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Concept module

Photoelectric Effect

Use one compact lamp-to-metal bench to see why light frequency sets electron emission, why intensity alone fails below threshold, and how stopping potential reads the electron energy honestly.

The simulation shows a light-frequency rail across infrared, visible light, and ultraviolet, plus a compact lamp-to-metal bench with an emitter plate, a collector plate, and animated electron packets when emission occurs. Optional overlays mark the threshold frequency, the intensity/current distinction, the retarding or aiding collector field, and a compact energy-budget card. The readout card summarizes band, photon energy, work function, maximum kinetic energy, stopping potential, available current, collected current, and collector voltage. At display t = 0 s, 0.95 PHz light gives photon energy 3.93 eV against work function 2.3 eV, so emitted electrons can leave with max kinetic energy 1.63 eV and stopping potential 1.63 V. The intensity sets an available current of 1 arb., while collector bias 0.4 V leaves 1 arb. reaching the collector.

Interactive lab

Keep the stage, graph, and immediate control feedback in one working view.

Time

0.00 s / 4.80 sLiveThreshold, stopping-potential, and intensity sweeps stay parameter-based while the time rail inspects the same emitted-electron packets and collector bias honestly.
0.00 s4.80 s

Photoelectric Effect

A compact lamp-to-metal bench keeps beam frequency, intensity, work function, and collector bias tied to the same emitted-electron story.

Live setup
Live photoelectric benchlight frequencyInfraredvisibleUltravioletf00.95 PHzlampmetalcollectorUltravioletphiintensity1 arb.changes count, not KEcollector aids collectionVstop = 1.63 Venergy budgethf = 3.93 eVphi = 2.3 eVKmax = 1.63 eVcollector voltage-4.5 V0+1.5 V-Vstop0.4 VEmission statebandUltraviolethf3.93 eVphi2.3 eVKmax1.63 eVVstop1.63 VIavail1 arb.Icol1 arb.Vc0.4 VThreshold f0 = 0.56 PHz.Above threshold, intensity changes count while frequency sets electron energy.collector aids collection

Graphs

Switch graph views without breaking the live stage and time link.

Energy budget vs frequency

Compares photon energy, the work-function barrier, and the leftover kinetic energy on the same frequency axis.

frequency (PHz): 0.3 to 1.8energy (eV): 0 to 16
Photon energy hfWork function phiMax KE
Energy budget vs frequencyCompares photon energy, the work-function barrier, and the leftover kinetic energy on the same frequency axis.0.30.550.81.051.31.551.80481216frequency (PHz)energy (eV)
Hover or scrub to link the graph back to the stage.frequency (PHz) / energy (eV)

Controls

Adjust the physical parameters and watch the motion respond.

0.95 PHz

Sets the photon's energy and visible/UV band.

1 arb.

Changes photon flux and available current.

2.3 eV

Changes the metal's threshold barrier.

0.4 V

Applies an aiding or retarding field across the plates.

More tools

Secondary controls, alternate presets, and less-used toggles stay nearby without crowding the main bench.

Show

More presets

Presets

Predict -> manipulate -> observe

Keep the active prompt next to the controls so each change has an immediate visible consequence.

Graph readingPrompt 1 of 3
Making the collector voltage more negative trims the collected current, and the cutoff happens near the stopping potential shown in the readout.

Try this

Open the collector-voltage sweep and hover near the current cutoff.

Equation map

See each variable before you move it.

Select a symbol to highlight the matching control and the graph or overlay it most directly changes.

Light frequency
0.95 PHz

Moves the beam from infrared through visible into ultraviolet and changes the per-photon energy.

Graph: Energy budget vs frequencyGraph: Collected current vs collector voltageOverlay: Threshold gateOverlay: Energy budget

Equations in play

Choose an equation to sync the active symbol, control highlight, and related graph mapping.

More tools

Detailed noticing prompts, guided overlays, and challenge tasks stay available without taking over the main bench.

Hide

What to notice

Use these prompts to separate threshold, intensity, and stopping-voltage ideas without leaving the same compact bench.

Graph readingPrompt 1 of 3
Making the collector voltage more negative trims the collected current, and the cutoff happens near the stopping potential shown in the readout.

Try this

Open the collector-voltage sweep and hover near the current cutoff.

Why it matters

It turns the stopping-potential idea into a measurable quantity on the same bench.
Control: Collector voltageGraph: Collected current vs collector voltageOverlay: Stopping fieldOverlay: Energy budget

Guided overlays

Focus one overlay at a time to see what it represents and what to notice in the live motion.

4 visible

Overlay focus

Threshold gate

Marks the frequency threshold and the work-function barrier together.

What to notice

  • Emission turns on only when the frequency marker crosses f0 for the current metal.

Why it matters

It keeps the threshold idea visual instead of turning it into a detached formula.

Control: Light frequencyControl: Work functionGraph: Energy budget vs frequencyEquationEquation

Challenge mode

Use the same emission bench for compact threshold and stopping-potential targets.

0/2 solved
TargetCore

1 of 5 checks

Brightness is not enough

Starting from Bright but still below threshold, keep the beam bright while proving the collector current can stay essentially zero.
Graph-linkedGuided start2 hints

Suggested start

Use intensity as a distraction and check the threshold barrier instead.
Pending
Open the Current vs intensity graph.
Energy budget vs frequency
Matched
Keep the Threshold gate visible.
On
Pending
Keep intensity between 1.45 arb. and 1.8 arb..
1 arb.
Pending
Keep frequency phz between 0.3 PHz and 0.4 PHz.
0.95 PHz
Pending
Keep collector current between 0 arb. and 0.02 arb..
1 arb.

