Question 1

Two lasers emit equal numbers of photons per second. If the first laser emits red light and the second emits blue light, the power radiated by the first is

Accepted Answer

The energy of a photon is given by $E = hf$, where $h$ is Planck's constant and $f$ is the frequency of the light. Blue light has a higher frequency than red light, so each photon of blue light carries more energy than a photon of red light. If both lasers emit the same number of photons per second, the laser emitting blue light will radiate more power because its photons each carry more energy.

Question 2

Silver has a work function of 4.73 eV. Photons of the threshold frequency would be described as which of the following?

Accepted Answer

The threshold frequency is the minimum frequency of a photon required to overcome the work function and cause photoemission. The formula is given as:
threshold frequency = work function / Planck's constant
Using the given work function of 4.73 eV and Planck's constant, we can calculate the threshold frequency as:
threshold frequency = (4.73 eV) / (4.136 x 10^-15 eV s) = 1.144 x 10^15 Hz
This frequency corresponds to the ultraviolet region of the electromagnetic spectrum. Therefore, photons of the threshold frequency would be described as ultraviolet.

Question 3

A quantized item

Accepted Answer

A quantized item has possible values that are limited to a discrete set, meaning it can only take on certain specific values rather than a continuous range.

Question 4

Using the quantum theory of EM waves, which scientist was successful in explaining the photoelectric effect (and later won a Nobel Prize for the work)?

Accepted Answer

Albert Einstein was successful in explaining the photoelectric effect using the quantum theory of EM waves, which he published in a 1905 paper that earned him the Nobel Prize in Physics in 1921.

Question 5

The energy of a photon of wavelength 400 nm is

Accepted Answer

The answer of The energy of a photon of wavelength...

Question 6

The work function of a surface is 6.53 × 10^-19 J. What is this quantity in eV?

Accepted Answer

The answer of The work function of a surface is...

Question 7

Sodium has a work function of 2.36 eV. Of the following choices, which is the one of the longest wavelength that could cause photoelectrons to be ejected from the sodium?

Accepted Answer

The answer of Sodium has a work function of 2.36...

Question 8

Photons from a source each have energy 3.30 eV. Photons from a second source have twice the frequency as those from the first source. What is the energy of a photon from the second source?

Accepted Answer

The energy of a photon is directly proportional to its frequency. If the second source has photons with twice the frequency of the first source, then the energy of these photons will also be twice that of the first source. Therefore, the energy of a photon from the second source is 2 * 3.30 eV = 6.60 eV.

Question 9

Which scientist proposed quantization of energy to overcome a major problem with understanding blackbody radiation?

Accepted Answer

Max Planck proposed quantization of energy in order to explain the phenomenon of blackbody radiation, which had been a major problem in physics at the time. His theory stated that energy is not continuous, but instead is made up of individual quanta. This idea later became one of the foundational concepts of quantum mechanics.

Question 10

A laser beam emits 2.5 × 10²⁰ photons per second with a wavelength of 663 nm. What is the power output of this laser?

Accepted Answer

The answer of A laser beam emits 2.5 × 10²⁰...

Question 11

What is the threshold frequency for a surface with work function 4.14 eV?

Accepted Answer

The threshold frequency (f₀) is calculated using the formula f₀ = φ/h, where φ is the work function (4.14 eV) and h is Planck's constant (4.14 × 10⁻¹⁵ eV·s). This gives f₀ ≈ 1.00 × 10¹⁵ Hz.

Question 12

A 1.00 mW laser produces photons of wavelength 633 nm. How many photons per second does the laser emit?

Accepted Answer

The energy of a single photon can be calculated using E = hc/λ, where h is Planck's constant (6.626 × 10^-34 J·s), c is the speed of light (3.00 × 10^8 m/s), and λ is the wavelength (633 nm = 633 × 10^-9 m). The power of the laser is 1.00 mW = 1.00 × 10^-3 J/s. The number of photons per second is the power divided by the energy per photon. This calculation results in approximately 3.19 × 10^15 photons per second.

Question 13

In a photoelectric effect experiment, the frequency of photons bombarding the surface is increased until photoelectrons just start to leave the surface. If this occurs at a frequency of 6.0 × 10¹⁴ Hz, what is the work function of the surface?

Accepted Answer

The work function ($\phi$) can be calculated using the equation $\phi = hf$, where $h$ is Planck's constant ($6.626 \times 10^{-34}$ J·s) and $f$ is the frequency of the incident light. Given $f = 6.0 \times 10^{14}$ Hz, $\phi = 6.626 \times 10^{-34} \text{ J·s} \times 6.0 \times 10^{14} \text{ Hz} = 3.976 \times 10^{-19}$ J. Converting joules to electronvolts (1 eV = $1.602 \times 10^{-19}$ J), $\phi \approx 2.48$ eV, which rounds to 2.5 eV, option D.

