Question 1

Quantum uncertainties are most predominant for simultaneously measuring the speed and location of
A) a spitball.
B) a baseball.
C) an electron.

Accepted Answer

Quantum uncertainties, as described by Heisenberg's uncertainty principle, are most significant at the quantum scale, affecting particles like electrons. This principle states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa. This effect is negligible for macroscopic objects like spitballs and baseballs, but it is fundamental for microscopic particles such as electrons.

Question 2

An atom that absorbs a photon of a certain energy can then emit
A) only a photon of the same or higher energy.
B) a photon of any energy.
C) only a photon of that energy.
D) only a photon of the same or lower energy.

Accepted Answer

When an atom absorbs a photon, it can emit a photon of the same or lower energy. The energy difference (if lower) corresponds to the energy lost to other processes, such as heat or non-radiative transitions.

Question 3

If atoms were smaller, Planck's constant would be
A) larger.
B) smaller.
C) no different in physical size.

Accepted Answer

Planck's constant is a fundamental physical constant that is not dependent on the size of atoms. It is a property of the quantum mechanical world and remains constant regardless of the physical size of atoms. However, if atoms were smaller, implying a change in the scale of physical phenomena, it could conceptually affect the numerical values of physical constants when expressed in units that are derived from atomic properties. But fundamentally, Planck's constant itself, as a measure of the quantization of action in the universe, would not change. The choice B is incorrect based on a misunderstanding of the question's intent and the nature of physical constants.

Question 4

Orbital electrons do not spiral into the nucleus because of
A) electromagnetic forces.
B) angular momentum conservation.
C) the wave nature of the electron.
D) the large nuclear size compared to the electron's size.
E) none of these

Accepted Answer

The wave nature of the electron, as described by quantum mechanics, prevents electrons from spiraling into the nucleus. Electrons exist in stable orbitals due to their wave-like properties, which create standing wave patterns that do not allow them to lose energy and spiral inward.

Question 5

Which has less energy per photon?
A) blue light
B) red light
C) Both have the same energy.

Accepted Answer

Red light has less energy per photon compared to blue light. This is because the energy of a photon is directly proportional to its frequency (E = hf), and inversely proportional to its wavelength. Red light has a longer wavelength and lower frequency than blue light, thus it has less energy per photon.

Question 6

The ratio of a photon's energy to its frequency is
A) its speed.
B) its wavelength.
C) Planck's constant.
D) its amplitude.
E) none of these

Accepted Answer

The ratio of a photon's energy (E) to its frequency (f) is given by E = hf, where h is Planck's constant. This relationship is a fundamental principle of quantum mechanics.

Question 7

An excited hydrogen atom is capable of emitting radiation of
A) a single frequency.
B) 3 frequencies.
C) many more than 3 frequencies.

Accepted Answer

An excited hydrogen atom can emit radiation of many more than 3 frequencies because the energy level transitions of the electron can result in a wide range of energy differences and therefore a wide range of frequencies when radiation is emitted as the electron returns to its ground state.

Question 8

The highest frequency light of those below is
A) red.
B) blue.
C) green.
D) violet.
E) all the same

Accepted Answer

Violet light has the highest frequency among the options given. In the visible spectrum, violet light has shorter wavelengths and thus higher frequencies compared to red, blue, and green light.

Question 9

A lump of energy associated with light is called a
A) photon.
B) quantum.
C) both of these
D) neither of these

Accepted Answer

A lump of energy associated with light can be referred to as both a photon and a quantum, as these terms are used in physics to describe the smallest quantity of energy that can be transported or interact in light and other forms of electromagnetic radiation.

Question 10

Isolated bells ring clear, while bells crammed in a box have a muffled ring. If the sound of isolated bells is analogous to light from a gas discharge tube, then sound from the box crammed with bells
Is analogous to light from
A) a fluorescent lamp.
B) an incandescent lamp.
C) a laser.
D) a phosphorescent source.
E) none of these

Accepted Answer

The sound from the box crammed with bells is analogous to light from an incandescent lamp because both produce a broad range of frequencies/wavelengths due to the interactions and overlapping of waves, unlike the discrete frequencies produced by isolated bells or a gas discharge tube.

Question 11

We now consider the Bohr model of the atom to be
A) totally useless - of historical interest only.
B) defective and oversimplified, but still useful.
C) an accurate picture of a hydrogen atom.

Accepted Answer

The Bohr model, while not accurate for describing complex atoms or incorporating quantum mechanics fully, still provides a useful framework for understanding basic atomic structure and energy levels, especially for the hydrogen atom. It introduces the concept of quantized energy levels, which is a fundamental principle in quantum mechanics.

Question 12

The greater proportion of energy immediately converted to heat rather than light occurs in
A) a fluorescent lamp.
B) an incandescent lamp.
C) both the same

Accepted Answer

In an incandescent lamp, the majority of the electrical energy is converted into heat, and only a small portion is converted into visible light. This is because the filament inside the bulb becomes extremely hot and emits light as a result of thermal radiation. In comparison, a fluorescent lamp uses a different mechanism to produce light, where electricity excites mercury vapor to emit UV light, which is then converted into visible light by a phosphorescent coating on the inside of the lamp. As a result, less energy is lost as heat in a fluorescent lamp, making it more energy-efficient than an incandescent lamp.

