1. In a system of two conducting wires separated by a small distance L, an electron can potentially tunnel across a potential difference (air gap) between the wires. Assuming the difference Uo - E = 0.25 eV, and the probability of an electron tunneling across the potential barrier is .02%, what is the length of the gap? If the difference is 0.75 eV, how much smaller will the gap have to retain the same tunneling probability?
1. In a system of two conducting wires separated by a small distance L, an electron can potentially tunnel across a potential difference (air gap) between the wires. Assuming the difference Uo - E = 0.25 eV, and the probability of an electron tunneling across the potential barrier is .02%, what is the length of the gap? If the difference is 0.75 eV, how much smaller will the gap have to retain the same tunneling probability?
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![**Quantum Mechanics Problem: Tunneling Probability Across a Potential Barrier**
1. **Problem Description:**
- **System Setup:** Consider a system consisting of two conducting wires separated by a small distance \( L \). An electron has the potential to tunnel across this separation, also known as the air gap, by overcoming a potential difference.
- **Given Conditions:**
- The potential difference between the wires is denoted by \( U_0 - E = 0.25 \) eV.
- The probability of an electron successfully tunneling across this potential barrier is 0.02%.
- **Questions to Address:**
- What is the length of the gap, \( L \)?
- If the potential difference is increased to 0.75 eV, by how much must the gap be reduced to maintain the same tunneling probability?
**Conceptual Framework:**
- **Quantum Tunneling:** This phenomenon allows particles, such as electrons, to pass through a potential barrier that would be insurmountable according to classical physics. The probability \( P \) of tunneling is closely related to the height and width of the barrier.
- **Probability Calculation:**
- The tunneling probability \( P \) is often expressed in terms of the barrier properties and can be represented as:
\[
P \propto e^{-2 \kappa L}
\]
where \( \kappa \) is the decay constant given by:
\[
\kappa = \sqrt{\frac{2m(U_0 - E)}{\hbar^2}}
\]
Here, \( m \) is the mass of the electron and \( \hbar \) is the reduced Planck's constant.
- **Adjusting the Barrier:**
- If the potential difference changes, the decay constant \( \kappa \) and the required gap \( L \) must be adjusted accordingly to keep the tunneling probability constant.
**Graph and Diagram Explanation:**
- No graphs or diagrams are available in the provided text. However, if a graph were included, it might illustrate the relationship between the potential barrier height (\( U_0 - E \)), the gap distance (\( L \)), and the tunneling probability (\( P \)). A typical representation might show an exponential decay of tunneling probability with increasing barrier width and height.
This problem effectively integrates principles of quantum mechanics, particularly the](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F0aaf72ae-8073-4cb4-ae75-7d87fdc3f506%2F4c837bd3-c727-4ef0-9180-0d69523ae65f%2F2nttqv9_processed.jpeg&w=3840&q=75)
Transcribed Image Text:**Quantum Mechanics Problem: Tunneling Probability Across a Potential Barrier**
1. **Problem Description:**
- **System Setup:** Consider a system consisting of two conducting wires separated by a small distance \( L \). An electron has the potential to tunnel across this separation, also known as the air gap, by overcoming a potential difference.
- **Given Conditions:**
- The potential difference between the wires is denoted by \( U_0 - E = 0.25 \) eV.
- The probability of an electron successfully tunneling across this potential barrier is 0.02%.
- **Questions to Address:**
- What is the length of the gap, \( L \)?
- If the potential difference is increased to 0.75 eV, by how much must the gap be reduced to maintain the same tunneling probability?
**Conceptual Framework:**
- **Quantum Tunneling:** This phenomenon allows particles, such as electrons, to pass through a potential barrier that would be insurmountable according to classical physics. The probability \( P \) of tunneling is closely related to the height and width of the barrier.
- **Probability Calculation:**
- The tunneling probability \( P \) is often expressed in terms of the barrier properties and can be represented as:
\[
P \propto e^{-2 \kappa L}
\]
where \( \kappa \) is the decay constant given by:
\[
\kappa = \sqrt{\frac{2m(U_0 - E)}{\hbar^2}}
\]
Here, \( m \) is the mass of the electron and \( \hbar \) is the reduced Planck's constant.
- **Adjusting the Barrier:**
- If the potential difference changes, the decay constant \( \kappa \) and the required gap \( L \) must be adjusted accordingly to keep the tunneling probability constant.
**Graph and Diagram Explanation:**
- No graphs or diagrams are available in the provided text. However, if a graph were included, it might illustrate the relationship between the potential barrier height (\( U_0 - E \)), the gap distance (\( L \)), and the tunneling probability (\( P \)). A typical representation might show an exponential decay of tunneling probability with increasing barrier width and height.
This problem effectively integrates principles of quantum mechanics, particularly the
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