Question 14

Photons of red light cause a surface to emit photoelectrons with maximum kinetic energy K(red). If photons of blue light of the same intensity are now used in the experiment, which of the following statements is true about the photoelectrons emitted (if any are emitted)?

Accepted Answer

Blue light has a shorter wavelength (and thus higher energy) than red light. According to the photoelectric effect, the kinetic energy of photoelectrons is determined by the energy of the incident photons. Since blue light photons have more energy than red light photons, the maximum kinetic energy of photoelectrons emitted by blue light (K(blue)) will be greater than that emitted by red light (K(red)).

Question 15

Light of wavelength 400 nm bombards a surface that has a work function of 2.46 eV. What is the maximum kinetic energy of the photoelectrons from this surface?

Accepted Answer

The maximum kinetic energy of the photoelectrons can be calculated using the photoelectric equation: $KE_{max} = hf - \phi$, where $KE_{max}$ is the maximum kinetic energy of the photoelectrons, $h$ is Planck's constant ($6.626 \times 10^{-34} \, \text{m}^2 \, \text{kg} / \text{s}$), $f$ is the frequency of the incident light, and $\phi$ is the work function of the material. The frequency $f$ can be found from the wavelength $\lambda$ using the relation $f = \frac{c}{\lambda}$, where $c$ is the speed of light ($3.00 \times 10^8 \, \text{m/s}$). Given $\lambda = 400 \, \text{nm} = 400 \times 10^{-9} \, \text{m}$, and $\phi = 2.46 \, \text{eV}$, we first convert the work function to joules ($1 \, \text{eV} = 1.602 \times 10^{-19} \, \text{J}$), then calculate $KE_{max}$.First, convert the wavelength to frequency:$$f = \frac{c}{\lambda} = \frac{3.00 \times 10^8 \, \text{m/s}}{400 \times 10^{-9} \, \text{m}} = 7.5 \times 10^{14} \, \text{Hz}$$Then, calculate the energy of the photons using $E = hf$:$$E = (6.626 \times 10^{-34} \, \text{J s})(7.5 \times 10^{14} \, \text{Hz}) = 4.9695 \times 10^{-19} \, \text{J}$$Convert the work function to joules:$$\phi = 2.46 \, \text{eV} \times 1.602 \times 10^{-19} \, \text{J/eV} = 3.94092 \times 10^{-19} \, \text{J}$$Finally, calculate $KE_{max}$:$$KE_{max} = E - \phi = 4.9695 \times 10^{-19} \, \text{J} - 3.94092 \times 10^{-19} \, \text{J} = 1.02858 \times 10^{-19} \, \text{J}$$To convert $KE_{max}$ to electronvolts:$$KE_{max} = \frac{1.02858 \times 10^{-19} \, \text{J}}{1.602 \times 10^{-19} \, \text{J/eV}} \approx 0.640 \, \text{eV}$$

Question 16

A photon of frequency 6.40 × 10¹⁴ Hz has what energy?

Accepted Answer

The energy of a photon is given by the formula E = hf, where h is the Planck's constant (6.626 × 10^-34 J·s) and f is the frequency of the photon in Hz. 
So, E = (6.626 × 10^-34 J·s) × (6.40 × 10^14 Hz) = 4.23 × 10^-19 J 
To convert this energy into eV, we use the conversion factor: 1 eV = 1.60 × 10^-19 J 
So, E = (4.23 × 10^-19 J) / (1.60 × 10^-19 J/eV) = 2.65 eV 
Therefore, the answer is D: 2.65 eV

Question 17

A problem with the classical theory for radiation from a blackbody was that the theory predicted too much radiation in what range of wavelengths?

Accepted Answer

The classical theory for radiation from a blackbody, known as the Rayleigh-Jeans law, predicted too much radiation at short wavelengths, leading to the "ultraviolet catastrophe." This discrepancy was resolved by Max Planck's introduction of quantized energy levels, giving birth to quantum mechanics.

Question 18

A 2.00 eV photon has what frequency?

Accepted Answer

The answer of A 2.00 eV photon has what frequency?
...

Question 19

In Compton scattering, a photon of wavelength λ and frequency f is scattered from an electron, initially at rest. In this process,

Accepted Answer

In Compton scattering, the photon loses energy to the electron, causing a shift in the wavelength of the scattered photon. This shift results in the scattered photon having a lower frequency and longer wavelength than the original photon. Therefore, choice D is the best option.

Question 20

An x-ray photon of energy 3.20 × 10^-15 J has what wavelength?

Accepted Answer

We can use the equation E=hc/lambda, where E is the energy of the photon, h is Planck's constant, c is the speed of light, and lambda is the wavelength of the photon. Rearranging this equation, we get lambda = hc/E. Plugging in the given values, we get lambda = (6.626 x 10^-34 J s) x (3.00 x 10^8 m/s) / (3.20 x 10^-15 J) = 6.21 x 10^-11 m = 62.1 pm (picometers). Therefore, the best choice is B, with a wavelength of 62.1 picometers.

