Domain: Engineering — Electrical Engineering
Target concept: An RC circuit charges the capacitor, driving the LED brightness.

Video generation prompt: On the workbench, there is a simple RC charging circuit: a battery, switch, and resistor are connected in series to charge a capacitor, and an LED is connected in parallel across the capacitor's two terminals; one hand toggles the switch to connect the battery.

Evaluation guide:
(i) Target concept: Charging an RC circuit causes capacitor voltage to rise toward the battery voltage; because the LED is wired in parallel with the capacitor, its terminal voltage rises together with the capacitor, producing an observable increase in LED brightness as the capacitor charges.
Minimum mechanism: Battery, switch, and resistor must form a closed series charging path into the capacitor; capacitor must be shown charging from the battery through the resistor; LED must be connected across the capacitor's two terminals (a parallel branch alongside the capacitor, not simply chained end-to-end in the same single loop as the resistor); LED must be forward-biased so it can conduct once capacitor voltage exceeds its forward threshold; brightness must track capacitor voltage, increasing as the capacitor charges and leveling off as the capacitor approaches full charge.
(ii) Storyline: Frame 0–2s: Static wide shot: battery, switch, resistor, capacitor, and LED all laid out on the workbench with the LED visibly bridging the capacitor's two terminals; switch open; LED unlit. Frame 2–3s: Hand enters from bottom edge, approaches switch. Frame 3–4s: Hand contacts and toggles switch from open to closed (visible mechanical motion). Frame 4–9s: LED brightness increases from off through dim and medium toward bright, rising quickly at first and gradually slowing as it nears its peak, with no reversal; all components remain spatially fixed. Frame 9–10s: LED holds at its stable maximum brightness; hand fully withdrawn; no secondary events. Perspective: Fixed frontal or 30° angled view, full circuit always in frame, no occlusion of LED, capacitor, or switch during the transition.

Manual:
Experimental Procedure
1. Place battery, switch, and resistor in series on the workbench, forming a charging path into the capacitor; connect the LED in parallel across the capacitor's two terminals.
2. Connect the components with wires so that closing the switch completes the battery-resistor-capacitor charging loop, with the LED bridging the capacitor.
3. With switch open, observe LED is off (capacitor uncharged, zero voltage across it).
4. Toggle switch to closed position with hand.
Observation of Experimental Phenomena
LED begins unlit → gradually increases in brightness as the capacitor charges → stabilizes at a steady glow once the capacitor approaches full charge; brightness rise is smooth and non-instantaneous, slowing as it approaches its peak.
Summary of Experimental Principles
An RC circuit charges the capacitor: when the switch closes, capacitor voltage rises exponentially toward the battery voltage as current flows in through the resistor, with the resistor limiting the initial charging current. Because the LED is wired in parallel with the capacitor, the LED's terminal voltage rises together with the capacitor's voltage; once this voltage exceeds the LED's forward threshold, the LED conducts and its brightness increases smoothly as the capacitor continues to charge, leveling off as the capacitor approaches full charge and its voltage (and hence LED brightness) stabilizes.

Prompt Grounding rubric:
level_1: Fewer than all five core parts (battery, switch, resistor, capacitor, LED) can be identified together in a single coherent circuit layout on the workbench, or the workbench itself is not shown.
level_2: All five parts can be identified but the wiring is wrong for this circuit: for example the LED is chained into the same single loop as the battery, switch, and resistor as though it were an ordinary series bulb, with no separate branch bridging the capacitor's own two terminals; or a component is swapped for something unrelated (e.g., a light bulb in place of the LED, a wire coil in place of the resistor).
level_3: Battery, switch, and resistor are connected in series into the capacitor, and the LED is connected across the capacitor's own two terminals (a visible branch alongside the capacitor rather than simply chained into the main loop); a hand enters frame and touches the switch, but the switch stays in the open position for the entire clip.
level_4: The battery-switch-resistor path into the capacitor and the LED's parallel connection across the capacitor are both correctly shown; a hand enters frame and visibly toggles the switch from open to closed (e.g., a lever moves or contacts meet), but the LED shows no brightness change at any point.
level_5: The battery-switch-resistor charging path and the LED's parallel connection across the capacitor are both correctly shown; the hand visibly toggles the switch from open to closed; the LED is dark before the toggle and visibly lit for at least one full second after it, with no extra components added, no component duplicated, and no LED shown with reversed leads/orientation relative to the capacitor terminals it bridges.

