CEM 141 -Chapter 2-Question with Correct Answers/ Verified
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Course
Cem 141
Institution
Cem 141
a continuously repeating change or oscillation of matter or a physical field in which the oscillation
travels. -️️wave
Light is a wave. It consists of oscillating electric and magnetic fields that can travel thru space. -
️️
the distance between any two adjacent identical points of a wa...
CEM 141 -Chapter 2-Question with Correct Answers/ Verified
a continuously repeating change or oscillation of matter or a physical field in which the oscillation
travels. - ✔️✔️wave
Light is a wave. It consists of oscillating electric and magnetic fields that can travel thru space. -
✔️✔️
the distance between any two adjacent identical points of a wave
- the distance btwn two adjacent high points (maxima)
- units : m or nm - ✔️✔️wavelength (λ)
the number of wavelengths of a wave that pass a fixed point in one unit of time (one second)
- units: /s or s^-1 also called hertz (Hz) - ✔️✔️frequency (ν)
equation for speed of a wave? - ✔️✔️c = λν
the speed of light? - ✔️✔️c = 3.00 x 10^8 m/s
the range of frequencies or wavelengths of electromagnetic radiation - ✔️✔️electromagnetic
spectrum
visible light extends from the ________________ end of the spectrum (has a wavelength of about
400 nm) to the _________ end of the spectrum. (wavelength = 700nm) - ✔️✔️violet
red
electromagnetic radiation is not visible to the human eye.
infrared radiation's wavelength is greater than 700 nm (greater than the λ of red light) and
ultraviolet radiation's wavelength is less than 400 nm (less than the λ of violet light) - ✔️✔️
a property in waves in which the waves spread out when they encounter an obstruction or a small
hole about the size of the wavelength - ✔️✔️diffraction
,the atoms of a solid oscillate (vibrate). A vibrating atom could only have certain energies. - ✔️✔️
6.626 x 10^-34 J x s ? - ✔️✔️Planck's constant (h)
a value that is used when describing the energy levels available to atoms and molecules. -
✔️✔️quantum numbers
the vibrational energies of the atoms are said to be QUANTIZED. ----the possible energies are limited
to certain values. - ✔️✔️
light consists of particles (photons) with energy, proportional to the observed frequency of light. -
✔️✔️E = hv
energy = Planck's constant x frequency
the ejection of electrons from the surface of a metal when light shines on it. Electrons are ejected,
however, only if the frequency of light is greater than a certain threshold value characteristic of the
particular metal.
An electron is ejected from the metal when it is struck by a single photon that has the exact amount
of energy necessary to do so (remove the electron from the attractive forces of the metal).
a photon corresponding to the threshold frequency has just enough energy, and at higher
frequencies it has more than enough energy. When the photon hits the metal, its energy is taken up
by the electron; the photon ceases to exist as a particle, its said to be absorbed - ✔️✔️photoelectric
effect
the wave and particle pictures of light should be regarded as complementary views of the same
physical entity. Neither wave nor particle view alone is a complete description of light - ✔️✔️wave
particle duality of light
SI unit for frequency? - ✔️✔️Hz (Hertz)
1/s or s^-1
Wavelength and frequency are inversely proportional. So, the _________________ the wavelength,
the _________________ the frequency, and vice versa. The equation for this is? - ✔️✔️shorter
higher
,c = wavelength x frequency
1 meter = _______ nm - ✔️✔️10 ^9
c (speed of light) = ? - ✔️✔️3.00 x 10 ^8 m/s
the light we can see with our eyes - ✔️✔️visible spectrum
types of energy to the RIGHT of the visible spectrum are LOWER in frequency and LONGER in
wavelength. what are they?
they surround us everyday and these are not harmful b/c their frequencies are so low. -
✔️✔️infrared rays, microwaves, radiowaves
types of energy to the LEFT of the visible spectrum have HIGHER frequencies and SHORTER
wavelengths. these are harmful to living organisms b/c of their extremely high frequencies. what are
they? - ✔️✔️UV rays, x-rays, gamma rays
planck's constant? - ✔️✔️6.626 x 10^-34 J⋅s
energy is ________________, meaning that it can only be transferred in individual "packets" or
(particles) of the size hv. - ✔️✔️quantized
(each energy packet is known as a quantum)
the smallest possible units by which energy can be transferred - ✔️✔️quanta
the elementary particle, or quantum, of light. Can be absorbed or emitted by atoms and molecules. -
✔️✔️photon
when a photon is ABSORBED, its energy is transferred to that atom or molecule. B/c energy is
quantized, the photon's entire energy is transferred) - ✔️✔️absorption
, when an atom or molecule loses energy, it EMITS a photon that carries an energy exactly equal to
the loss in energy of the atom or molecule. - ✔️✔️emission
This change in energy is directly proportional to the frequency of the photon emitted or absorbed.
the equation is? - ✔️✔️E = hv
how do we characterize e/m radiation? - ✔️✔️wavelength and frequency
2 models used to describe the behavior of light? - ✔️✔️wave
particle
radio waves are way _____________ than x-rays - ✔️✔️longer
the ______________ the wave the ______________ the amplitude - ✔️✔️higher
higher
the higher the _______________ the brighter the light - ✔️✔️amplitude
(m) the distance from peak to peak - ✔️✔️wavelength
(Hz, s^-1, 1/s) the # of wavefronts per second - ✔️✔️frequency
height of peaks (intensity, brightness) - ✔️✔️amplitude
increases as frequency increases, and wavelength decreases - ✔️✔️energy
_____ light has:
high frequency
high energy
short wavelength - ✔️✔️UV
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