Domain: Engineering — Energy Engineering
Target concept: When a temperature difference is formed, the LED is lit, and the greater the temperature difference, the higher the brightness.

Video generation prompt: Using a thermoelectric generator as a power source to form a closed loop with an LED lamp, then heating one end of the thermoelectric generator and cooling the other end, observe the on/off condition.

Evaluation guide:
(i) Target concept: Thermoelectric power generation via Seebeck effect requiring a sustained thermal gradient across dissimilar conductors.
Minimum mechanism: Two physically distinct thermal reservoirs (hot and cold) must simultaneously contact opposite faces of the TEG; electrical load (LED) must be directly connected in series with no intervening regulation; LED must be forward-biased and rated for low-voltage DC output.
(ii)Storyline: Frame 1–2: Static shot of TEG and LED with wires disconnected. Frame 3–4: Wires connected between TEG terminals and LED leads. Frame 5–6: Heating source placed firmly on left TEG face. Frame 7–8: Cooling source placed firmly on right TEG face. Frame 9–10: LED illuminates (and remains illuminated) only from this point onward while both sources stay in contact. Perspective: Fixed frontal close-up capturing TEG center, both thermal interfaces, and LED within same plane; no occlusion of critical junctions; lighting ensures LED on/off state is unambiguously legible.

Manual:
Experimental Procedure
1. Place thermoelectric generator (TEG) centrally.
2. Connect LED lamp to TEG terminals with wires to form closed loop.
3. Apply heating source to one end of TEG and cooling source to opposite end.
Observation of Experimental Phenomena
LED turns ON only after both thermal sources are applied to opposite ends of TEG; brightness remains stable while thermal gradient is maintained.
Summary of Experimental Principles
When a temperature difference is formed across the TEG, it generates voltage; greater temperature difference produces higher voltage, increasing LED brightness.

Prompt Grounding rubric:
level_1: Neither the thermoelectric generator (TEG) nor the LED lamp appears in frame; no heating source (e.g., flame or hot plate) or cooling source (e.g., ice pack or cold metal block) is shown; the TEG and LED are never wired into a closed circuit; no setup or activation sequence is shown at all.
level_2: The TEG and LED both appear but are not wired into a closed loop, or only one thermal source (heating or cooling, not both) is shown, or the TEG and LED are wired together but neither thermal source is ever applied, or the LED sits loose on the TEG's surface instead of being wired to its terminals.
level_3: The TEG and LED are wired together into a visible closed loop; both a heating source and a cooling source are present and placed on opposite sides of the TEG; every required object (TEG, LED, wires, heat source, cold source) is shown, correctly shaped and identifiable; the thermal sources are placed onto the TEG only after the wiring is already in place.
level_4: Everything required for score 3 is present. In addition, the heating source and cooling source sit on genuinely opposite faces of the TEG (not the same face, and not overlapping each other); the wires run directly from the TEG's terminals to the LED's leads with no resistor, switch, or other component in between, and each wire connects to a visibly distinct terminal on both the TEG and the LED (no wire looping back to the same terminal or leaving a lead unconnected); no extra props clutter or obscure the core setup.
level_5: Everything required for score 4 is present. In addition, the TEG's two faces are clearly distinguishable as the hot side and the cold side by which thermal source touches each; the wiring is taut and fully traceable with no slack or tangled loops hiding the terminals; the heat source, TEG, cold source, and LED are all kept in one fixed left-to-right line, visible together in a single continuous shot with no repositioning or cutaway hiding any step.

Scientific and Causal Correctness rubric:
level_1: The LED never lights up at any point in the video; or it lights up before either thermal source touches the TEG; or its brightness changes with no corresponding change in the heating or cooling being applied; or it lights up while only one of the two thermal sources (just the hot side or just the cold side) is in contact.
level_2: The LED lights up, but the thermal sources are wrong for the effect - e.g., two heat sources or two cold sources are used instead of one of each, or both sources touch the same side of the TEG; or the brightness relationship runs backwards, dimming instead of brightening as the temperature difference grows.
level_3: The LED starts dark, then turns on only once both the heating source and the cooling source are touching opposite ends of the TEG; once lit, its brightness holds steady rather than flickering or pulsing; at no point does the LED light up before both thermal sources make contact.
level_4: Building on the 3-point description above, the LED stays lit for as long as both thermal sources remain in contact with the TEG; if either source is lifted away, the LED goes dark within the same shot; brightness never rises or falls without a matching change in whether or where the thermal sources are touching the TEG.
level_5: Building on the 4-point description above, the LED is dark in every frame where a thermal source is missing, only partly touching, or touching the wrong face, with no exception; brightness stays visually even across every lit frame, with no flicker or dimming that isn't explained by a thermal source being adjusted or removed.

Spatiotemporal Consistency rubric:
level_1: The TEG or LED jumps to a different position between frames, or the LED appears or disappears without a hand moving it; the overall lighting on the scene switches from bright to dark instantly with no fade or transition; the TEG or LED visibly warps, fractures, or changes shape; a camera cut or zoom breaks the single continuous view of the setup.
level_2: The TEG or LED wobbles or jitters without any structural break; the wire-to-TEG junction or a thermal source's contact with the TEG is hidden from view for a stretch of the video; the overall brightness on the scene shifts noticeably partway through without a full blackout; the shadow cast by the heat or cold source points in a different direction than the source's own position would produce.
level_3: The TEG, LED, wires, and thermal sources stay in the same relative arrangement for the whole video, with no part jumping position or changing shape; the scene's brightness and the direction of the shadows cast by the heat and cold sources stay matched to where those sources actually sit; the wire connections and the points where the thermal sources touch the TEG stay visible and unbroken throughout; the camera holds one fixed framing of the full setup with no cuts, pans, or zooms.
level_4: Building on the 3-point description above, the wire-to-TEG terminal junction and each thermal source's contact face stay fully visible and unobstructed for the entire time contact is maintained; no frame shows a thermal source only half-touching the TEG (e.g., lifted at one edge) during what should be steady contact; any hand motion placing a thermal source moves smoothly and realistically, with no floating or sudden repositioning.
level_5: Building on the 4-point description above, the TEG stays centered between the heat and cold sources for the whole video; the LED stays wired in and visible in frame throughout; none of the contact points ever show slippage or gaps; hand motion bringing a thermal source into place follows a natural approach with smooth acceleration and deceleration, never teleporting into position; no stray reflection or glare ever obscures whether the LED is lit.