All GRE Subject Test: Physics Resources
Example Questions
Example Question #1 : Quantum Mechanics And Atomic Physics
Which of the following wavelengths could be used to measure the position of an electron with the greatest accuracy?
Red light
Gamma-rays
Radio
Infared
X-ray
Gamma-rays
The Heisenberg Uncertainty principle states that
Therefore, the smallest wavelength will have the lowest uncertainty in the position. Thus, we must pick the regime of options given which has the lowest wavelength. That is gamma-ray.
Example Question #2 : Quantum Mechanics And Atomic Physics
What wavelength will result in the most accurate measurement of the momentum of an electron?
Gamma-ray
Infrared
X-ray
Radio
Red light
Radio
The Heisenberg Uncertainty Principle states that:
Since the uncertainty in the position is inversely proportional to the uncertainty in the momentum, we need to pick the longest wavelength. Of the options listed, radio has the longest wavelength.
Example Question #3 : Quantum Mechanics And Atomic Physics
If a ground state particle is in a one-dimension square well, where is the probability of finding the particle equal to zero?
None of these
At the boundary.
the way in the box.
the way in the box.
In the middle.
At the boundary.
This is a fundamental concept question. For a ground state particle, the only place where the probability is equal to zero is at the boundary because the particle cannot be found there. He has to be in the box (not unlike a cat).
Example Question #4 : Quantum Mechanics And Atomic Physics
What is the energy of the photon emitted when a Hydrogen atom makes a transition from the to the atomic energy level?
, where refers to the final and initial energy levels, respectively.
However, since the question asked what is the energy of the photon, it is the absolute value of the energy calculated above because of conservation of energy. The photon carries away the energy lost by the atom.
Example Question #5 : Quantum Mechanics And Atomic Physics
What color will be emitted in the to transition in the Hydrogen Balmer series?
Yellow
Blue
Red
Violet
Green
Violet
.
Here, is the wavelength, is the Rydberg constant, for the Balmer series, and refers to the upper atomic level (this is in this case). Now, we just need to plug everything in, and solve for wavelength.
By inverting, This is in the violet regime of the visible spectrum.