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AP Physics 2: Algebra-Based Practice Quiz: Emission and Absorption Spectra

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 10 questions to check your progress.

Question 1 of 10

According to the provided model, what occurs when an atom absorbs a photon?

All Questions (10)

According to the provided model, what occurs when an atom absorbs a photon?

A) The atom's nucleus gains kinetic energy.

B) An electron transitions to a higher atomic energy state.

C) The atom emits a photon of a different frequency.

D) The atom's nucleus and electron are separated.

Correct Answer: B

The content states that energy transfer occurs when photons are absorbed, and this corresponds to transitions between two energy states. Absorption involves gaining energy, so an electron moves to a higher energy state.

An atom has three allowed energy states: E₁, E₂, and E₃, with E₁ < E₂ < E₃. If an electron is in the ground state E₁, which of the following photon energies could be absorbed by the atom?

A) E₂

B) E₃ - E₂

C) E₂ - E₁

D) Any energy greater than E₁

Correct Answer: C

The content specifies that energy can only be absorbed if it corresponds to the energy difference between two atomic energy states. For an electron starting in state E₁, it can only transition to E₂ or E₃. The energy required for the transition to E₂ is the difference, E₂ - E₁.

A photon with an energy of 4.5 eV is directed at an atom. The atom's possible energy transitions from its current state are 2.0 eV and 4.0 eV. What is the most likely outcome?

A) The atom will absorb the photon and transition by 4.0 eV, releasing the extra 0.5 eV.

B) The atom will absorb the photon and the electron will become unbound.

C) The atom will not absorb the photon.

D) The atom will absorb 4.0 eV of the photon's energy and the photon will continue with 0.5 eV.

Correct Answer: C

According to the provided content, an atom can only absorb energy if the amount corresponds exactly to the energy difference between two atomic energy states. Since 4.5 eV does not match either of the possible transition energies (2.0 eV or 4.0 eV), the photon will not be absorbed.

When an electron in an atom transitions from a higher energy state to a lower energy state, what is produced?

A) A photon with a continuous range of possible frequencies.

B) A photon with an energy equal to the higher energy state.

C) A photon of a single frequency.

D) Two photons, each with half the energy of the transition.

Correct Answer: C

The content states that transitions between two energy states correspond to the emission of a photon of a single frequency. This is because the energy difference is a specific, discrete value.

An atom absorbs a photon of wavelength λ₁ to transition from energy state A to energy state B. It then emits a photon of wavelength λ₂ to transition back from state B to state A. How does the energy of the first photon (E₁) relate to the energy of the second photon (E₂)?

A) E₁ > E₂

B) E₁ < E₂

C) E₁ = E₂

D) The relationship cannot be determined without knowing the energy states.

Correct Answer: C

The energy absorbed or emitted must correspond to the energy difference between the two states. Since the transition from A to B and the transition from B to A have the same energy difference (ΔE = E_B - E_A), the energy of the absorbed photon must be equal to the energy of the emitted photon.

The interaction involving the emission or absorption of photons is modeled as an energy transfer within a system. What are the components of this atomic system as described in the text?

A) A proton and a neutron.

B) An electron and a positron.

C) A nucleus and an electron.

D) Multiple electrons in an electron cloud.

Correct Answer: C

The provided content explicitly states that the atom is modeled as a system consisting of a nucleus and an electron for the purpose of describing energy transfer via photons.

Which principle best explains why the emission spectrum of a particular element consists of discrete, bright lines at specific wavelengths rather than a continuous spectrum?

A) Photons can have any amount of energy.

B) Atomic energy states are quantized, allowing only specific energy transitions.

C) The nucleus of an atom repels emitted photons.

D) Electrons continuously lose energy as they orbit the nucleus.

Correct Answer: B

The content explains that photons are emitted only when an electron transitions between two specific energy states. Because these states have discrete energy values, the energy difference is also a discrete value, leading to the emission of photons of a single frequency and wavelength. This results in a line spectrum, not a continuous one.

If an atom undergoes a transition that emits a high-energy photon, how would the frequency and wavelength of this photon compare to a photon emitted from a lower-energy transition in the same atom?

A) It would have a lower frequency and a longer wavelength.

B) It would have a higher frequency and a shorter wavelength.

C) It would have a higher frequency and a longer wavelength.

D) It would have a lower frequency and a shorter wavelength.

Correct Answer: B

The content links the energy of a transition to a photon of a single frequency and wavelength. The energy of a photon is directly proportional to its frequency (E=hf) and inversely proportional to its wavelength (E=hc/λ). Therefore, a high-energy transition results in a high-frequency, short-wavelength photon.

The process of an atom absorbing a photon and the process of an atom emitting a photon are similar in that both

A) result in the atom moving to a lower energy state.

B) involve an energy transfer equal to the difference between two atomic energy states.

C) can occur with a photon of any energy.

D) result in the atom moving to a higher energy state.

Correct Answer: B

The provided content establishes that for both absorption and emission, the amount of energy transferred must correspond exactly to the energy difference between two atomic energy states. Absorption leads to a higher state, while emission results from a transition to a lower state.

An electron in an excited state E₃ can transition directly to the ground state E₁ by emitting a single photon, or it can transition to an intermediate state E₂ and then to E₁. Which statement correctly describes the frequencies of the photons involved (f₃₁ for the direct transition, f₃₂ for the first step, and f₂₁ for the second step)?

A) f₃₁ = f₃₂ - f₂₁

B) f₃₁ = f₃₂ + f₂₁

C) f₃₁ = f₃₂ = f₂₁

D) f₃₁ = (f₃₂ + f₂₁)/2

Correct Answer: B

Energy must be conserved. The total energy difference for the direct transition (E₃ - E₁) must equal the sum of the energy differences for the two-step transition ((E₃ - E₂) + (E₂ - E₁)). Since photon energy is directly proportional to frequency (E=hf), the frequencies must also be additive: hf₃₁ = hf₃₂ + hf₂₁, which simplifies to f₃₁ = f₃₂ + f₂₁.