Planck’s Equation Practice Problems - Weebly



Quantum BeginningWhat is classical Physics?Draw an EMR Wave.1270035369500RegionWavelength (meters)Frequency (Hz)Energy (eV)Radio> 1.0 x 10-1< 3 x 109< 10-5Microwave1.0 x 10-1 - 1.0 x 10-43 x 109?- 3 x 101210-5?- 0.01Infrared1.0 x 10-4- 7 x 10-73 x 1012?- 4.3 x 10140.01 - 2Visible7 x 10-7?- 4 x 10-74.3 x 1014?- 7.5 x 10142 - 3Ultraviolet4 x 10-7?- 10-97.5 x 1014?- 3 x 10173 - 103X-Rays10-9?- 10-113 x 1017?- 3 x 1019103?- 105Gamma Rays< 10-11> 3 x 1019> 105What is a blackbody?What happens as the blackbody continuously absorbs EMR? According to classical physics, what would happen upon the release of this absorbed EMR?If we are bombarded with UV radiation, do we emit UV radiation? Why or why not? What do we emit?In solving our Blackbody Radiation problem, what did Plank suggest was happening to the atoms that were absorbing radiation? Energy of Vibration and Photon’s Equationwhere:E =n = h = f =Is distance a scalar or a vector? _______ _________________What is an electron volt and what is its unit?Joules and eV example:Convert 5 Joules into an electron volt. Draw the electron excitation example. What is the relationship between Ef and Ei with regards to the energy of a photon Ephoton.Planks Equation where:E = h = f = Example #1Determine the smallest amount of energy from a light source that emits light at a frequency of 4.50 x1014 Hz. Example #2 Determine the minimum energy transferred by a light source with a 212 nm wavelength in electron volts.With respect to Plank and Blackbody Radiation, what did Einstein suggest regarding light?Example #3 You buy a laser at the store and read on the label that it has a frequency of 4.38 x 1015 Hz. The label also says that it runs at 4.06 mW (miliwatt). Determine how many photons it can release in one second. Energy into ev – one more way to use an eV with energyE = hf E = hc/λ convert the ‘hc’ into electron volts.hc = (6.626 x 10-34 J/Hz)(2.998 x 10 8 m/s)( 1 ev ) (109nm) 1.602 x 10 -19J 1 mhc = 1240 ev nmE = 1240 ev nm λ Example #4What is the energy of a 200 nm, 700 nm, and a 1400 nm wavelength in eV? What happens to the Energy as the wave length gets larger?Assignment: Page 734 Q 1 – 3 and Handout Questions Planck’s Equation Practice Problems Equations and constants: E = h and E = hc/E = energy of one photon with a frequency of c = f c/ = fc = speed of light = 3.0 x 108 m/s (meters per second)h = Planck’s constant = 6.63 x 10-34 J-s = wavelength in metersf = frequency in Hz (waves/s or 1/s or s-1)n = number of photons (energy level)A photon has a frequency () of 2.68 x 106 Hz. Calculate its energy. Ans: E = 1.78 x 10-27 J Calculate the energy (E) and wavelength () of a photon of light with a frequency () of 6.165 x 1014 Hz.Ans: E = 4.1 x 10-19 J = 4.87 x 10-7 m Calculate the frequency and the energy of blue light that has a wavelength of 400 nm(h = 6.62 x 10-34 J-s).Ans: f = 7.5 x 1014 Hz E = 4.97 x 10-19 J Calculate the wavelength and energy of light that has a frequency of 1.5 x 1015 Hz.Ans: = 2.0 x 10-7 m E = 9.95 x 10-19 J A photon of light has a wavelength of 0.050 cm. Calculate its energy.Ans: E = 3.98 x 10-22 J Calculate the number of photons having a wavelength of 10.0 m required to produce 1.0 kJ of energy. Ans: 5.0 x 1022 photonsCalculate the total energy in 1.5 x 1013 photons of gamma radiation having = 3.0 x 10-12 m.Ans: 1.0 JCalculate the energy and frequency of red light having a wavelength of 6.80 x 10-5 cm.Ans: E = 2.92 x 10-19 Jf = 4.4 x 1014 HzThe wavelength of green light from a traffic signal is centered at 5.20 x 10-5 cm. Calculate the frequency.Ans: = 5.77 x 1014 Hz. Calculate the frequency of light that has a wavelength of 4.25 x 10-9m. Identify the type of electromagnetic radiation.Ans: f = 7.1 x 1016 Hz.UV radiationThe wavelength of a ruby laser is 650 nm. If the power of the laser is 1.5 W, how many photons are coming out of the laser every second? Ans: n 18 4.9 ×10 photons ................
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