Domain: Natural Science — Physics
Target concept: The zinc plate on the electroscope, when exposed to ultraviolet light, causes discharge.

Video generation prompt: A negatively charged gold-leaf electroscope, equipped with a zinc plate at its top, is illuminated by a lamp that alternately emits light in the visible and ultraviolet ranges at the same distance.

Evaluation guide:
(i) Target concept: Photoelectric discharge of a negatively charged electroscope via UV-induced electron emission from zinc.
Minimum mechanism: Zinc must be present and illuminated; UV photons must exceed zinc's work function (~4.3 eV, wavelength below ~290 nm); emitted electrons carry away negative charge, reducing leaf repulsion; this charge loss is not restored by subsequent visible-light exposure, since visible photons (wavelength above ~400 nm) lack the energy to eject electrons or add charge back; leaves respond to UV exposure with convergence that persists once the light source returns to the visible range.
(ii)Storyline: Frame 0–2s: Stable shot of diverged gold leaves under visible light; zinc plate clearly attached, lamp emits warm/white light. Frame 2–4s: Lamp visibly switches mode (e.g., glow shifts to violet, filter rotates in, or icon changes); leaves begin smooth, continuous convergence. Frame 4–6s: UV mode sustained; leaves reach a fully converged (or maximally converged) position. Frame 6–8s: Lamp switches back to visible mode; the converged leaf position holds steady, since the charge carried away during UV exposure is not restored by visible light. Frame 8–10s: Visible mode sustained; leaves remain at their converged position, confirming that only UV, not visible light, altered the electroscope's charge. Throughout: Fixed viewpoint, no occlusion, no external intervention, no lighting discontinuity.

Manual:
Experimental Procedure
1. Place a negatively charged gold-leaf electroscope with zinc plate mounted on top.
2. Position a lamp at fixed distance, emitting visible light first.
3. Switch lamp to ultraviolet emission mode.
4. Observe gold-leaf behavior across both modes.
Observation of Experimental Phenomena
During visible light: gold leaves remain diverged.
During ultraviolet light: gold leaves gradually collapse (converge).
Summary of Experimental Principles
Ultraviolet light causes photoelectric emission from the zinc plate, discharging the electroscope; visible light lacks sufficient photon energy to eject electrons, so no discharge occurs.

Prompt Grounding rubric:
level_1: None of the required setup elements are shown together: no gold-leaf electroscope appears, or no zinc plate sits on top of it, or no lamp is shown illuminating it, or the lamp only ever shows one lighting mode with no alternation, or the leaves never appear diverged at the outset.
level_2: At least one core element appears (the electroscope, or the lamp, or the zinc plate), but the setup is incomplete: the zinc plate is missing from the electroscope's top, or the lamp shows only a single spectral appearance throughout (never switching), or the leaves are not diverged in the opening shot, or there is no alternation sequence between lighting modes at all.
level_3: All core elements appear correctly arranged: a negatively charged electroscope with its gold leaves visibly diverged at the start, a zinc plate mounted on top of it, and a lamp held at a fixed distance that visibly switches between two distinct lighting appearances (e.g., a violet/UV-tinted glow and a white/yellow visible-light glow), with the switch shown through a visible cue such as a color change, a filter moving into place, or an on-screen label.
level_4: Everything at the 3-point level holds, and further: the lamp keeps the same distance and orientation to the electroscope across both lighting modes; the zinc plate stays fully visible and attached the entire time; the gold leaves are never blocked from view; no hands, tools, or extraneous props enter the shot during the mode switches; and the two lamp appearances are distinguishable by their look alone (glow color, halo, etc.) rather than relying only on text captions.
level_5: Everything at the 4-point level holds, and further: each lamp mode is self-evidently different from its visual properties alone (e.g., a violet-tinted glow versus a broad white/yellow glow), with no on-screen arrows, UI overlays, or explanatory text appearing at any point; the entire sequence contains only the electroscope, its zinc plate, the lamp, and a plain, uncluttered background, all held in a stable, unchanging composition throughout.

Scientific and Causal Correctness rubric:
level_1: No causal link between light and leaf motion is shown: the gold leaves stay rigidly diverged (or collapsed) no matter which lighting mode is active, or the zinc plate shows no response to either light type, or the lamp's two modes produce identical leaf behavior.
level_2: The leaves do move at some point, but not tied to the UV/visible distinction: motion happens at a random moment unrelated to the mode switch, or the leaves converge during the visible-light phase instead of the UV phase, or they re-diverge after the lamp returns to visible mode (which would incorrectly imply the visible light restored lost charge).
level_3: The gold leaves converge specifically once the lamp switches into its UV-appearing mode, with the motion visibly starting within the same shot as that switch; the zinc plate stays illuminated throughout; after the lamp later returns to its visible-appearing mode, the leaves hold their converged position rather than opening back up.
level_4: Everything at the 3-point level holds, and further: the convergence itself unfolds gradually rather than snapping instantly into place; no additional convergence or divergence occurs while the visible-light mode is showing; the zinc plate shows no glow, spark, or color change under either light: it stays visually inert metal throughout.
level_5: Everything at the 4-point level holds, and further: if the lamp cycles into its UV-appearing mode more than once, the leaves show no illogical reopening beforehand, and any further convergence (if the leaves had not already reached their limit) again begins only within a UV-mode shot; the lamp's visual indicator for its current mode (glow color, halo, or on-screen cue) stays unambiguous and distinct between the two modes at every point, never overlapping so a viewer could mistake one mode's appearance for the other's.

Spatiotemporal Consistency rubric:
level_1: Severe continuity break: the electroscope or lamp is suddenly missing from a frame and then present again in a different spot, the lamp's position jumps discontinuously, the gold leaves snap instantly between different divergence angles with no visible transition, the overall brightness swings from near-black to blown-out white with no transition, or the zinc plate detaches from the electroscope mid-clip.
level_2: Multiple noticeable disruptions: the leaves or zinc plate are blocked from view for a long stretch, the lamp's position drifts sideways by more than the width of the electroscope's base, the footage flickers or strobes, or the cast shadow swings to a new direction with no matching movement of the lamp.
level_3: The electroscope base, zinc plate, gold leaves, and lamp stay in a stable spatial arrangement relative to each other: nothing disappears, snaps to a different position, or changes size unexpectedly; the overall lighting stays even across the clip with no sudden global shift; leaf motion looks physically smooth rather than rigid or rubbery; there's no tearing or ghosting that makes the objects hard to recognize.
level_4: Everything at the 3-point level holds, and further: the lamp and electroscope keep a consistent relative depth (no parallax drift between them); neither the leaves nor the zinc plate show fish-eye-style warping; the footage runs smoothly with no frozen or repeated frames; and the shadow cast by the lamp stays aligned with the lamp's actual position and the leaves' geometry throughout.
level_5: Everything at the 4-point level holds, and further: the camera viewpoint never pans, tilts, zooms, or drifts; no motion blur obscures the leaf angle or the zinc plate's attachment point; no glare or specular highlight washes out visible surface detail on the zinc plate or gold leaves; and the background stays plain and unchanging behind the electroscope throughout.