The checklist updates from the live simulation state, active graph, overlays, inspect time, and compare setup.

At display t = 0 s, 0.95 PHz light gives photon energy 3.93 eV against work function 2.3 eV, so emitted electrons can leave with max kinetic energy 1.63 eV and stopping potential 1.63 V. The intensity sets an available current of 1 arb., while collector bias 0.4 V leaves 1 arb. reaching the collector.
Equation detailsDeeper interpretation, notes, and worked variable context.

Photon energy

Higher frequency means more energy per photon.

Light frequency 0.95 PHz

Threshold frequency

The work function sets the minimum frequency needed for emission.

Light frequency 0.95 PHz Work function 2.3 eV

Maximum emitted-electron energy

Any photon energy above the work function becomes electron kinetic energy.

Light frequency 0.95 PHz Work function 2.3 eV

Stopping potential

The retarding voltage needed to stop the fastest electrons reads the maximum kinetic energy.

Collector voltage 0.4 V

Emission rate trend

Above threshold, brighter light raises the available current more than it raises individual electron energy.

Intensity 1 arb.

Progress

Not startedMastery: NewLocal-first

Start exploring and Open Model Lab will keep this concept's progress on this browser first. Challenge mode has 2 compact tasks ready. No finished quick test, solved challenge, or completion mark is saved yet.

Let the live model runChange one real controlOpen What to notice

Try this setup

Copy the live bench state and reopen this concept with the same controls, graph, overlays, and compare context.

Stable links

Starter track

Step 1 of 50 / 5 complete

Modern Physics

Next after this: Atomic Spectra.

1. Photoelectric Effect2. Atomic Spectra3. de Broglie Matter Waves4. Bohr Model+1 more steps

This concept is the track start.

See next concept

Short explanation

What the system is doing

The photoelectric effect is the compact modern-physics case where light frequency matters more deeply than brightness. If each photon's energy stays below the metal's work function, no electrons leave the surface at all, even when the beam is made brighter.

This module keeps one lamp, one metal plate, one collector plate, and one linked set of readouts. Frequency, intensity, work function, collector voltage, worked examples, quick tests, overlays, and challenge checks all refer to that same honest emission bench instead of splitting into separate stories.

Key ideas

01Below the threshold frequency, raising intensity alone still gives no emitted electrons.
02Above threshold, frequency changes the electron energy, while intensity mainly changes how many electrons are emitted per second.
03The threshold frequency comes from the work function through f_0 = phi / h.
04A negative collector voltage can stop even emitted electrons, and the stopping potential reads the maximum kinetic energy.

Live photoelectric checks

Solve the exact state on screen.

Use the current light and metal settings directly from the live bench. The same controls drive the stage, graphs, overlays, and worked result.
Live valuesFollowing current parameters

For the current frequency 0.95 PHz and work function 2.3 eV, does emission happen and what kinetic-energy budget remains?

Light frequency

0.95 PHz PHz

Wavelength

315.57 nm nm

Work function

2.3 eV eV

1. Convert frequency to photon energy

With , the photon energy is .

2. Compare with the work function

The metal needs , so the current threshold is .

3. Read the leftover energy

That leaves , so the live bench says emission occurs.

Current emission state

Because exceeds the work function 2.3 eV, electrons leave the surface with a maximum kinetic energy of 1.63 eV.

Threshold checkpoint

Two beams hit the same metal. Beam A is bright red light below threshold. Beam B is dimmer violet light above threshold. Which beam ejects electrons, and why?

Prediction prompt

Answer from photon energy first, not from brightness alone.

Check your reasoning

Beam B ejects electrons because its frequency gives each photon enough energy to clear the work function. Beam A does not, even if it is brighter.
The comparison is about per-photon energy, not just total light power. Intensity changes the photon flux, but threshold frequency decides whether emission can begin.

Common misconception

If you make sub-threshold light bright enough, electrons eventually absorb enough wave energy to escape.

In this bounded model, each emitted electron still needs one photon with enough energy to clear the work function barrier.

Brightness raises the flux of photons, but if each photon is still below threshold, the collector current remains zero.

Quick test

Reasoning

Question 1 of 4

Answer from the live light-on-metal logic, not from disconnected slogans.

Bright red light below threshold hits a metal surface. What should happen?

Choose one answer to reveal feedback, then test the idea in the live system if a guided example is available.

Accessible description

The simulation shows a light-frequency rail across infrared, visible light, and ultraviolet, plus a compact lamp-to-metal bench with an emitter plate, a collector plate, and animated electron packets when emission occurs.

Optional overlays mark the threshold frequency, the intensity/current distinction, the retarding or aiding collector field, and a compact energy-budget card. The readout card summarizes band, photon energy, work function, maximum kinetic energy, stopping potential, available current, collected current, and collector voltage.

Graph summary

The energy-balance graph compares photon energy, work function, and maximum kinetic energy on one frequency axis. The collector-sweep graph shows collected current against collector voltage with the available current as a reference, and the intensity-sweep graph keeps intensity linked to current scale rather than to electron energy.