Understanding Wave Motion and Energy Transfer

• Waves play a role in transferring energy
• Wave motion is the movement resulting from the vibration of medium particles in a specific direction
• There are different types of waves, and some concepts are related to wave motion and their properties

The Role of Waves in Transferring Energy

• A wave is a disturbance that propagates and transfers energy in the direction of propagation
• Dominoes transfer energy when they fall, without changing their position in the line
• Tuning forks generate energy that transfers as sound waves which then vibrate candle flames

The Concept of Wave Motion

• Wave motion involves medium particles vibrating without leaving their place
• A wave motion is a movement resulting from the vibration of the medium particles at a certain moment in a direction
• The line of wave propagation refers to the direction in which the wave moves

Types of Waves

• Waves are classified based on the direction of vibration of medium particles relative to the direction of propagation, and the ability to propagate and transfer energy

Transverse and Longitudinal Waves

• In transverse waves, particles vibrate in a direction perpendicular to wave propagation (crests and troughs)
• In longitudinal waves, particles vibrate along the direction of wave propagation (compressions and rarefactions)
• During wave propagation, medium particles vibrate around rest positions
• Transverse waves: medium vibrates perpendicular to wave propagation direction
• Longitudinal waves: medium vibrates along wave propagation direction.

Wave Properties

• Wave Motion: Periodic motion as result of medium particles vibrating at a certain moment
• Line of Wave Propagation: the direction the wave travels
• Transverse Wave: disturbance where medium particles vibrate perpendicular to wave propagation direction
• Longitudinal Wave: disturbance where medium particles vibrate along wave propagation direction

Wave Formation

• Transverse waves form from crests and troughs
• Longitudinal waves form from compressions and rarefactions
• Crest: highest point of particles in transverse wave
• Trough: lowest point of particles in transverse wave
• Compression: area in longitudinal wave where particles have highest density/pressure
• Rarefaction: area in longitudinal wave where particles have lowest density/pressure
• Crest of transverse wave = center of compression of longitudinal wave
• Trough of transverse wave = center of rarefaction of longitudinal wave

Electromagnetic and Mechanical Waves

• Electromagnetic Waves: Don't need medium to travel, propagate through vacuum, all transverse (e.g., light, infrared, radio)
• Mechanical Waves: Need medium to travel, don't propagate through vacuum. Can be transverse (water waves) or longitudinal (sound waves)
• Electromagnetic waves propagate by velocity = 3 x 108 m/sec in vacuum, but velocity decreases when transferring in media
• Mechanical waves velocity is much slower in media
• Radio waves are transverse electromagnetic waves due to particle vibration perpendicular to wave propagation

Wave Concepts and Properties

• Light from lightning (electromagnetic) is seen before thunder (mechanical) because electromagnetic velocity is greater
• Solar explosions light is visible but sound isn't audible because sound needs a medium, but light doesn't
• Common concepts of properties include wavelength, wave amplitude, wave velocity and wave frequency
• Wavelength (λ): For transverse, distance between two crests/troughs. For longitudinal, distance between two compressions/rarefactions. Measuring unit is "metre."
• Wavelength of transverse wave is 2 multiplied the horizontal distance between successive crest and trough
• Wavelength of longitudinal waves are 2 multiplied by the distance between the center of successive compression and rarefaction
• Wavelength equals the distance covered by waves divided by the number of waves
• Wave Amplitude: Maximum displacement of medium particles from rest position, measuring unit is "meter."
• Wave amplitude: The vertical distance between the crest and trough of a wave divided by 2
• Wave Velocity (V): Distance covered by wave in one second, measured in "metre per second (m/s)."
• Wave velocity (V) equals distance covered by wave in meters divided by time in seconds
• Wave velocity is constant in the same medium, different from one medium to another
• Sound velocity: solids > liquids > gases (air)
• Velocity of sound waves through air is 340 m/s
• Velocity of sound waves through water is 1500 m/s
• Velocity of sound waves through wood is 1850 m/s
• Wave Frequency (F): Number of complete waves produced from source in one second, measures in "Hertz."
• Wave frequency equals the number of complete waves divided by time in seconds
• The periodic time of the wave is the time taken to make one wave

Laws of Wave Propagation

• The relationship between wave velocity (V), frequency (F) and wavelength (λ)
• Wave velocity (V) equals frequency (F) multiplied by wavelength (λ)
• Frequency (F) is inversely proportional to wavelength (λ) in the same medium
• Wave velocity (V) is directly proportional to frequency (F) at constant wavelength (λ)
• Wave velocity (V) is directly proportional to wavelength (λ) at constant frequency (F)