Domain: Engineering — Electrical Engineering
Target concept: Photoconductive effect in the light-dependent resistor used for controlling LEDs

Video generation prompt: In a desktop battery circuit, a photoresistor is connected in series with a light-emitting diode (LED). When the desk lamp is brought close, the light changes, then is blocked by a hand, and is subsequently removed again.

Evaluation guide:
(i) Target concept: Photoconductive effect in LDR governs current flow in a series LED circuit; minimum mechanism: incident light intensity on photoresistor must modulate its resistance, which must be the dominant variable controlling LED current (no parallel paths, no voltage regulation, no LED burnout).
(ii) Storyline: (1) Initial state: lamp distant → photoresistor dark → high resistance → LED OFF; (2) Lamp approaches → increasing illumination → decreasing photoresistor resistance → rising current → LED transitions to ON and remains stably lit; (3) Hand enters frame and fully occludes lamp-to-photoresistor path → illumination drops to near-zero → resistance surges → current collapses → LED transitions to OFF and remains stably off; (4) Hand withdraws fully → illumination restored → resistance drops → current rises → LED transitions back to ON and remains stably lit; perspective: fixed frontal tabletop view showing full circuit, lamp, and hand interaction zone; all critical components (photoresistor surface, LED face, lamp bulb, hand palm/fingers) must remain unoccluded during their causal action windows.

Manual:
Experimental Procedure
1. Place a battery-powered desktop circuit with photoresistor and LED wired in series.
2. Bring desk lamp close to photoresistor to illuminate it.
3. Block lamp light from photoresistor using hand.
4. Remove hand to restore illumination.
Observation of Experimental Phenomena
LED turns ON when lamp approaches, turns OFF when hand blocks light, and turns back ON when hand is removed.
Summary of Experimental Principles
Photoconductive effect: photoresistor resistance decreases under light → circuit current increases → LED lights up. Resistance increases in darkness → current drops → LED turns off.

Prompt Grounding rubric:
level_1: None of the required elements are shown (no photoresistor, no LED, no desk lamp, no hand), or they appear in a setup that plainly contradicts the prompt, e.g., the LED is not wired to the photoresistor at all, the lamp is aimed away from the photoresistor, or the hand never approaches the lamp-to-photoresistor path.
level_2: Only some of the four required elements (photoresistor, LED, desk lamp, hand) appear together, with at least one missing; or all four appear but their arrangement contradicts the prompt, e.g., the lamp is positioned so its light cannot reach the photoresistor, the hand blocks something unrelated to the light path, or the LED is not visibly wired in series with the photoresistor.
level_3: The photoresistor, LED, desk lamp, and hand are all visible; the photoresistor and LED are connected in series through visible wiring or direct contact; the lamp is positioned so its light could reach the photoresistor; the hand is positioned near the lamp-to-photoresistor path; but the order of events is missing or scrambled, e.g., the hand blocks the light before the lamp ever approaches, or the hand withdraws before it has blocked anything.
level_4: All four elements are present and correctly arranged, and the three actions (the lamp approaching the photoresistor, the hand moving in to block the light path, and the hand withdrawing) occur in the correct order; however, at least one of these actions lacks smooth visual continuity, such as the lamp's approach jumping partway through its motion, or the hand appearing or disappearing abruptly instead of moving continuously into or out of frame.
level_5: All four elements are present and correctly arranged; the lamp approaches the photoresistor with continuous motion, the hand moves continuously into the light path to block it, and the hand then moves continuously away; all three actions occur in the correct order (approach, block, remove) with no jump cuts, no object popping in or out of frame, and full visibility of the photoresistor, LED, lamp bulb, and hand throughout their respective actions.

Scientific and Causal Correctness rubric:
level_1: The LED stays constantly off or constantly on no matter what the lamp or hand does; or it changes state with no lamp or hand action nearby; or the photoresistor shows no visible response to light at all; or the LED's behavior runs backward from the photoconductive effect, for example it gets brighter exactly when the hand blocks the lamp's light.
level_2: The LED changes state, but in the wrong direction for at least one transition, e.g., it turns on when the hand blocks the light (it should turn off) or turns off as the lamp approaches (it should turn on); or a state change happens with no matching lamp/hand action; or only one of the two expected transitions (on-then-off, or off-then-on) occurs at all.
level_3: The LED turns on as the lamp approaches and turns off as the hand blocks the light, both in the correct direction, but the final off-to-on transition when the hand is withdrawn is missing, happens well after the hand has cleared the path, or is too unclear (poor contrast or partial occlusion) to confirm; or a state change happens visibly before the lamp finishes approaching or after the hand starts withdrawing, breaking the causal link to the action.
level_4: The LED shows all three correct transitions (off to on as the lamp approaches, on to off as the hand blocks the light, and off to on again as the hand withdraws), each one clearly visible and lining up with its corresponding action; but one of the three states (off, on, or the second on) is shown so briefly, or flickers so much, that its stability can't be confirmed.
level_5: The LED shows three clearly distinguishable, stable states tied directly to the three actions: it turns on and stays on once the lamp is close, turns off and stays off for the entire time the hand blocks the light, and turns back on and stays on once the hand is fully withdrawn; there is no flicker, no ambiguous in-between brightness, and every transition happens only during its corresponding action and not before or after.

Spatiotemporal Consistency rubric:
level_1: Severe continuity breaks occur: the photoresistor or LED vanishes and reappears; the lamp or hand jumps instantly to a new position or appears to pass through the tabletop; the overall lighting in the scene jumps abruptly with no connection to the lamp or hand; or a wire visibly ends in mid-air with no connection to anything.
level_2: Multiple noticeable problems appear together, for instance the photoresistor or LED is briefly hidden from view during one of the three key actions, and the lamp's or hand's motion looks noticeably choppy or jittery rather than smooth; or a shadow cast by the hand doesn't point toward the photoresistor the way it should given the lamp's position; or a wire appears to disconnect and reconnect with no physical cause.
level_3: There is at most one small flaw, for example the LED is briefly hidden from view for a moment during the hand's withdrawal, or the lamp's highlight on the photoresistor briefly fades during its approach; but nothing disappears and reappears outright, there is no jump in position, no broken wiring, and no shadow that clearly contradicts the lamp's position.
level_4: All objects stay continuously present in their expected relative positions; the lamp's and hand's motions are smooth and physically plausible; the hand's shadow falls across the photoresistor consistent with the lamp's position; the wiring stays visibly intact throughout; but there is one small inconsistency, such as the lamp's brightest spot drifting slightly off the photoresistor's surface during motion while still generally pointing at it.
level_5: There are no spatiotemporal flaws: the photoresistor and LED stay fully visible and in place the entire time; the lamp moves smoothly and stays aimed at the photoresistor throughout its approach; the hand's approach, block, and withdrawal are all smooth and fully visible; the hand's shadow consistently falls on the photoresistor exactly as the lamp's position would predict; the wiring never stretches, breaks, or disconnects; and any change in lighting in the scene is gradual, driven only by the lamp's distance and the hand's blocking.