Emission and Absorption Spectra - AP Physics 2

What is an emission spectrum?

A spectrum of frequencies emitted by an atom or molecule. Shows specific wavelengths of light emitted when electrons drop to lower energy levels.
What type of light source is ideal for observing a continuous spectrum?

Incandescent bulb or blackbody radiator. Thermal sources emit broad, continuous wavelength distribution.
What is the Balmer series associated with?

Emission spectrum of hydrogen. Series of visible lines from electron transitions to $n=2$ level.
What type of spectrum is typically used in chemical analysis?

Both emission and absorption spectra. Combined techniques provide comprehensive elemental and quantitative analysis.
What is quantified by the intensity of spectral lines?

The concentration of elements. Line intensity correlates with number of atoms present.
What is a spectrograph?

An instrument that records a spectrum photographically. Device that captures and records spectral data permanently for analysis.
Which spectrum is produced by incandescent light bulbs?

Continuous spectrum. Hot tungsten filament produces thermal radiation across all visible wavelengths.
What is the primary use of emission spectra in laboratories?

To identify elements present in a sample. Bright emission lines reveal elemental composition through characteristic wavelengths.
What is an absorption spectrum?

A spectrum showing dark lines or bands due to absorption of light. Occurs when electrons absorb specific wavelengths, creating gaps in continuous spectrum.
What is the significance of the Rydberg formula?

Calculates wavelengths of spectral lines of hydrogen. Mathematical formula predicting hydrogen spectral line wavelengths accurately.
What is the purpose of using a monochromator in spectroscopy?

To isolate specific wavelengths of light. Device selects narrow wavelength bands from broader spectrum.
What type of spectrum is observed when light passes through a cool gas?

Absorption spectrum. Cool gas atoms absorb specific wavelengths from continuous background light.
State the condition for observing an emission spectrum.

Excited electrons fall to lower energy levels. Energy release during electron transitions produces characteristic photons.
Which spectrum is used to identify elements in stars?

Absorption spectrum. Dark absorption lines reveal elemental composition of stellar atmospheres.
State the condition for observing an absorption spectrum.

Electrons absorb energy and move to higher levels. Energy absorption promotes electrons to higher quantum states.
What is the Paschen series associated with?

Infrared emission spectrum of hydrogen. Series of IR lines from electron transitions to $n=3$ level.
What is the importance of spectral lines?

They identify elements and compounds. Each element produces unique spectral fingerprint for identification.
What type of spectrum does a hot, low-density gas emit?

Emission spectrum. Low-density gas atoms emit discrete wavelengths when electrons transition downward.
What type of spectrum does a hot, dense object emit?

Continuous spectrum. Dense objects emit all wavelengths continuously due to thermal motion.
In what type of spectrum do Fraunhofer lines appear?

Absorption spectrum. Dark lines in solar spectrum discovered by Joseph von Fraunhofer.
What feature distinguishes a bright-line spectrum?

Bright lines indicating emitted wavelengths. Emission spectrum shows bright lines against dark background.
Which spectral lines are visible when sodium vapor is heated?

Bright yellow lines. Sodium's characteristic D-lines appear as intense yellow doublet.
What is the result of electrons transitioning between energy levels?

Emission or absorption of photons. Energy differences between levels determine photon wavelength emitted or absorbed.
What type of spectrum results from a prism dispersing sunlight?

Continuous spectrum. Prism disperses white light into complete rainbow without gaps.
Identify the term: spectrum with dark lines on bright background.

Absorption spectrum. Dark lines indicate absorption of specific wavelengths from continuous spectrum.
What is the primary difference between emission and absorption spectra?

Emission shows bright lines; absorption shows dark lines. Emission adds light at specific wavelengths; absorption removes it.
What causes the dark lines in an absorption spectrum?

Absorption of specific wavelengths by a substance. Electrons absorb photons of specific energies, removing those wavelengths from spectrum.
What is the Lyman series associated with?

Ultraviolet emission spectrum of hydrogen. Series of UV lines from electron transitions to $n=1$ ground state.
What region of the electromagnetic spectrum do Balmer lines appear in?

Visible region. Balmer series produces visible light from hydrogen atom transitions.
What does a spectrometer measure?

Intensity of light at different wavelengths. Device separates and measures light intensity across electromagnetic spectrum.
Identify the term: spectrum with bright lines on dark background.

Emission spectrum. Bright lines indicate emission of specific wavelengths against dark background.
Identify the instrument used to view spectra.

Spectroscope. Optical instrument that disperses light into component wavelengths for observation.
Which spectrum is used in neon signs?

Emission spectrum. Excited gas atoms emit characteristic colors when electrons drop energy levels.
What is the role of a diffraction grating in spectroscopy?

To separate light into its component wavelengths. Grating diffracts light into distinct wavelengths for spectral analysis.
Identify the spectrum: Sunlight passing through Earth's atmosphere.

Absorption spectrum. Atmospheric gases absorb specific wavelengths from continuous sunlight.
What is the primary use of absorption spectra in astronomy?

To determine the composition of stars and planets. Spectral lines act as fingerprints identifying specific elements remotely.
Identify the region of the electromagnetic spectrum used in X-ray spectroscopy.

X-ray region. High-energy X-rays probe inner electron shells of atoms.

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