physics midterm

Which of the following phenomena is an example of diffraction of light? a. Poisson's spot (shadow of pinhead) b. Refraction of light as it passes from one substance to another c. speed of light being different for propagation through different substances d. Distortion of images of objects that are underwater e. the finite speed of light

a. Poisson's spot (shadow of pinhead)

Which of the following statements most accurately describes a situation of total destructive wave interference? a. the node of one wave overlaps with the trough of a second wave b. the trough of one wave overlaps with the trough of a second wave c. the crest of one wave overlaps with the trough of a second wave d. the node of one wave overlaps with the crest of a second wave e. the crest of one wave overlaps with the crest of a second wave

c. the crest of one wave overlaps with the trough of a second wave

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? a. It localizes around the value that was measured, called projection or collapse. b. It remains unchanged, and if we measure again we might not get a similar answer. c. It spreads out, becoming uncertain. d. It goes away, leaving a classical particle.

a. It localizes around the value that was measured, called projection or collapse.

Which of the following most accurately describes our current understanding of the nature of light? a. Light sometimes behaves as a wave and sometimes as tiny particles that move at the speed of light b. Light is composed of tiny particles that move at the speed of light c. Light is a fluid of some type d. Light is as a wave of some type e. Visible light is a wave, but light that we cannot see is composed of particles

a. Light sometimes behaves as a wave and sometimes as tiny particles that move at the speed of light

Which of the following statements most 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? a. 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 b. The laws of Quantum Mechanics are only valid for small things like atoms, and not everyday objects c. It is still unknown as to why large, everyday objects such as baseballs follow the laws of Classical Mechanics, and not the laws of Quantum Mechanics d. Objects like baseballs are not made of the things that obey the laws of Quantum Mechanics

a. 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

The Quantum Zeno Effect (named for the paradoxes of Zeno) is a surprising result in quantum measurement. In essence it says: a. Sufficiently rapid measurements can halt a system's evolution. b. Sufficiently rapid measurements can force a system to change state. c. Measuring a system projects it into a definite state. d. An observed system will always be in the same state. e. A well isolated system will not evolve.

a. Sufficiently rapid measurements can halt a system's evolution.

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. 𝐴=1/𝐸A=1/E b. 𝜆𝑓=𝑣 c. 𝑓=1/𝑇 d. 𝐸 is proportional to the square of 𝐴 e. 𝜆=𝑣/𝑓

a. 𝐴=1/𝐸

Which of the following is not a statement that is in agreement with one (or more) of Newton's Three Laws of Motion? a. The net force acting on an object is always given by the product of the object's mass and the value of its acceleration b. An object can move in a circle even if there are no forces acting on it c. When two objects interact with each other, any forces they exert on each other are equal in size but in opposite directions d. The acceleration of an object is always given by the value of the net force acting on it divided by the object's mass e. The motion of an object that has zero net force acting on it is either: at rest (no motion); or in a straight line, with constant speed.

b. An object can move in a circle even if there are no forces acting on it

Which of the following statements about Isaac Newton's model of light is true? a. It is a wave phenomenon of some sort b. It is a stream of particles that obey Newton's Three Laws of Motion c. It is a model that explains the phenomena of shadows and reflection, but not of refraction d. It is pure energy, taking the form of neither a stream of particles nor a wave of some sort

b. It is a stream of particles that obey Newton's Three Laws of Motion

Which of the following statements is not an accurate description of the double-slit interference pattern? a. the pattern can be explained by theorizing that light is a wave phenomenon b. the pattern can be explained by theorizing that light consists of a beam of tiny particles c. the pattern consists of alternating bands of high (bright) and low (dark) light intensity at the observation screen d. the pattern arises due to the differences in the distance from each slit to points on the observation screen

b. the pattern can be explained by theorizing that light consists of a beam of tiny particles

Which of the following most accurately describes aspects of Christiaan Huygens' wave theory of light? a. Light is composed of a stream of particles that move in wave-like patterns b. Light is a wave, which describes some phenomena, such as reflection and refraction, but does not explain formation of shadows c. Light is waves in a substance called the "ether," and this can explain the phenomena of reflection, refraction and shadow formation d. Light is waves in air, being energized.

c. Light is waves in a substance called the "ether," and this can explain the phenomena of reflection, refraction and shadow formation

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: a. The system itself, which is generically spread out. b. The probability the system is in a given state. c. The probability amplitude of the system to be in a given state. d. As an unobservable wave that pushes the observable particles around.

c. The probability amplitude of the system to be in a given state.

