

Answer 47

False ## Footnote Intensity decreases as the distance from the source increases due to energy dispersion.

Question 48

# Fill in the blank: Intensity is **proportional** to the square of the \_\_\_\_\_\_\_ of a wave.

Answer 48

amplitude ## Footnote Doubling the amplitude quadruples the intensity.

Question 49

What is the **formula** for wave **intensity**?

Answer 49

I=P/A ## Footnote Where I is intensity, P is power, and A is the area.

Question 50

How do you calculate the **power** of a wave?

Answer 50

P=1/2 ρvω²A² ## Footnote P∝A²; doubling the amplitude increases the power fourfold.

Question 51

How does intensity relate to **sound perception**?

Answer 51

Higher intensity results in louder sounds. ## Footnote The human ear perceives sound intensity logarithmically.

Question 52

What is a **resultant wave**?

Answer 52

The result of **combining two or more waves** or superposing waves. ## Footnote This concept is central to understanding wave behavior.

Question 53

What is the relationship between wave **intensity** and **energy transfer**?

Answer 53

Higher intensity indicates **greater energy transfer** per unit area. ## Footnote This applies to both mechanical and electromagnetic waves.

Question 54

# Define: Spherical wave

Answer 54

Wave that propagates outward in all directions from a point source, forming **spherical wavefronts**. ## Footnote Sound waves from a small speaker are an example.

Question 55

# True or false: **Plane waves** maintain parallel wavefronts as they propagate.

Answer 55

True ## Footnote Light waves from a distant laser can approximate plane waves.

Question 56

# Fill in the blank: In **spherical waves**, wave intensity decreases according to the \_\_\_\_\_\_ \_\_\_\_\_ law.

Answer 56

inverse square ## Footnote Intensity is inversely proportional to the square of the distance from the source.

Question 57

What happens to a **spherical wave** as the distance from the source increases?

Answer 57

The **wavefronts** become less curved and can approximate **plane waves** at great distances. ## Footnote This transition is useful in optics.

Question 58

How are **plane waves** useful in physics experiments?

Answer 58

They simplify wave analysis by **assuming constant phase and amplitude** across wavefronts. ## Footnote This assumption is valid in controlled conditions.

Question 59

Provide a **real-world example** of a spherical wave.

Answer 59

Sound waves from a **fire alarm** propagate as spherical waves. ## Footnote The sound spreads in all directions.

Question 60

# Define: Standing wave

Answer 60

Waves that oscillate in time but **do not move in space**. ## Footnote It is formed when two waves of the same frequency and amplitude traveling in opposite directions interfere.

Question 61

# Fill in the blank: In a standing wave, \_\_\_\_\_\_ are points where there is **no displacement**.

Answer 61

nodes ## Footnote These points remain stationary.

Question 62

# True or false: **Nodes** in a standing wave have the highest amplitude.

Answer 62

False ## Footnote **Antinodes** have the highest amplitude.

Question 63

What is the relationship between the wavelength and the length of a **string fixed** at both ends?

Answer 63

The wavelength is twice the length of the string for the fundamental frequency. ## Footnote Higher harmonics have shorter wavelengths.

Question 64

How does the formation of **standing waves** affect **resonance** in cavities?

Answer 64

Standing waves **enhance** resonance by reinforcing specific frequencies. ## Footnote This is exploited in lasers and musical instruments.

Question 65

What is the formula for the **frequency** of a standing wave?

Answer 65

f_n = nv/(2L) ## Footnote L is the length of the string, n is the number of antinodes, and v is the velocity of the waves.

Question 66

What are **harmonics** in standing waves?

Answer 66

A **set frequency** corresponding to a specific number of antinodes. ## Footnote Standing waves can only have a fixed value of frequency.

Question 67

What is the **fundamental frequency** of a **standing wave**?

Answer 67

The **lowest frequency at which a standing wave forms**; also known as the first harmonic. ## Footnote The wavelength of the fundamental is λ1=2L, where L is the length of the medium.

Question 68

What is the formula for the wavelength of the **n-th harmonic** in a standing wave?

Answer 68

λ_n= 2L/n ## Footnote n is the harmonic number, and L is the length of the vibrating medium.

Question 69

How are the **frequencies of harmonics** related to the fundamental frequency?

Answer 69

f_n =n⋅f1 ## Footnote Higher harmonic frequencies are integer multiples of the fundamental frequency f1.

Question 70

Provide an example of a **practical application** of standing waves.

Answer 70

**Microwave ovens** use standing waves to heat food. ## Footnote The antinodes deliver maximum energy for heating.