Domain: Engineering — Electrical Engineering
Target concept: LED exhibits no noticeable flicker (nearly imperceptible to the human eye) and maintains a continuous, steady illumination.

Video generation prompt: Build a full-wave rectifier circuit (including two diodes, a resistor, and an LED), connect it to an AC signal source, activate the signal source, and observe the state of the LED.

Evaluation guide:
(i) Target concept: Steady-state LED illumination enabled by full-wave rectification of AC input.
Minimum mechanism: AC source must be active; rectifier must conduct on both half-cycles; resulting pulsating DC must have sufficiently low ripple frequency and high enough average voltage to forward-bias LED continuously above its threshold; LED junction capacitance and human visual persistence must jointly suppress residual ripple perception.
(ii)Storyline: Frame 1–2: AC source symbol/waveform appears and activates (visible power indicator or waveform onset). Frame 3–4: Current path through both diodes becomes active (implied by circuit topology and timing). Frame 5–10: LED emits continuous, uniform light with zero detectable on/off transitions or intensity modulation, stable in position, color, and brightness. Perspective: Fixed overhead or 30° angled view showing full circuit layout; all components fully visible, no occlusion; lighting ensures clear visibility of LED emission and resistor bands.

Manual:
Experimental Procedure
1. Place AC signal source, two diodes, resistor, and LED on breadboard.
2. Wire diodes in full-wave rectifier configuration (opposing pairs across AC input).
3. Connect resistor and LED in series on rectified output path.
4. Activate AC source.
Observation of Experimental Phenomena
LED illuminates immediately upon activation and remains continuously lit with no visible flicker or pulsation.
Summary of Experimental Principles
Full-wave rectification converts both AC half-cycles into unidirectional current, enabling steady DC-like illumination of the LED — eliminating perceptible flicker seen in half-wave or unrectified AC operation.

Prompt Grounding rubric:
level_1: No full-wave rectifier circuit is visible: at least two of the four required parts (the center-tapped AC source, the two diodes, the resistor, and the LED) are missing, or no assembled circuit appears on the breadboard at all.
level_2: All four parts may appear on the breadboard, but the assembly is fundamentally wrong for a two-diode full-wave rectifier: for example, only one diode sits in the current path, the LED is wired directly across the raw AC source with no diode in series, the resistor is missing from the LED branch, or the AC source is not visibly wired into the diode network at all.
level_3: The AC source, two diodes, resistor, and LED are all visibly present and wired into one connected circuit on the breadboard, but the diode arrangement does not match a center-tapped full-wave layout: for example the two diodes are wired in series with each other instead of forming two separate half-cycle paths, or the LED sits on the AC input side rather than on the rectified output side.
level_4: All four components are present and correctly identified by form and placement: the AC source's two output leads (or a center-tapped secondary) feed two diodes wired as opposing conduction paths so each conducts on alternate half-cycles, and the resistor and LED sit in series on the shared DC output path; no component substitution is visible (no capacitor mistaken for the resistor, no incandescent bulb mistaken for the LED).
level_5: All four components are present, correctly placed, and unambiguously identifiable: the AC source displays a visible sinusoidal waveform or AC symbol, the two diodes are oriented with both cathodes pointing toward the common node that feeds the resistor–LED branch (the center-tapped full-wave arrangement), and the resistor and LED sit in series after the diode pair, with no ambiguity about which lead belongs to which component or which stage the LED occupies.

Scientific and Causal Correctness rubric:
level_1: The LED never turns on at any point in the video regardless of the AC source's state, or it flickers rapidly (faster than roughly five discernible on/off pulses per second, visible as a strobing glow) with no correlation to when the AC source is switched on: e.g., glowing before the source activates, staying dark after the source activates, or pulsing with no relationship to the source's on/off timing.
level_2: The LED does turn on only after the AC source is shown active, satisfying the basic on/off correlation that score 1 lacks, but once lit it shows a slow, clearly countable flicker (brightening and dimming through roughly one to five distinct pulses per second) instead of holding steady; this is a visibly slower, individually countable pulsing, unlike the rapid uncorrelated strobing described at score 1.
level_3: The LED lights up and stays steadily lit with no visible flicker once illuminated, but its timing relative to the AC source is wrong: it glows before the AC source's symbol or waveform turns on, stays lit after the source is shown switched off, or its onset lags the source's activation by a full extra beat with no rectifier-related cause shown on screen.
level_4: The LED illuminates at the same moment the AC source is activated and stays continuously lit for the rest of the video with no visible flicker, dimming, or pulsation; its emitted color stays one steady hue (red, yellow, or green, matching a standard indicator LED) rather than drifting toward white or blue.
level_5: The LED's glow onset coincides with the very first frame in which the AC source shows activation (waveform or power symbol turning on), and the LED then holds a constant, uniform brightness and color across its entire emitting surface for the rest of the video with no strobing, shimmer, or brightness modulation, visually indistinguishable from an LED driven by a steady DC supply.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal break; any one of the following is enough alone: (a) the breadboard, the AC source, a diode, the resistor, or the LED jumps to a visibly different location or orientation between two consecutive frames with no intermediate frame showing it in motion; (b) a diode body, resistor lead, or wire changes its physical shape into a different form (e.g., a straight lead becomes sharply kinked, or a diode's body outline changes) with no interpolating frames shown; (c) two components that should stay physically separate visibly overlap or pass through one another (e.g., the LED body appears to intersect the resistor); (d) the LED's glow goes from completely dark to fully lit, or the reverse, between two consecutive frames with literally no frame anywhere in the video showing a partial, in-between brightness; (e) the overall scene lighting shifts abruptly between bright and dark, with no lamp, light source, or camera movement shown to explain it.
level_2: Two or more of the following moderate problems occur together in the same clip (any single one of these appearing with none of the others present should instead be scored as 3): the resistor or a diode drifts to a slightly different spot or rotates a few degrees between shots with no camera movement to justify it; the LED's brightness rises from dark to fully lit over just two or three frames, faster than a smooth transition but still showing at least one intermediate partial-brightness frame, unlike the zero-frame flip described at score 1; the shadow cast by the LED or a diode swings to point in a visibly different direction even though neither the overhead light nor the camera has moved; or a wire or solder joint at one of the connection points blinks out of view for a frame or two and then reappears in the same spot.
level_3: Exactly one flaw is present: either a single item from the score-2 list occurring with none of that list's other problems present, or a distinct minor issue such as the LED's position jittering slightly (less than roughly one-tenth of its own height) across a few frames, one component being briefly hidden behind another for no clear reason and then reappearing in the same place, or the highlight on the resistor's surface shifting slightly in a way that doesn't match the rest of the scene's lighting.
level_4: The AC source, both diodes, the resistor, and the LED all keep fixed relative positions and orientations on the breadboard for the entire video; none of them jitters, warps, or changes shape; the highlight on the diodes' bodies and the shadow the LED casts on the breadboard point in the same direction and hold the same brightness for as long as the overhead lighting and camera stay put; every wire and lead stays visibly connected with no gaps opening or closing.
level_5: No spatiotemporal artifacts of any kind: every component's position, rotation, and size stay visually stable across the whole video, changing only if the camera itself moves; the specular highlight on the LED's lens and on the diodes' bodies shifts only when the light source or camera actually moves, and does so smoothly rather than jumping between frames; wires and leads keep a physically plausible, unchanging shape appropriate to their rigidity; no component visibly doubles, ghosts, or blurs into another between frames.