Hw due 02/11

Frequency=(3.0 E8 m/s)/(6.6 E-7 m)= 4.545 E14 Hertz

Energy=h*frequency=( 4.545 E14 Hertz)*(6.6 E-34 J*s)= 3 E-19 J

Energy= 3 E-19 J

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HW due 02/07

Light is a concentration of photons.  In an atom, there are different electron levels that electrons remain in.  When the atom is in a normal state, certain electrons will encounter photons that have just the right amount of energy to allow them to jump to a higher state.  The photon is absorbed during this process.  This absorption puts an atom into what’s known as the “excited state.”  If the atom doesn’t continue to absorb photons, in order for the electron to drop down an energy level, it needs to emit a photon in a process called emission (which was the same amount of energy it took to make the electron go up an energy level).

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HW due 02/03

At every point before “white light” is interpreted as “white” in our brains, it is simply a combination of all colors.  In our eyes, there are rods and cones.  Rods exist to determine the intensity of light whereas cones exist to determine the color.  There are three cones in the eye (red, green, and blue).  They each detect wavelengths for of colors on the ROGYBV spectrum.  In order for our brains to register white light, all of the cones must be triggered at once, sending electrical messages to the brain.  This indicates that all colors and wavelengths are present.  For some reason, our brain registers the presence of all colors as being white.  Outside of our brains, white exists as the combination of every color.

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HW due 02/01

The materials that are used to build musical instruments are important because they vibrate at a specific frequency–a natural frequency.  All objects vibrate, but when the amplitudes of the vibration are large enough and the natural frequency is in the human range of hearing, the sound waves are audible.  Some objects vibrate at a single frequency and produce a pure tone (like a flute).  Others vibrate and produce more complex freqencies that have a mathematical relationship.  The result is a rich sound (like in a tuba).  For string instruments, changing the length of the strings while playing (such as with guitar strings) really affects the sound.  It shortens the string, which changes the wavelength of the instrument and with that, the sound.  For wind instruments, changing the tube is what changes the sound of the instrument.  It changes the size of the air column in the instrument, which affects the wavelength and the frequency.  Yes, the size of an instrument is an important consideration of designing said instrument.  A musician must find a material that positively affects the speed of the material (frequency) and a length that makes the sound waves the instrument produces audible.

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HW due 01/28

Sound waves, sometimes referred to as pressure waves, are mechanical waves that result from the back and forth vibrations of a particle through a medium.  The ear uses these longitudinal vibrations to determine sound.  There are two aspects of sound waves: compressions and rarefactions.  Compressions are where there is a high concentration of air particles.  Rarefactions are where there is a low concentration of air particles.  As sound waves are pushed into the outer ear, the canal gets compressed.  As the wave moves away, the pressure is immediately relieved from the ear to bring it back to a normal state.  Next, the air particles continue to move out of the ear and be sucked into the air -this is known as a rarefaction.  The back and forth motion causes us to hear.  How we differentiate sounds is by the wavelength of the period of the sound wave.

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HW due 01/26

Constructive interference:  Constructive interference is when two sinusoidal waves, having the same displacement, exactly overlap each other to form one big wave (that is double the amplitude).  It only occurs when both waves are displaced upward or both are displaced downward.

 

Destructive interference:  Destructive interference is when two interfering sinusoidal waves are displaced oppositely (one up and one down).  When they have the same displacement, one wave has a positive amplitude and the other has a negative one.  The resulting displacement of the two waves is balanced.

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HW due 01/24

Electrons have the tendency to vibrate at their own natural frequency.  When a light wave with the exact same frequency as the electron hits it, the interaction causes the electron to begin moving (while continuing to vibrate).  To do this, the electron absorbs the energy of the light wave which starts the vibrational motion.  Reflection and transmission of light waves occur when the wave frequencies do not match the electron’s vibrational frequency.  The electron picks up the frequency of the light wave and begins to vibrate much smaller and shorter than the light wave did.  Ultimately, the energy is re-emitted as a light wave.  Light waves are transmitted when the object is transparent and reflected when the object is opaque.

Color is a result of the way light hits an object.  It’s not actually there without light.  Whatever color an object does not absorb out of ROYGBIV, is the color we see with our eyes.

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