Domain: Engineering — Electrical Engineering
Target concept: A lamp is powered by a battery, and when a second lamp is switched on, the first lamp becomes noticeably dimmer.

Video generation prompt: A battery supplies power to a single incandescent lamp; another identical incandescent lamp is connected in parallel through a switching switch, which can be turned on and off.

Evaluation guide:
(i) Target concept: Voltage sag due to battery internal resistance in parallel resistive loads.
Minimum mechanism: Battery must exhibit non-negligible internal resistance; lamps must be ohmic (incandescent) with positive temperature coefficient; parallel connection must be electrically valid (no series miswiring); switch must control only the second lamp"s path.
(ii)Storyline: Frame 1–3: First lamp lit, second lamp unlit, switch open, stable baseline. Frame 4–6: Switch actuation begins, visible mechanical motion. Frame 7–9: Switch fully closed, second lamp illuminates *and* first lamp dims *synchronously*, both remaining lit. Perspective: Fixed frontal view, full system in frame, no occlusion, consistent lighting. Visibility constraints: Filament glow must be resolvable; switch state (open/closed) must be legible; relative brightness difference between lamps must be discernible without measurement.

Manual:
Experimental Procedure
1. Show a battery powering a single incandescent lamp (lit).
2. Show a second identical incandescent lamp connected in parallel via a switch (open, lamp unlit).
3. Actuate the switch to close the circuit for the second lamp.
Observation of Experimental Phenomena
The first lamp remains lit but becomes visibly dimmer; the second lamp illuminates simultaneously.
Summary of Experimental Principles
When lamps are connected in parallel to a real battery (with internal resistance), adding a second lamp increases total current draw, causing greater voltage drop across the battery"s internal resistance — reducing terminal voltage and thus power delivered to each lamp.

Prompt Grounding rubric:
level_1: No battery visible, or fewer than two incandescent lamps present, or no switch present, or more than two lamps appear at any point, or the two lamps are clearly different in size/shape/appearance from each other.
level_2: Battery and one lamp are shown, but the second lamp is missing or impossible to tell apart from the first; or the switch is not wired into the second lamp's branch (e.g., it sits elsewhere, is disconnected, or is wired to the wrong component); or the two lamps are not connected in parallel (e.g., wired in series, or one lamp left dangling/unconnected).
level_3: Battery, two visually identical incandescent lamps, and a switch wired in series with only the second lamp's branch are all present and clearly connected in parallel across the battery terminals; both lamps and the switch stay within the same frame under a fixed camera viewpoint.
level_4: All conditions for score 3, AND the switch shows one clear, visible toggle action (or an unambiguous before/after open-vs-closed state change), AND both lamps and all wiring remain fully visible with no lamp or wire ever leaving the frame or being blocked from view for the entire clip.
level_5: All conditions for score 4, AND the switch is actuated exactly once during the clip, AND both lamps keep the same position, orientation, and spacing relative to each other and to the battery for the whole clip, AND no rendering glitch (flicker, doubling, or a lamp/wire momentarily disappearing) ever makes it unclear which lamp is which.

Scientific and Causal Correctness rubric:
level_1: Neither lamp's brightness visibly changes when the switch is actuated; or the first lamp gets brighter instead of dimmer; or the second lamp lights up while the first lamp's brightness stays exactly the same; or a lamp appears lit without any visible glowing filament.
level_2: The first lamp's brightness does change, but the second lamp never turns on at all; or the first lamp's brightness changes before the switch is actuated, or with no switch actuation shown at all.
level_3: Before the switch closes, the first lamp is lit and the second lamp is dark; the moment the switch closes, the second lamp turns on and the first lamp visibly loses brightness, while both lamps remain lit afterward (neither one goes fully dark).
level_4: All conditions for score 3, AND the first lamp's dimming is a smooth, one-directional decrease with no flicker or partial recovery, AND the second lamp's turn-on is a smooth, one-directional rise to steady brightness with no stutter or delayed flare-up. A mild shift toward a warmer, more amber tone in the first lamp as it dims is expected and should not count against the video: this matches how a real incandescent filament's color changes as it cools; only the smoothness of the brightness change should be judged here.
level_5: All conditions for score 4, AND the second lamp's turn-on and the first lamp's dimming both begin essentially the instant the switch closes, with no noticeable delay for either, AND the first lamp's brightness reduction is clearly and obviously lower than its starting level (not a marginal change) and stays dimmed for the rest of the clip. Any accompanying warm-toned color shift in the first lamp is consistent with real filament behavior and should be treated as a supporting cue, not a flaw.

Spatiotemporal Consistency rubric:
level_1: The battery, either lamp, or the switch jumps to a new position or vanishes and reappears between frames; a wire appears or disappears with no physical cause; the overall scene brightness jumps abruptly with no connection to either lamp's or the switch's state; the camera cuts or jumps to a different angle mid-clip.
level_2: One lamp or the battery drifts out of its starting position by more than about 10% of its height between the part of the clip before and after the switch closes; a wire connection visibly detaches and reattaches with nothing touching it; the background lighting flickers or changes tone independently of either lamp's own brightness.
level_3: The battery, both lamps, and all wiring stay in the same place and orientation for the entire clip; neither lamp nor the switch ever vanishes, duplicates, or teleports; the wiring stays intact and visibly connected throughout with no broken or floating segments.
level_4: All conditions for score 3, AND the switch's toggle motion is smooth and physically plausible, with visible motion between its open and closed states rather than an instant jump; AND the brightness changes in both lamps play out as smooth, continuous transitions rather than abrupt jumps from one frame to the next; AND the camera framing stays steady with no jitter, shear, or zoom drift.
level_5: All conditions for score 4, AND neither lamp's filament flickers, strobes, or visibly stutters in brightness at any point in the clip, AND no ghosting or doubling of the lamps, switch, or wiring ever appears, AND every object's outline (lamp bulbs, switch, wires) stays sharp and stable across the whole video with no shimmering or warping edges.