Domain: Engineering — Electrical Engineering
Target concept: LED exhibits noticeable flicker visible to the naked eye, with low and unstable brightness, and no continuous steady-on state. The flicker frequency is consistent with the AC signal frequency.

Video generation prompt: Build a half-wave rectifier circuit (including a diode, resistor, and LED), connect it to an AC signal source, activate the signal source, and observe how the LED behaves over time.

Evaluation guide:
(i) Target concept: Half-wave rectification enabling unidirectional current flow through an LED driven by AC, resulting in perceptible flicker at line frequency.
Minimum mechanism: Diode must be oriented to conduct during one AC polarity; LED must be placed downstream of diode and upstream of return path; AC source must provide alternating voltage with sufficient amplitude to exceed LED forward voltage during conduction half-cycle; human visual persistence must be insufficient to fuse 50/60 Hz flashes into steady light.
(ii)Storyline: [Frame 0–2] Static overhead view shows all four components laid out in correct series order on breadboard; [Frame 3–4] Activation action occurs (switch flip/button press/power indicator lights); [Frame 5–10] LED exhibits strictly binary, rhythmic on/off behavior: each ON state is brief, low-brightness, and separated by equal-duration OFF states; no intermediate states, no brightness ramp, no afterimage; viewpoint remains fixed; lighting and shadows remain constant; all wiring stays intact and immobile.

Manual:
Experimental Procedure
1. Place diode, resistor, and LED in series on breadboard.
2. Connect diode anode to AC source output, cathode to resistor.
3. Connect resistor to LED anode; LED cathode to AC source return.
4. Turn on AC signal source (sine wave, 50/60 Hz, ~5–12 V).
Observation of Experimental Phenomena
LED flashes rhythmically at AC frequency — bright for half-cycle, fully off for half-cycle — with no steady glow or irregular flicker.
Summary of Experimental Principles
Half-wave rectification allows current only during positive half-cycles; LED conducts only when forward-biased by diode, resulting in visible 50/60 Hz flicker due to insufficient persistence of vision.

Prompt Grounding rubric:
level_1: No half-wave rectifier circuit is visible: at least two of the diode, resistor, LED, or AC signal source are missing from the frame, none of the components are wired to one another, the AC source is never switched on, or no LED is visible anywhere in the shot.
level_2: The diode and resistor are visible on the breadboard, but the LED is missing, unrecognizable, or obviously wired with its leads reversed; the AC signal source sits next to the breadboard but is not wired into the circuit; there is no visible switch flip, button press, or power-indicator light showing the source being turned on.
level_3: All four components are visible and identifiable: a diode with a visible cathode band, a resistor, an LED with distinguishable anode and cathode leads, and an AC signal source (e.g., a function generator with a sine-wave symbol or labeled output terminals). They are wired into a single series loop in the correct order: one AC source terminal into the diode, into the resistor, into the LED, and back to the other AC source terminal. A clear activation action is shown, such as a hand flipping a switch, pressing a button, or the source's own power light turning on.
level_4: Everything required for score 3 is shown, AND all four components sit at fixed positions side by side on the breadboard with no floating leads or disconnected clip ends, AND the diode's cathode band is oriented so that current passes through the diode toward the resistor and then arrives at the LED's anode lead (not its cathode); the diode and LED point the same way along the current path rather than being wired back-to-back. The activation action (switch flip, button press, or power light) is clearly shown happening before the LED shows any response.
level_5: Everything required for score 4 is shown, AND every component keeps its correct, recognizable form for the entire video: the diode's cathode band, the LED's flat-edge cathode side, the resistor's color bands or printed value, and the AC source's sine-wave icon or 'AC' label all stay visible and legible from start to finish; the diode-through-resistor-to-LED-anode wiring order established at score 4 is never reversed, swapped, or replaced with a back-to-back arrangement; every clip and connection point keeps the same position and contact throughout; the activation action and the LED's first visible response happen close together with no separate, unexplained waiting period shown in between.