Quiz 27: Early Quantum Physics and the Photon

Two lasers emit equal numbers of photons per second. If the first laser emits red light and the second emits blue light, the power radiated by the first is

Silver has a work function of 4.73 eV. Photons of the threshold frequency would be described as which of the following?

A quantized item

Using the quantum theory of EM waves, which scientist was successful in explaining the photoelectric effect (and later won a Nobel Prize for the work) ?

The energy of a photon of wavelength 400 nm is

The work function of a surface is 6.53 × 10^-19 J. What is this quantity in eV?

Sodium has a work function of 2.36 eV. Of the following choices, which is the one of the longest wavelength that could cause photoelectrons to be ejected from the sodium?

Photons from a source each have energy 3.30 eV. Photons from a second source have twice the frequency as those from the first source. What is the energy of a photon from the second source?

Which scientist proposed quantization of energy to overcome a major problem with understanding blackbody radiation?

A laser beam emits 2.5 × 10²⁰ photons per second with a wavelength of 663 nm. What is the power output of this laser?

What is the threshold frequency for a surface with work function 4.14 eV?

A 1.00 mW laser produces photons of wavelength 633 nm. How many photons per second does the laser emit?

In a photoelectric effect experiment, the frequency of photons bombarding the surface is increased until photoelectrons just start to leave the surface. If this occurs at a frequency of 6.0 × 10¹⁴ Hz, what is the work function of the surface?

Photons of red light cause a surface to emit photoelectrons with maximum kinetic energy K(red) . If photons of blue light of the same intensity are now used in the experiment, which of the following statements is true about the photoelectrons emitted (if any are emitted) ?

Light of wavelength 400 nm bombards a surface that has a work function of 2.46 eV. What is the maximum kinetic energy of the photoelectrons from this surface?

A photon of frequency 6.40 × 10¹⁴ Hz has what energy?

A problem with the classical theory for radiation from a blackbody was that the theory predicted too much radiation in what range of wavelengths?

A 2.00 eV photon has what frequency?

In Compton scattering, a photon of wavelength λ and frequency f is scattered from an electron, initially at rest. In this process,

An x-ray photon of energy 3.20 × 10^-15 J has what wavelength?

Quiz 27: Early Quantum Physics and the Photon

Two lasers emit equal numbers of photons per second. If the first laser emits red light and the second emits blue light, the power radiated by the first is

Silver has a work function of 4.73 eV. Photons of the threshold frequency would be described as which of the following?

A quantized item

Using the quantum theory of EM waves, which scientist was successful in explaining the photoelectric effect (and later won a Nobel Prize for the work) ?

The energy of a photon of wavelength 400 nm is

The work function of a surface is 6.53 × 10-19 J. What is this quantity in eV?

Sodium has a work function of 2.36 eV. Of the following choices, which is the one of the longest wavelength that could cause photoelectrons to be ejected from the sodium?

Photons from a source each have energy 3.30 eV. Photons from a second source have twice the frequency as those from the first source. What is the energy of a photon from the second source?

Which scientist proposed quantization of energy to overcome a major problem with understanding blackbody radiation?

A laser beam emits 2.5 × 1020 photons per second with a wavelength of 663 nm. What is the power output of this laser?

What is the threshold frequency for a surface with work function 4.14 eV?

A 1.00 mW laser produces photons of wavelength 633 nm. How many photons per second does the laser emit?

In a photoelectric effect experiment, the frequency of photons bombarding the surface is increased until photoelectrons just start to leave the surface. If this occurs at a frequency of 6.0 × 1014 Hz, what is the work function of the surface?

Photons of red light cause a surface to emit photoelectrons with maximum kinetic energy K(red) . If photons of blue light of the same intensity are now used in the experiment, which of the following statements is true about the photoelectrons emitted (if any are emitted) ?

Light of wavelength 400 nm bombards a surface that has a work function of 2.46 eV. What is the maximum kinetic energy of the photoelectrons from this surface?

A photon of frequency 6.40 × 1014 Hz has what energy?

A problem with the classical theory for radiation from a blackbody was that the theory predicted too much radiation in what range of wavelengths?

A 2.00 eV photon has what frequency?

In Compton scattering, a photon of wavelength λ and frequency f is scattered from an electron, initially at rest. In this process,

An x-ray photon of energy 3.20 × 10-15 J has what wavelength?

The work function of a surface is 6.53 × 10^-19 J. What is this quantity in eV?

A laser beam emits 2.5 × 10²⁰ photons per second with a wavelength of 663 nm. What is the power output of this laser?

In a photoelectric effect experiment, the frequency of photons bombarding the surface is increased until photoelectrons just start to leave the surface. If this occurs at a frequency of 6.0 × 10¹⁴ Hz, what is the work function of the surface?

A photon of frequency 6.40 × 10¹⁴ Hz has what energy?

An x-ray photon of energy 3.20 × 10^-15 J has what wavelength?