Physics 121: Quiz 1-4 Questions
What statement is not a statement that is in agreement with one (or more) of Newtons 3 Laws of motion?
An object can move in a circle even if there are no forces acting on it
Quantum wavefunctions add together according to the principle of superposition, which is a fancy way of saying what?
Different outcomes can happen, but different add-ins can interfere with each other.
A surprising discovery in quantum mechanics, is the ability to measure something without directly measuring it (or more precisely without interacting with it). By carefully engineering a generalization of the observed double slit one can determine whether an object is present. What about this process is true?
It always has a chance of failure, but it can work arbitrarily often.
A surprising discovery in quantum mechanics, is the ability to measure something without measuring it (or more precisely without interacting with it). By carefully engineering a generalization of the observed double slit one can determine whether an object is present. What about this process is true?
It always has a chance of failure, but it can work arbitrarily often.
What statement about Isaac Newton's model of light is true?
It is a stream of particles that obey Newton's Three Laws of Motion
(What statement best describes the "theory of quantum mechanics" ? (think properties)
It is non-local, non-deterministic and counter-factual indefinite
When we make a measurement of a system, we don't measure the wavefunction, rather we measure a particular property (e.g. the electron is located here, the photon is vertically polarized, etc.). When performing a measurement what happens to the wavefunction?
It localizes around the value that was measured, called projection or collapse
What statement describes aspects of Christiaan Huygens' wave theory of light?
Light is waves in a substance called the "ether," and this can explain the phenomena of reflection, refraction and shadow formation
Which of the following most accurately describes our current understanding of the nature of light?
Light sometimes behaves as a wave and sometimes as tiny particles that move at the speed of light
What statement accurately describes why large objects, such as baseballs, do not apparently display any of the "unusual" behaviors associated with Quantum Mechanics, and instead obey the laws of Classical Physics?
Objects like baseballs are comprised of an enormous number of atoms that are constantly interacting with each other, and the environment, and this ultimately makes the unusual outcomes very unlikely
Light is a wave in the electromagnetic fields, and as a wave it has an orientation to how it waves (does the electric field wave up and down or left to right). While there is a lot of fascinating classical phenomenology related to this (like how to make anti-glare windscreens), its quantum mechanical realization is perhaps its most intriguing. Light polarizations can be constructed as a superposition of the two basic polarizations (vertical and horizontal), and we see this explicitly in the following:
Place three polarization filters one behind the next rotated 45° relative to each other, and 25% of the light gets through.
Which of the following phenomena is an example of diffraction of light?
Poisson's spot (shadow of pinhead)
Which of the following best represents a key principle of the Copenhagen interpretation, which explains the nature of reality in the quantum world? (distinguishing it from other "interpretations")
Quantum particles simultaneously exist in both wave and particle forms.
The Quantum Zeno Effect (named for the paradoxes of Zeno) is a surprising result in quantum measurement. In essence it says:
Sufficiently rapid measurements can halt a system's evolution.
Which of the following describes an aspect of Heisenberg's Uncertainty Principle?
The more precisely you measure the position of an electron, the less precise your knowledge of its velocity
In quantum mechanics, rather than describing the evolution of observable properties of a system, we describe the evolution of the Wavefunction. Thanks to Max Born, we now have an interpretation of the wavefunction as:
The probability amplitude of the system to be in a given state.
An electron is shot from an "electron gun" (a device that can shoot electrons, much like a gun shots bullets). What quantities can be precisely predicted, according to the laws of Quantum Mechanics? a.
The probability that an electron will be in any given location one second after it has been shot from the gun
What is the central mystery of quantum mechanics as discussed in Chapter 8 of In search of Schrodinger's Cat?
The quantum world consists of "ghost realities" that become real upon observation
A single atom is placed inside a "box" that is kept at absolute vacuum (so nothing inside the box except the atom). When placing the atom in the box, it is observed to be at rest (not moving at all) when the box is closed. What statement is the most accurate description of the state of the atom, after the box has been closed, according to the theory of Quantum Mechanics?
Where the atom is, within the box, and what its state of motion is (at rest, moving, etc.) are both undefined
Which of the following phenomena, regarding the behavior of light is, noteasily explained by Newton, using his theory of the nature of light?
diffraction of light
Which of the following statements most accurately describes a situation of total destructive wave interference?
the crest of one wave overlaps with the trough of a second wave
Which of the following statements is not an accurate description of the double-slit interference pattern?
the pattern can be explained by theorizing that light consists of a beam of tiny particles
Which of the following is not a correct mathematical formula describing properties of waves? N. B. 𝜆=λ= wavelength, 𝑓=f= frequency, 𝑣=v= velocity, 𝑇=T= period, 𝐴=A= amplitude, 𝐸=E= energy.
𝐴=1/𝐸A=1/E