Scientific and Causal Correctness rubric:
level_1: LED is already lit before the switch is closed, or never lights up at all after the switch closes, or jumps from fully dark to fully bright within essentially a single instant with no visible ramp, or blinks on and off repeatedly rather than tracing one continuous rise, or its color shifts away from a single steady hue partway through the charging interval.
level_2: LED switches on at full brightness immediately after the toggle with no perceptible ramp; or the capacitor is missing or is drawn as a different part (e.g., a second battery or a coil); or the resistor is missing or replaced by a bare wire; or the LED is shown wired only into the battery-switch-resistor loop with no visible bridge across the capacitor's terminals, so its brightness cannot plausibly be tracking capacitor voltage.
level_3: LED stays dark until the toggle, then visibly brightens over time instead of snapping on, and is shown bridging the capacitor's two terminals as required; but the brightening either reaches its full level almost immediately (within roughly half a second of the toggle) or never settles at a stable bright level anywhere within the ten-second clip, so the ramp duration doesn't read as a charging capacitor.
level_4: LED stays dark until the toggle, then brightens smoothly and continuously from off to a clearly bright, stable level with no flicker, dimming, or reversal partway through; the brightening rises monotonically across the interval with no stepwise jumps or plateaus; the final brightness holds for at least a short stretch before the clip ends.
level_5: In addition to the 4-point requirements, the climb visibly decelerates (rising quickly right after the toggle and progressively slowing as it nears its peak, matching the shape of a capacitor charging toward a fixed voltage), settles at a clearly bright peak, and holds that peak steadily for a sustained stretch of the remaining clip (roughly the last several seconds) with no later dimming, flicker, or color shift, and with no glow or swelling shown coming from the resistor or capacitor itself.

Spatiotemporal Consistency rubric:
level_1: The LED or capacitor jumps to a new position between frames (e.g., appears mid-air then snaps onto the board), the switch resets to its open position after the hand lets go, the LED's brightness changes abruptly between one frame and the next with no visible transition, the workbench and its components change size or vanish partway through the clip, or the scene lighting or shadows shift abruptly between bright and dark with no lamp or camera movement to explain it.
level_2: The hand loses contact with the switch before finishing the toggle motion, the LED or capacitor shifts to a different spot on the board between the pre-toggle and post-toggle shots, the resistor or capacitor appears rotated by more than roughly 30 degrees without any hand touching it, a labeled part (e.g., a printed component label) blinks in and out of view, or a component's cast shadow vanishes and reappears pointing in a different direction between frames.
level_3: The hand keeps continuous contact with the switch through the whole toggle motion, and the battery, switch, resistor, capacitor, and LED all stay in the same relative positions and orientations throughout; however the hand's motion has at least one noticeable jump in speed (e.g., it suddenly speeds up or stalls), or the LED's brightening shows at least one visible backward flicker (a moment where it dims before continuing to brighten).
level_4: The hand's motion from approach through contact, toggle, and withdrawal reads as one continuous, evenly-paced motion; every component stays rigidly in place with no drift in position or angle; the LED's brightening rises without ever visibly dimming partway through; the camera view does not pan, tilt, or zoom, and no part of the circuit appears to shift relative to another as it would if the camera had moved.
level_5: All of the level-4 conditions hold, and in addition: the hand's approach, toggle, and withdrawal show no sudden speed changes anywhere in the motion; the LED's brightening traces a single unbroken curve from dark to peak with no visible pause, stutter, or reversal at any point; and the relative spacing between the battery, switch, resistor, capacitor, and LED looks identical in the first and last frames of the clip, with the camera framing unchanged throughout.