Physics Notes: Waves and Sound
WAVES & SOUND
Refraction waves bending when passing through different materials/medium
Doppler Effect the effect of a change in frequency, resulting from relative motion between source of wave & observer
Sound Intensity loudness, rate at which energy flows through an area perpendicular to direction of wave
Beats
2 waves of similar frequency causing interference heard as beats
Reflection
Occurs when particles bounce off one another in opposite direction
Decibel
Unit of sound intensity; compares to human’s hearing threshold (10^-12 W/m^2), more intense than that we can hear.
Draw wave crest circles around an object moving to the right & upward based on the Doppler effect.
What is the sound intensity of a speaker with a power of 40W if you are 3 meters away?
0.354W/M^2
What is the sound intensity of a speaker with a power of 20W is you are 2 meters way?
0.398W/m^2
What happens when light changes speed as it passes from one substance to another?
Refraction, the light slows down or speeds up bending through medium
Which way does a ray of light bend in reference to normal line from water to air?
Away from normal
From air into water?
Bend towards the normal
Why can dog here sound produced by dog whistle but humans not?
The pitch is out of human’s ear drum’s range
You are standing on a street corner and hear an ambulance siren. Without looking explain how you tell when the ambulance passes?
The pitch of the siren will change when the ambulance passes, according to Doppler Effect
As a result of distant explosion, an observer first senses a ground tremor, then hears the explosion. What accounts for this time lag?
Sound waves travel faster through the ground (soild) than through air, therefore we sense the ground tremor first
A bat flying towards a wall emits a chirp at 40 Hz. Is the frequency of the echo received by the bat greater than, less than or equal to 40 Hz.
Greater than 40Hz
A sound
Refraction waves bending when passing through different materials/medium
Doppler Effect the effect of a change in frequency, resulting from relative motion between source of wave & observer
Sound Intensity loudness, rate at which energy flows through an area perpendicular to direction of wave
Beats
2 waves of similar frequency causing interference heard as beats
Reflection
Occurs when particles bounce off one another in opposite direction
Decibel
Unit of sound intensity; compares to human’s hearing threshold (10^-12 W/m^2), more intense than that we can hear.
Draw wave crest circles around an object moving to the right & upward based on the Doppler effect.
What is the sound intensity of a speaker with a power of 40W if you are 3 meters away?
0.354W/M^2
What is the sound intensity of a speaker with a power of 20W is you are 2 meters way?
0.398W/m^2
What happens when light changes speed as it passes from one substance to another?
Refraction, the light slows down or speeds up bending through medium
Which way does a ray of light bend in reference to normal line from water to air?
Away from normal
From air into water?
Bend towards the normal
Why can dog here sound produced by dog whistle but humans not?
The pitch is out of human’s ear drum’s range
You are standing on a street corner and hear an ambulance siren. Without looking explain how you tell when the ambulance passes?
The pitch of the siren will change when the ambulance passes, according to Doppler Effect
As a result of distant explosion, an observer first senses a ground tremor, then hears the explosion. What accounts for this time lag?
Sound waves travel faster through the ground (soild) than through air, therefore we sense the ground tremor first
A bat flying towards a wall emits a chirp at 40 Hz. Is the frequency of the echo received by the bat greater than, less than or equal to 40 Hz.
Greater than 40Hz
A sound