Question 13

The white light emitted by a fluorescent lamp is provided by the
A) filtering effect of the glass tubing.
B) phosphors on the inner surface of the lamp.
C) high temperature of the glowing gas.
D) mercury vapor in the lamp.

Accepted Answer

The white light in a fluorescent lamp is produced by phosphors that coat the inner surface of the tube. These phosphors fluoresce (emit light) when they are excited by ultraviolet light produced by the mercury vapor in the lamp, converting the UV light into visible light.

Question 14

Compared to the wavelengths of visible light, the wavelengths of matter waves are relatively
A) large.
B) small.

Accepted Answer

Matter waves have much smaller wavelengths compared to visible light. This is because the de Broglie wavelength (wavelength of matter wave) is inversely proportional to the mass of the object, which is much larger for visible light (photons) than for macroscopic objects such as electrons, protons or even atoms. Therefore, matter waves have much smaller wavelengths than visible light.

Question 15

The main reason electrons occupy discrete orbits in an atom is because
A) electric forces act over quantized distances.
B) energy levels are quantized.
C) electrons are basically discrete particles.
D) the circumference of each orbit is an integral multiple of electron wavelengths.
E) none of these

Accepted Answer

The answer of The main reason electrons occupy discrete orbits...

Question 16

The fact that iron absorption lines occur in the solar spectrum directly indicates that there is iron in the solar
A) interior.
B) atmosphere.
C) surface.

Accepted Answer

The presence of iron absorption lines in the solar spectrum indicates that light from the Sun is passing through iron atoms in the solar atmosphere, which absorb specific wavelengths of light, thus revealing the presence of iron in the solar atmosphere.

Question 17

According to quantum physics, looking at a star through a telescope
A) affects the processes occurring in the star.
B) has no effect on the processes occurring in the star.

Accepted Answer

According to the principles of quantum physics, the act of observation itself can affect the behavior of particles on a quantum level. However, this does not apply to macroscopic objects like stars, which are not subject to the same rules as subatomic particles. Therefore, looking at a star through a telescope has no effect on the processes occurring in the star.

Question 18

The dark lines in the sun's spectrum represent light that is
A) emitted by the sun.
B) absorbed by the sun's atmosphere.
C) not emitted by the sun.

Accepted Answer

The dark lines in the sun's spectrum, known as absorption lines, represent light that is absorbed by elements in the sun's atmosphere. When light from the sun passes through its atmosphere, atoms and molecules absorb specific wavelengths of light, creating these dark lines in the spectrum.

Question 19

In the photoelectric effect, the greater the frequency of the illuminating light, the greater the
A) number of ejected electrons.
B) maximum velocity of ejected electrons.
C) both of these
D) neither of these

Accepted Answer

The photoelectric effect demonstrates that the maximum kinetic energy (and thus velocity) of ejected electrons increases with the frequency of the illuminating light, not the number of ejected electrons, which is related to the intensity of the light.

Question 20

In the process of fluorescence, part of the input energy immediately
A) is emitted as higher-frequency light and the rest lower- frequency light.
B) becomes internal energy and the rest lower-frequency light.
C) cascades to excite other atoms in the material.
D) excites electrons to metastable states.
E) none of these

Accepted Answer

In fluorescence, part of the input energy is converted into internal energy (heat, vibrations, etc.), and the rest is emitted as light of a lower frequency than the absorbed light. This is because the emitted photons have less energy than the absorbed ones, with the difference typically dissipated as heat within the material.

Quiz 15: Quantum Theory

Quantum uncertainties are most predominant for simultaneously measuring the speed and location of

An atom that absorbs a photon of a certain energy can then emit

If atoms were smaller, Planck's constant would be

Orbital electrons do not spiral into the nucleus because of

Which has less energy per photon?

The ratio of a photon's energy to its frequency is

An excited hydrogen atom is capable of emitting radiation of

The highest frequency light of those below is

A lump of energy associated with light is called a

Isolated bells ring clear, while bells crammed in a box have a muffled ring. If the sound of isolated bells is analogous to light from a gas discharge tube, then sound from the box crammed with bells Is analogous to light from

We now consider the Bohr model of the atom to be

The greater proportion of energy immediately converted to heat rather than light occurs in

The white light emitted by a fluorescent lamp is provided by the

Compared to the wavelengths of visible light, the wavelengths of matter waves are relatively

The main reason electrons occupy discrete orbits in an atom is because

The fact that iron absorption lines occur in the solar spectrum directly indicates that there is iron in the solar

According to quantum physics, looking at a star through a telescope

The dark lines in the sun's spectrum represent light that is

In the photoelectric effect, the greater the frequency of the illuminating light, the greater the

In the process of fluorescence, part of the input energy immediately