31 Questions
What is the maximum displacement of the disturbance from the equilibrium position called?
Amplitude
What is the term for the highest point in a wave?
Crest
What is the term for the lowest point in a wave?
Trough
What is the term for the length of the wave between two crests or two troughs?
Wavelength
In which type of wave does the medium oscillate parallel to the direction of the wave pulse?
Longitudinal Waves
What is Compression?
Areas where the wave is closest together
In which type of wave does the medium oscillate perpendicular to the direction of the wave pulse?
Transverse Waves
What's Rarefaction?
Areas where the wave is most spread out.
Example of longitudinal wave.
Sound
Example of Transverse wave?
What's a Period? Symbol? Unit? Formula?
Period is the time in which a wave completes a full cycle (oscillation)
What's Sound?
Sound is a pressure wave caused by vibration in a medium. A vibrating particle will collide with other particles making them vibrate too.
What's Frequency? Symbol? Unit? Formula?
Frequency is the number of cycles completed in a second. Symbol: f, Unit: Hz (Hertz), Formula: f= #cycles/∆T.
What's Longitudinal wave pattern?
When vibrating particles transfer their energy to many particles.
How do High & Low pressure are caused?
By particles be squished together or far apart.
Sound waves speed in liquid, gas & s solid (from slowest to fastest)
Gas, Liquid, Solid
Warner temperatures = sound travel fast
True
What is an echo?
When sound collides with a solid surface, it reflects back. Due to how long sound traveling takes, there will be a delay.
Humans hear sound between
20 to 20,000 Hz
What's Pitch?
How we hear sound wave's frequency with our ears.
Lower the pitch = Higher the frequency
False
When does Doppler effect occur?
Occurs when the source of the wave is moving with respect to the observer.
As source approaches, waves get __________ (λ ______)
Compressed, decreases
As source passes by, waves are ____________________ (λ ______________)
Spread out, increases
What is the only thing that changes in Doppler effect?
Wavelength
What's Mach Speed?
It describes how many times the speed of sound is travelling.
What's Sonic Boom?
If an object travels at the the speed of sound, its sound waves will overlap. Air particles are highly pressurized (compressed), creating a sonic boom. This can damage trees, plants, and even shatter windows, because the frequency is very high!
What's mach cone?
When going faster than the speed of sound, a cone shape sound wave pattern called a mach cone forms.
How do noise cancellation work?
Noisecancellation headphones will remove background noise by recording the sound from its surroundings and replaying it out-of-phase (1/2 wavelength delay), causing complete destructive interference.
Infrasound?
Frequency below human hearing
Ultrasound?
Above human frequency hearing.
Study Notes
Waves and Sound
- The maximum displacement of the disturbance from the equilibrium position is called amplitude.
- The highest point in a wave is called a crest.
- The lowest point in a wave is called a trough.
- The length of the wave between two crests or two troughs is called the wavelength.
Types of Waves
- In a longitudinal wave, the medium oscillates parallel to the direction of the wave pulse.
- In a transverse wave, the medium oscillates perpendicular to the direction of the wave pulse.
- Compression is a region where the particles are close together.
- Rarefaction is a region where the particles are spread apart.
Examples of Waves
- An example of a longitudinal wave is a sound wave in a gas.
- An example of a transverse wave is a light wave.
Properties of Waves
- A period is the time taken by the wave to complete one oscillation.
- The symbol for period is T and its unit is seconds (s).
- The formula for period is T = 1/f, where f is the frequency.
- Sound is a form of mechanical wave that requires a medium to propagate.
Frequency
- Frequency is the number of oscillations or cycles per second.
- The symbol for frequency is f and its unit is Hertz (Hz).
- The formula for frequency is f = 1/T, where T is the period.
Longitudinal Wave Pattern
- In a longitudinal wave, the particles oscillate back and forth along the direction of propagation.
Pressure and Temperature
- High pressure is caused by the particles being compressed, and low pressure is caused by the particles being rarefied.
- In warmer temperatures, sound travels faster.
Echoes and Human Hearing
- An echo is a repeated sound that is reflected back to the listener.
- Humans can hear sound between 20 Hz and 20,000 Hz.
Pitch and Frequency
- Pitch is the perception of the frequency of a sound wave.
- Lower the pitch means higher the frequency.
Doppler Effect
- The Doppler effect occurs when there is relative motion between the source and the observer.
- As the source approaches, waves get shorter (λ decreases).
- As the source passes by, waves are stretched out (λ increases).
- The only thing that changes in the Doppler effect is the wavelength.
Speed of Sound and Mach Speed
- The speed of sound in liquid, gas, and solid (from slowest to fastest) is approximately 343 m/s, 1,482 m/s, and 5,960 m/s respectively.
- Mach speed is the speed of an object as a multiple of the speed of sound (M = v / v_sound).
Sonic Boom and Mach Cone
- A sonic boom is a shockwave produced when an object breaks the sound barrier.
- A mach cone is the cone-shaped shockwave produced by an object traveling at supersonic speeds.
Noise Cancellation and Infrasound/Ultrasound
- Noise cancellation works by producing a sound wave with the same amplitude but opposite phase to cancel out the noise.
- Infrasound is sound with frequencies below 20 Hz, while ultrasound is sound with frequencies above 20,000 Hz.
This quiz provides an introduction to the concept of waves, including their characteristics and types. It covers the definition of waves, their behavior, and the distinction between transverse waves and other types.
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