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Fundamentals Of Physics
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Short Answer

Figure 39-29 a shows a thin tube in which a finite potential trap has been set up where V2=0 V. An electron is shown travelling rightward toward the trap, in a region with a voltage of V1=-9.00 V, where it has a kinetic energy of 2.00 eV. When the electron enters the trap region, it can become trapped if it gets rid of enough energy by emitting a photon. The energy levels of the electron within the trap are E1=1.0,E2=2.0, and E3=4.0 eV, and the non quantized region begins at E4=-9.0 eVas shown in the energylevel diagram of Fig. 39-29b. What is the smallest energy such a photon can have?

The energy of the photon is 7eV.

See the step by step solution

Step by Step Solution

Step 1: Introduction:

An electron is shown travelling rightward toward the trap, in a region with a voltage V1=-9.00 V, where it has a kinetic energy of 2.00 eV.

Step 2: Determine the energy of the photon:

The electron losses some energy when it jumps from the quantized region to the non-quantized region. The energy of the photon is the sum of the kinetic energy and the potential energy, the potential energy is equal to the difference between the third and fourth levels.

The kinetic energy is 2 eV therefore, the energy of the photon is,

E=K+PE =K+E

Since, the change in energy is equal to E4-E3.

Substitute E4-E3 for E in the above equation.

E=K+E4-E3

Substitute 2 eV for K, 9 eV for role="math" localid="1661767190577" E4 and 4 eV for E3 in the above equation.

E=2 eV+9 eV-4 eV =7eV

Hence, the energy of the photon is 7 eV.

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