Questions and Answers
Energy is quantized. What does this mean?
Which of the following statements correctly describe the photoelectric effect? Select all that apply.
Which of the following statements correctly describe a photon? Select all that apply.
Which of the following correctly reflects the relationship between energy and frequency?
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In a photoelectric diode, no current will flow unless light of a certain minimum 'threshold' frequency is used. Which of the following explains this observation correctly?
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Energy is not continuous, but is quantized or divided into 'packets,' each of which contains a definite amount of energy. An energy packet is called a(n) _____, and the energy of each packet is directly proportional to its _____.
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In a photoelectric cell, an electric current is produced by shining a light on a metal plate. The minimum frequency required to cause a current to flow is called the ____ frequency.
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Calculate the energy of a photon of orange light with a wavelength of 600 nm.
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Electromagnetic radiation consists of particles called ____, which are characterized by a specific wavelength and _____.
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Which of the following statements correctly describe atomic line spectra? Select all that apply.
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Which of the following correctly expresses energy in terms of Planck's constant? Select all that apply.
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In order for a current to flow in a photoelectric cell, a photon of light must be ____ by an electron in the metal. For this to occur, the ____ of the photon must be equal to or greater than the energy needed to remove the electron from its energy state. It is the ____ of the light that is important, not its intensity.
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According to the Bohr model for the hydrogen atom, the energy of the atom is not continuous but has certain discrete energy _____, each of which is related to a fixed circular _____ of the electron around the nucleus. The farther the electron is from the nucleus, the _____ the energy of the system.
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The energy of a photon with a frequency of 1.0 x 10^15 s^-1 is equal to ______ J. h = 6.63 x 10^-34 J·s.
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An emission spectrum showing discrete, specific wavelengths is called a _____.
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Which of the following statements correctly describe the Bohr model of the hydrogen atom? Select all that apply.
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Atoms, like all other matter, have specific energy levels within them. For an atom to absorb radiation, the energy of the radiation must match the energy _____ between the two energy levels in the atoms.
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In Bohr's model of the atom, the quantum number n is associated with the _____ of an electron orbit. The lower the n value, the _____ the electron is to/from the nucleus and the _____ the energy level.
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Determine the wavelength of radiation emitted when the electron in a hydrogen atom moves from n = 4 to n = 1. In what region of the electromagnetic spectrum does this emission occur?
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Which of the following statements correctly describes how energy is absorbed by an atom?
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Which statement correctly describes the quantum number n with reference to the Bohr model of the hydrogen atom? Select all that apply.
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An electron in the n = 3 energy level of the hydrogen atom emits a photon with wavelength 656.27 nm. What is the change in energy of the electron, and to which energy level does it move?
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Study Notes
Quantization of Energy
- Energy is quantized, meaning it has a basic unit that cannot be subdivided further.
- The energy of photons can only be absorbed or emitted in fixed quantities.
Photoelectric Effect
- Electrons are ejected from metals when light of a specific frequency hits them, which is known as the threshold frequency.
- The kinetic energy of ejected electrons depends on the frequency of the incident light; greater frequency means higher kinetic energy.
- A light current begins to flow instantly when the appropriate frequency light strikes the metal surface.
Photons
- Photons are particles of electromagnetic radiation characterized by wavelength and frequency.
- Matter can only absorb or emit whole photons, not fractions of them.
Energy-Frequency Relationship
- The equation that represents the relationship between energy (E) and frequency (ν) in quantum mechanics is E = hν, where h is Planck's constant.
Photoelectric Cell Functioning
- For current to flow in a photoelectric cell, the energy of incoming photons must equal or exceed the energy required to release electrons from the metal.
Quantum and Energy Packets
- An energy packet is referred to as a quantum, and its energy correlates directly with its frequency.
Threshold Frequency
- The minimum frequency of light required to produce a current in a photoelectric device is known as the threshold frequency.
Calculation of Photon Energy
- The energy of a photon of orange light with a wavelength of 600 nm is calculated to be approximately 3.32 × 10^-19 J using the relation E = hc/λ.
Electromagnetic Radiation
- Electromagnetic radiation consists of photons with distinct wavelengths and frequencies.
Atomic Line Spectra
- Every element has a unique atomic line spectrum, which arises from the emission of light at specific wavelengths and includes radiation that may fall outside the visible spectrum.
Energy Expressions in Quantum Physics
- Energy can be expressed in terms of Planck's constant through the equations E = hc/λ and E = hν.
Absorption of Energy by Atoms
- A photon must be absorbed by an electron for energy transfer, with the energy of the photon needing to match or exceed the energy difference between two states for this to occur.
Bohr Model of Hydrogen Atom
- In the Bohr model, an electron's energy is quantized into discrete levels associated with fixed orbits around the nucleus.
- The quantum number n indicates the specific energy level, with lower n values corresponding to lower energy states closer to the nucleus.
Emission of Radiation
- When an electron transitions between energy levels, such as from n = 4 to n = 1, it emits radiation which can be in the ultraviolet region, with specific wavelengths like 97.3 nm.
Energy Absorption Criteria
- For an atom to absorb radiation, the energy of the incoming photon must exactly match the energy difference between two specific energy levels.
Quantum Number Characteristics
- The quantum number n indicates the energy level of electrons in an atom and can only take positive, whole-number values.
- Higher values of n correspond to higher energy states and greater distance from the nucleus.
Change in Energy Calculation
- The change in energy (ΔE) for an electron in the n = 3 energy level transitioning to n = 2 is 3.03 × 10^-19 J.
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Description
This quiz covers key concepts related to the quantization of energy, including definitions and important principles like the photoelectric effect. Test your understanding of the foundational ideas in quantum mechanics through interactive flashcards. Perfect for students studying physics or related fields.
