What Limits Observation in Quantum Mechanics?

In summary, the longest-wavelength photon that can be observed for an object of size 0.5 Angstrom is 0.5 Angstrom. To find this, we use the equation E=hf to calculate the energy of the photon. For the smallest-energy electron that can be used to make the measurement, we need to calculate its momentum, which we can find from the momentum of the photon in problem 1. Then, we can use this momentum to find the energy of the electron and use equation 2 to calculate the minimum energy needed for the measurement.
  • #1
blade_090
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1. Homework Statement [/b]
1)for an object of size 0.5 Angstrom, what is the longest-wavelength photon with which it can be observed?
2)for the object of problem 1, what is the smallest-energy electron which can be used to make the measurement?

Homework Equations


1)[tex]\Delta[/tex]p x [tex]\Delta[/tex] x [tex]\geq[/tex] [tex] h\ =\ 6.62606876(52)\ \times\ 10^{-34}\ J\ s[/tex]/4(3.142)

2)[tex]\Delta[/tex]E x [tex]\Delta[/tex] t [tex]\geq[/tex] [tex] h\ =\ 6.62606876(52)\ \times\ 10^{-34}\ J\ s[/tex]/4(3.142)

for problem 1,
0.5Angstrom is the wavelength.
i use the equation of E=hf to find the energy.
thn i use 2nd equation above to find [tex]\Delta[/tex] t
i use the [tex]\Delta[/tex] t [tex]\geq[/tex] [(lamda)^2]/4(pi)(speed of light)(delta lamda)
i did find the answer...bt somehow i feel like i did wrong

for problem 2,
i duno where i should start...
i tinking of using equation 2 bt I am not sure...whether energy equation from above is correct

the answer for prob 1 : 0.5Angstrom
the answer for prob 2 : 602eV
 
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  • #2
blade_090 said:
1. Homework Statement [/b]
1)for an object of size 0.5 Angstrom, what is the longest-wavelength photon with which it can be observed?
2)for the object of problem 1, what is the smallest-energy electron which can be used to make the measurement?

Homework Equations


1)[tex]\Delta[/tex]p x [tex]\Delta[/tex] x [tex]\geq[/tex] [tex] h\ =\ 6.62606876(52)\ \times\ 10^{-34}\ J\ s[/tex]/4(3.142)

2)[tex]\Delta[/tex]E x [tex]\Delta[/tex] t [tex]\geq[/tex] [tex] h\ =\ 6.62606876(52)\ \times\ 10^{-34}\ J\ s[/tex]/4(3.142)
for problem 1,
0.5Angstrom is the wavelength.
i use the equation of E=hf to find the energy.

No, 0.5A is the size of the object. You're supposed to find the wavelength of the photon. If you were trying to find the de Broglie wavelength of the object, you can't use E=hf because that only applies to photons.

Can you find the momentum of the photon? If so, what's the relationship between a photon's momentum and its wavelength?

for problem 2,
i duno where i should start...
i tinking of using equation 2 bt I am not sure...whether energy equation from above is correct

Once you find the momentum from problem 1, you can apply it to an electron. How do you find an electron's energy from its momentum?
 

FAQ: What Limits Observation in Quantum Mechanics?

What is the Uncertainty Principle?

The Uncertainty Principle is a fundamental concept in quantum mechanics that states that certain pairs of physical properties of a particle, such as position and momentum, cannot both be known simultaneously with perfect accuracy.

Who discovered the Uncertainty Principle?

The Uncertainty Principle was first proposed by German physicist Werner Heisenberg in 1927.

How does the Uncertainty Principle affect our understanding of the physical world?

The Uncertainty Principle challenges the classical Newtonian view of the world, where objects have predetermined positions and velocities. It shows that at the quantum level, properties such as position and momentum are inherently uncertain and can only be described in terms of probabilities.

Is the Uncertainty Principle proven?

Yes, the Uncertainty Principle has been extensively tested and verified through numerous experiments. It is considered one of the most well-established and experimentally supported principles in quantum mechanics.

What are the practical implications of the Uncertainty Principle?

The Uncertainty Principle has led to the development of technologies such as electron microscopes and MRI machines. It also plays a crucial role in fields such as quantum computing and cryptography, where the ability to manipulate and measure particles at the quantum level is essential.

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