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. Which of the following statements is the most accurate description of the state of the atom, after the box has been closed, according to the theory of Quantum Mechanics? a. The location of the atom is where it was placed before closing the box, but its state of motion is undefined (it may no longer be at rest) b. The atom is not where it was originally placed and is likely close to one of the walls of the box c. Where the atom is, within the box, and what its state of motion is (at rest, moving, etc.) are both undefined d. The location of the atom is unknown (it may no longer be in the location where it was placed), but we know that if we open the box it will snap back to where it was originally placed

c. Where the atom is, within the box, and what its state of motion is (at rest, moving, etc.) are both undefined

Quantum wavefunctions add together according to the principle of superposition, which is a fancy way of saying what? a. Different outcomes can happen independently of each other (i.e. different add-ins don't affect each other) b. Measuring the properties of a system can be done for each add-in separately, and the results can be averaged to get the full result. c. You can measure the position of a particle to be in multiple places at once. d. Different outcomes can happen, but different add-ins can interfere with each other.

d. 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 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? a. It's simply an application of a "Null" measurement. b. It works no better than 50% of the time. c. It's theoretically true, but hasn't been experimentally verified. d. It always has a chance of failure, but it can work arbitrarily often.

d. It always has a chance of failure, but it can work arbitrarily often.

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: a. Shine a single photon at three polarization filters, one behind the next, rotated 45° relative to each other, and the photon makes it through with 25% of its energy. b. Place two orthogonal polarization filters one behind the other, and no light gets through. c. Shine light through a birefringent material and its polarization will change. d. Place three polarization filters one behind the next rotated 45° relative to each other, and 25% of the light gets through.

d. 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 describes an aspect of Heisenberg's Uncertainty Principle? a. You can measure position and velocity of an electron, simultaneously, to as great precision as you wish b. The position of an electron is always unknown c. The more precisely you measure the position of an electron, the more precisely you know its velocity, as well d. The more precisely you measure the position of an electron, the less precise your knowledge of its velocity

d. The more precisely you measure the position of an electron, the less precise your knowledge of its velocity

An electron is shot from an "electron gun" (a device that can shoot electrons, much like a gun shots bullets). Which of the following quantities can be precisely predicted, according to the laws of Quantum Mechanics? a. The location and velocity and velocity of an electron one second after it has been shot from the gun b. The location, but not the velocity, of an electron one second after it has been shot from the gun c. Neither the location, nor velocity, nor probabilities of being in any given location or having any given velocity can be predicted d. The probability that an electron will be in any given location one second after it has been shot from the gun

d. The probability that an electron will be in any given location one second after it has been shot from the gun

Which of the following statements best describes the "theory of quantum mechanics" (properties that it incorporates)? a. It is local, non-deterministic and counter-factual indefinite b. It is non-local, non-deterministic and counter-factual definite c. It is non-local, deterministic and counter-factual indefinite d. It is local, non-deterministic and counter-factual definite e. It is non-local, non-deterministic and counter-factual indefinite

e. It is non-local, non-deterministic and counter-factual indefinite

The Quantum Zeno Effect (named for the paradoxes of Zeno) is a surprising result in quantum measurement. In essence it says: a. A well isolated system will not evolve. b. Sufficiently rapid measurements can force a system to change state. c. An observed system will always be in the same state. d. Measuring a system projects it into a definite state. e. Sufficiently rapid measurements can halt a system's evolution.

e. Sufficiently rapid measurements can halt a system's evolution.

Which of the following phenomena, regarding the behavior of light is, not easily explained by Newton, using his theory of the nature of light? a. refraction of light as it passes through one material into another b. energy stored in light c. finite travel speed of light d. reflection of light off of a surface of a material e. diffraction of light

e. diffraction of light