Why can't we use negative values of n in the 1D particle in a box system?

In summary, the reason we do not take negative integer values of n in the 1D particle in a box system is because it would result in a negative wavelength, which contradicts the derivation where we get ka=n (wavelength). This condition is due to the wave function being zero at the boundary of the box. The quantized variable is related to the energy state, which is proportional to n^2 rather than n. The difference between ±n is only a complex phase factor and does not affect physically measurable quantities. Replacing a positive value of n with a negative value does not make a difference in the wave function or physically measurable quantities.
  • #1
Thejas15101998
43
1
In the 1D particle in a box system why don't we take negative integer values of n besides the positive integer values? Well I thought about it and I think the reason is that during derivation we get ka=n (wavelength ) and thus n being negative implies that wavelength is negative hence contradiction.
 
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  • #2
Thejas15101998 said:
I think the reason is that during derivation we get ka=n (wavelength ) and thus n being negative implies that wavelength is negative hence contradiction.

what is n?
Iis it related to k= n.pi/L or n.pi/a if a is the width of the box
moreover this condition is due to the acceptable wave function (solution of the Schrodinger equation) being zero at the boundary
i.e. at x=0 and x=a

and which dynamical variable is being quantised ?
Is it energy state ?
and if its energy ,then it may be proportional to n^2 rather than n.
 
  • #3
Quantum states are uniquely defined up to a complex phase factor. What difference is there between ±n?
 
  • #4
Thejas15101998 said:
In the 1D particle in a box system why don't we take negative integer values of n besides the positive integer values?
How does the wave function change for e.g. the second eigenstate if you replace n = +2 with n = -2? Does this make any difference in physically measurable quantities?
 
  • #5
Here we are considering the time independent Schrödinger equation.
 
  • #6
This may not make any difference in the physically measurable that is probability.
 

1. What is a "Particle in a 1D box" system?

A particle in a 1D box system is a simplified model used in quantum mechanics to study the behavior and properties of a particle confined in a one-dimensional space. The particle is assumed to have zero potential energy outside of the box and infinite potential energy within the box, creating a well-defined and bounded system.

2. How is the energy of a particle in a 1D box calculated?

The energy of a particle in a 1D box can be calculated using the Schrödinger equation, which is a fundamental equation in quantum mechanics. The energy levels are quantized, meaning they can only take on certain discrete values determined by the size of the box and the mass of the particle.

3. How does the size of the box affect the energy levels of the particle?

The size of the box directly affects the energy levels of the particle in a 1D box system. As the size of the box decreases, the energy levels become more closely spaced, and the energy of the particle increases. Conversely, as the size of the box increases, the energy levels become more widely spaced, and the energy of the particle decreases.

4. What is the significance of the particle in a 1D box system in quantum mechanics?

The particle in a 1D box system is a simple yet important model in quantum mechanics. It allows us to understand the behavior of a particle in a confined space and provides a foundation for more complex systems. It also demonstrates the concept of quantization in energy levels, which is a fundamental principle in quantum mechanics.

5. Can the particle in a 1D box system be applied to real-world scenarios?

While the particle in a 1D box system is a simplified model and cannot fully represent real-world systems, it can be applied to certain scenarios. For example, it can be used to study the behavior of electrons in a nanoscale semiconductor device or the vibrations of atoms in a solid material. However, it should be noted that the model has limitations and cannot fully capture all aspects of these real-world systems.

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