Quantum photoelectric and line spectra explorer
Explore photoelectric observations, stopping-potential graphs and atomic spectral lines to connect quantum evidence with equations.
Learning goals
- Use photon energy and momentum and analyse the photoelectric effect.
- Analyse atomic energy levels and emission or absorption spectra.
Sodium lit by light of frequency 7.0 × 10¹⁴ Hz at 60% intensity, collector at 0.00 V. Electrons are emitted; the current is 20.73 nA.
- Photon energy, hf
- 2.89 eV
- Work function, Φ
- 2.36 eV
- Wavelength, λ
- 428 nm
- Current, I
- 20.73 nA
- Last transition
- —
- Photon energy, ΔE
- — eV
- Wavelength, λ = hc / ΔE
- — nm
- Series
- —
Try this
0 of 4 doneShine very bright light below the threshold frequency, then dim light above it. (not done yet)
Bright light below the threshold frees no electrons; dim light above it does at once. One photon gives one electron its energy hf.
Find the stopping potential at four frequencies and record each one. (not done yet)
KEmax = hf − Φ: the gradient of your line is the Planck constant (× 10⁻³³ here) and the y-intercept is −Φ.
Make a hydrogen atom emit its red line (656 nm). (not done yet)
n = 3 → 2: ΔE = 1.89 eV, so λ = hc / ΔE = 656 nm. All transitions down to n = 2 form the Balmer series.
In the absorption spectrum, make a dark line where you saw a bright one. (not done yet)
An atom absorbs only the photons it could emit: the same energy gap gives the same wavelength.
You’ve tried every task.
Your readings
| # | f / 1014 Hz | Vs / V | KEmax / 10−19 J | Remove |
|---|---|---|---|---|
| No readings yet. Set up a measurement, then record it. | ||||