Some material consisting of a collection of microscopic objects is kept at a high temperature. A photon detector capable of detecting photon energies from infrared through ultraviolet observes photons emitted with energies of0.3eV,0.5eV,0.8eV,2,0eV,2.5eV,and2.8eV. These are the only photon energies observed. (a) Draw and label a possible energy-level diagram for one of the microscopic objects, which has four bound states. On the diagram, indicate the transitions corresponding to the emitted photons. Explain briefly. (b) Would a spring–mass model be a good model for these microscopic objects? Why or why not? (c) The material is now cooled down to a very low temperature, and the photon detector stops detecting photon emissions. Next, a beam of light with a continuous range of energies from infrared through ultraviolet shines on the material, and the photon detector observes the beam of light after it passes through the material. What photon energies in this beam of light are observed to be significantly reduced in intensity (“dark absorption lines”)? Explain briefly.

Short Answer

Expert verified

(a) Ground state,0.3eV,0.8eV,and2.8eV

(b) No

(c)0.3eV,0.8eV,and2.8eV

Step by step solution

01

Identification of the given data

The given data can be listed below as-.

The photon energies detected by the photon detector areE1=0.3eV,E2=0.5eV,E3=0.8eV,E4=2.0eV,E5=2.5eV,E6=2.8eV

02

Significance of the energy of the photon

The photon’s energy is equal to the product of the Planck’s constant and the frequency of the photon.

The expression for the energy of the photon is given as follows,

E=hv

Here, h is the Planck’s constant and v is the frequency.

03

Determination of the energy-level diagram for one of the microscopic objects

The energy-level diagram of the microscopic objects is shown as follows,

During the energy exchange E=hv, the electrodes mainly move from one orbit to another. The absorption layers mainly consist of the ground state,E1=0.3eV,E3=0.8eV,andE6=2.8eV due to the passing of the light via material at a low temperature.

Thus, the absorption layers mainly consist of the ground state , E1=0.3eV,E3=0.8eV,andE6=2.8eVdue to the passing of the light via the material at a low temperature.

04

Determination of the suitability of a spring-mass model for microscopic objects

The spring-mass system mainly works as a simple oscillator that has evenly spaced levels of energy and not suitable for the microscopic objects.

Thus, a spring-mass model may not be good for these microscopic objects.

05

Determination of the photon energies in the beam of light that is observed to be reduced significantly in intensity

From the energy-level diagram, it is evident that there are mainly three types of photon energyin the beam of light are reducingthat includes highest-energy, second highest energy, and the lowest energy dark. Hence, from the energy level diagram, the values are , E6=2.8eV,E3=0.8eV,andE1=0.3eVrespectively.

Thus, the photon energies in this beam of light that are observed to be reduced significantly in intensity are ,E6=2.8eV,E3=0.8eV,andE1=0.3eV.

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Most popular questions from this chapter

N=1 is the lowest electronic energy state for a hydrogen atom. (a) If a hydrogen atom is in a state N=4, what is K+U for this atom (in eV)? (b) The hydrogen atom makes a transition to state N=2, Now what is K+U in electron volts for this atom? (c) What is energy (in eV) of the photon emitted in the transition from level N=4 to N=2? (d) Which of the arrows in figure 8.40 represents this transition?

Assume that a hypothetical object has just four quantum states, with the energies shown in Figure 8.43.

(a) Suppose that the temperature is high enough that in a material containing many such objects, at any instant some objects are found in all of these states. What are all the energies of photons that could be strongly emitted by the material? (In actual quantum objects there are often “selection rules” that forbid certain emissions even though there is enough energy; assume that there are no such restrictions here.) (b) If the temperature is very low and electromagnetic radiation with a wide range of energies is passed through the material, what will be the energies of photons corresponding to missing (“dark”) lines in the spectrum? (Assume that the detector is sensitive to a wide range of photon energies, not just energies in the visible region.)

A hot bar of iron glows a dull red. Using our simple ball-spring model of a solid (Figure 8.23), answer the following questions,explaining in detail the processes involved. You will need to make some rough estimates of atomic properties based on prior work. (a) What is the approximate energy of the lowest-energy spectral emission line? Give a numerical value. (b) What is the approximate energy of the highest-energy spectral emission line? Give a numerical value. (c) What is the quantum number of the highest-energy occupied state? (d) Predict the energies of two other lines in the emission spectrum of the glowing iron bar. (Note: Our simple model is too simple-the actual spectrum is more complicated. However, this simple analysis gets at some important aspects of the phenomenon.)


Assume that a hypothetical object has just four quantum states, with the following energies:

-1.0eV(third excited state)

-1.8eV(second excited state)

-2.9eV(first excited state)

-4.8eV(ground state)

(a) Suppose that material containing many such objects is hit with a beam of energetic electrons, which ensures that there are always some objects in all of these states. What are the six energies of photons that could be strongly emitted by the material? (In actual quantum objects there are often “selection rules” that forbid certain emissions even though there is enough energy; assume that there are no such restrictions here.) List the photon emission energies. (b) Next, suppose that the beam of electrons is shut off so that all of the objects are in the ground state almost all the time. If electromagnetic radiation with a wide range of energies is passed through the material, what will be the three energies of photons corresponding to missing (“dark”) lines in the spectrum? Remember that there is hardly any absorption from excited states, because emission from an excited state happens very quickly, so there is never a significant number of objects in an excited state. Assume that the detector is sensitive to a wide range of photon energies, not just energies in the visible region. List the dark-line energies.

When starlight passes through a cold cloud of hydrogen gas, some hydrogen atoms absorb energy, then reradiate it in all directions. As a result, spectrum of the star shows dark absorption lines at the energies for which less energy from the star reaches us. How does the spectrum of dark absorption lines for very cold hydrogen differs from the spectrum of bright emission lines from very hot hydrogen?

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