Scientific and Causal Correctness rubric:
level_1: The LED stays continuously lit, stays completely dark for the whole clip, or blinks at a rate with no relation to the AC cycle (e.g., irregular strobing or a slow pulse of roughly one blink per second); there is no visible link between the LED's on/off state and the diode's orientation; brightness stays constant or rises and falls smoothly instead of switching between two states.
level_2: The LED does turn on and off at some point, but not in a steady rhythm: flashes vary in length or spacing, brightness wanders unpredictably instead of alternating cleanly between one dim level and darkness, and the LED is sometimes lit during the half-cycle in which the diode should be blocking current (reverse bias).
level_3: The LED lights only during one half of each AC cycle and goes fully dark during the other half, producing a regular, evenly spaced series of dim flashes; the lit portion and the dark portion of each cycle look about equal in length; the LED never holds a steady glow at any point in the video.
level_4: Everything required for score 3 is shown, AND the LED's ON flashes occur only during the half-cycle in which the diode conducts (forward bias), while the OFF phase lines up exactly with the half-cycle in which the diode blocks current (reverse bias); there is no glow, afterglow, or dim residual light visible during the OFF phase; each ON flash looks about the same brightness as the others, with none noticeably brighter or dimmer.
level_5: Everything required for score 4 is shown, AND the flash rate visibly matches the half-wave-rectified AC line frequency: the LED blinks once per AC cycle (about 50 or 60 times per second depending on the supply), reading as a rapid, evenly spaced series of distinct flashes rather than a slow blink or a smooth, flicker-free glow; during the OFF half-cycle the LED shows no visible light at all, with no faint glow or halo around it; the ON-phase brightness stays uniformly dim and steady with no color shift, dimming, or brightening within any single flash.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: the diode, resistor, LED, breadboard, or AC signal source jumps to a new position or vanishes between one frame and the next with no camera pan to explain it; the camera suddenly zooms, rotates, or cuts to a different angle; a wire connecting two components snaps apart or reattaches elsewhere with no hand visibly moving it; the ambient light on the workbench brightens, dims, or changes color abruptly partway through the clip, unrelated to the LED's own on/off blinking.
level_2: Moderate inconsistency: the breadboard shifts sideways or up/down by more than roughly a third of its height between shots without matching camera motion; the LED's apparent size or viewing angle changes suddenly rather than through continuous camera movement; a highlight or shadow cast by the breadboard or wires switches to the opposite side of an object between frames even though neither the camera nor the room light moved; something in the background (e.g., the bench surface or a wall behind the setup) flickers or disappears partway through the video.
level_3: The diode, resistor, LED, breadboard, and AC signal source stay in the same spatial arrangement relative to one another for the entire video: none of them jump, rotate, or change size unexpectedly; the camera holds one fixed, unzoomed framing with no cuts; every wire connected at the start of the clip remains attached at both ends throughout; the ambient light on the bench stays at a constant brightness, so any blinking visible in the shot is coming only from the LED itself and not from a change in room lighting.
level_4: Everything required for score 3 is shown, AND the activation action (e.g., a hand flipping a switch or pressing a button) moves through one continuous, unbroken motion with no stutter or freeze-frame; once the LED starts blinking, each transition between its lit and dark state is instantaneous rather than fading in or out; no ghosting, smearing, or motion blur ever makes it hard to tell which lead belongs to which component.
level_5: Everything required for score 4 is shown, AND there is no frame duplication or dropped frame that disrupts the regularity of the LED's blink pattern; viewing the angled breadboard produces no unnatural parallax shift; there is no lens flare, color fringing, or focus racking distracting from the components; every clip lead, solder joint, and breadboard contact keeps the same appearance and alignment in every frame, with no visible shaking, trembling, or flickering in the wires, breadboard, diode, resistor, or AC source; only the LED blinks, while everything else remains perfectly still throughout.