Domain: Engineering — Electrical Engineering
Target concept: Three small light bulbs are connected in series. Adding an additional bulb will cause all the bulbs to become dimmer.

Video generation prompt: On the desk, three bulbs are connected in series with the battery and emit steady light; by briefly opening and reconnecting the circuit, a fourth bulb is inserted into the same series loop.

Evaluation guide:
(i) Target concept: Current reduction in a fixed-voltage series circuit due to increased total resistance.
Minimum mechanism: Battery provides approximately constant voltage; bulb filaments behave as ohmic resistors; circuit remains purely series (no parallel paths or additional voltage sources); bulbs are identical and operate within normal incandescent range (no burnout or nonlinear effects).
(ii)Storyline: Frame 0–3s: Stable wide shot, three bulbs + battery connected in visible linear series, all glowing steadily. Frame 3–4s: Close-up on one wire junction, wires separate smoothly, gap widens, all bulbs extinguish simultaneously. Frame 4–5s: Fourth bulb enters frame moving linearly into gap; terminals align with wire ends. Frame 5–6s: Wires reconnect onto fourth bulb terminals; loop closes completely. Frame 6–10s: All four bulbs glow steadily, uniformly dimmer than initial state; no brightness fluctuation, no bulb off, no new light sources. Perspective: Fixed overhead or eye-level desk view; no cuts; all objects remain in-frame and fully visible; no occlusion of critical junctions or filaments.

Manual:
Experimental Procedure
1. Place battery and three identical incandescent bulbs on desk; connect them end-to-end in a single unbranched loop using insulated wires.
2. Power on: all three bulbs emit steady, equal brightness.
3. Briefly disconnect one wire joint to open the circuit (all bulbs extinguish).
4. Insert a fourth identical bulb into the break, then reconnect the wires to include it in the same series loop.
Observation of Experimental Phenomena
After reconnection, all four bulbs glow continuously but are uniformly dimmer than the original three-bulb state.
Summary of Experimental Principles
In a series circuit powered by a fixed-voltage source, total resistance increases with each added resistor (bulb filament); current decreases per Ohm’s Law (I = V/R); since bulb brightness depends on current, all bulbs become dimmer.

Prompt Grounding rubric:
level_1: Desk shows no fixed-voltage circuit at all: three bulbs, the battery, or the connecting wires are missing; the fourth bulb never appears; and no wire-junction is ever opened or reconnected on screen.
level_2: Three bulbs and the battery are on the desk, but they are not clearly wired into one continuous loop (e.g., a wire trails off unconnected); or the moment a wire junction is opened and reclosed is skipped or hidden (a hand or a cut hides the whole gap); or the fourth bulb shows up in the scene without ever being placed into the loop's break.
level_3: Three bulbs and the battery are visibly wired into a single unbranched loop; a gap opens at one wire junction and is later closed; the fourth bulb sits in that gap, occupying a slot in the loop, but at least one of its two terminals is never clearly shown touching a wire end (e.g., the camera angle or a hand hides one contact point), so full electrical continuity is not confirmed by sight.
level_4: Three bulbs and the battery are visibly wired into a single unbranched loop; the junction is held open long enough to see the gap, then reclosed; both terminals of the fourth bulb are clearly shown meeting the two wire ends that had separated, producing one unbroken loop containing all four bulbs with no parallel branch, no second battery, and no wire bypassing the new bulb.
level_5: All elements of score 4 are met, and in addition: the desk, the battery, and the three original bulbs stay in the same positions and orientations they had before the break; the shot has no cut or camera move; and the fourth bulb may be spliced in at whichever single junction is shown (next to the battery or between any two bulbs), since any such location keeps the same series topology and is equally acceptable for full credit.

Scientific and Causal Correctness rubric:
level_1: No bulb ever lights up; or all bulbs stay exactly as bright after the fourth bulb joins the loop as they were with only three; or the fourth bulb burns bright while the original three go dark; or brightness jumps around inconsistently (e.g., a bulb suddenly flares brighter right after the fourth bulb is added).
level_2: The three original bulbs glow steadily before insertion, but afterward the pattern breaks series logic: only one of the four bulbs visibly dims while the others hold their original brightness; or the dimming starts before the fourth bulb's terminals are actually connected; or the fourth bulb lights while one or more of the original three stays completely dark.
level_3: Three bulbs glow steadily before insertion; once the fourth bulb is wired into the loop, all four bulbs are lit and every one looks dimmer than the original three, but the amount of dimming looks noticeably uneven across the four filaments (e.g., one still looks nearly as bright as before while the others look much dimmer).
level_4: Same starting and ending state as score 3, but the dimming looks even: all four bulbs settle at a similarly reduced brightness compared with the original three, none of the four keeps its original brightness, and none of the four outshines the other three once the loop is closed.
level_5: All elements of score 4 are satisfied, and the timing matches the physics: the dimming appears only once the wires are fully reconnected to the fourth bulb (no bulb dims or brightens while the circuit is still open); no bulb flickers, flares, or briefly regains its original brightness afterward; and the four-bulb reduced brightness holds steady for the rest of the clip, consistent with one fixed-voltage source driving a larger total filament resistance.

Spatiotemporal Consistency rubric:
level_1: A bulb, the battery, or a wire jumps to a new spot on the desk with no visible travel getting there; a wire end vanishes from one point and reappears already fused at another point; the fourth bulb pops into frame already sitting inside the closed loop instead of moving into the gap; a bulb's glowing filament disappears and reappears with no dimming or reconnection event to explain it; the camera cuts or jumps to a different angle mid-action; or the room lighting abruptly shifts brightness or the desk shadows flip direction with no cause.
level_2: Circuit opening shows no motion of wires: gap appears instantly without separation movement; reconnection shows no contact motion: wires fuse without approach; fourth bulb appears without translational motion into frame; bulb brightness changes occur without temporal continuity (e.g., instant on/off without fade or stabilization).
level_3: Wires separate and reconnect with visible motion; fourth bulb moves into position along a continuous trajectory; all bulbs maintain consistent size, shape, and orientation; lighting and shadows remain stable across sequence; however, minor visual artifacts exist: e.g., brief occlusion hides critical contact moment, or one bulb's filament is momentarily not visible due to glare.
level_4: All motions are smooth and physically plausible: wire ends move apart linearly, pause, then move together linearly; fourth bulb translates steadily into loop without rotation or scaling anomaly; all bulbs remain fully visible throughout: no occlusion of terminals, filaments, or wire-bulb junctions; no lighting/shadow discontinuities; no structural warping or stretching of wires/bulbs.
level_5: All elements of score 4 are satisfied AND temporal pacing is perceptually coherent: circuit opening duration is visibly distinct from reconnection duration; insertion motion begins only after opening is complete and ends only upon full terminal contact; brightness transitions occur strictly after mechanical completion: no overlap between motion and luminance change; inter-frame motion is fluid with no strobing, jitter, or ghosting.