Domain: Engineering — Electrical Engineering
Target concept: RC low-pass circuit driven by frequency sweep, input/output LED amplitude indication

Video generation prompt: A RC low-pass circuit driven by a frequency-sweeping sinusoidal signal from low to high, with a red LED at the input and a blue LED blinking at the output.

Evaluation guide:
(i) Target concept: Frequency-dependent attenuation in a passive RC low-pass filter manifested as a decreasing conduction duty cycle in a diode-driven LED at the output node.
Minimum mechanism: Input sinusoid must drive the RC network; capacitor voltage lags and diminishes with rising frequency; the blue output LED only lights when its anode-cathode voltage exceeds its forward threshold (~3V, notably higher than a red LED's ~1.8-2V), so as the swept frequency rises and the attenuated output's peak voltage falls below that threshold, the blue LED's on-time shrinks toward fully off; the red LED is driven directly from the unfiltered input and is therefore unaffected by the sweep.
(ii)Storyline: Frame 1-2: Red LED fully lit; blue LED is lit almost continuously with only brief flickers off, reflecting the largely unattenuated output at the lowest swept frequency. Frame 3-5: Red LED remains steady; blue LED's on-intervals shorten and its off-intervals lengthen as the sweep climbs through the low-mid range. Frame 6-8: Blue LED's off periods dominate, with only brief flashes remaining as the frequency continues to climb. Frame 9-10: Blue LED stays fully off as the sweep reaches its highest frequencies; red LED unchanged throughout. All events occur in fixed frontal view; no camera movement; no occlusion; input and output LEDs remain simultaneously visible and spatially registered to circuit nodes throughout.

Manual:
Experimental Procedure
1. Connect signal generator to RC circuit input.
2. Place red LED at input node (across generator output).
3. Place blue LED at output node (across capacitor).
4. Sweep input frequency from low to high.
Observation of Experimental Phenomena
- Red LED remains continuously lit.
- Blue LED blinks, with blink rate decreasing as frequency increases.
- At high frequencies, blue LED stops blinking entirely (off state).
Summary of Experimental Principles
- RC low-pass filter attenuates high-frequency signals.
- Output voltage across capacitor decreases as frequency rises.
- Blue LED only conducts when output voltage exceeds forward threshold — occurs less frequently at higher frequencies.

Prompt Grounding rubric:
level_1: No RC network is visible (no resistor/capacitor pairing anywhere in the shot); no red LED anywhere near an input node; no blue LED anywhere near an output node; nothing in the frame suggests a frequency sweep is happening (no signal generator, no frequency readout, no sweeping waveform on a display); the red LED, blue LED, and circuit are not shown together in one coherent shot.
level_2: At least one LED (red or blue) is visible, but the colors are swapped relative to their roles (e.g., blue at the input, red at the output); the RC network is only partly shown, missing either the resistor or the capacitor; nothing signals the driving frequency is changing over time (no dial turning, no readout updating, no waveform sweep); the red LED, blue LED, and circuit appear in separate shots rather than one continuous frame.
level_3: A red LED sits at the circuit's input node and a blue LED sits at its output node; the RC low-pass network is recognizable, with a resistor and a capacitor both visible in series; something in the frame signals a frequency sweep is underway: a labeled signal generator with a changing frequency readout, or an animated sine wave sweeping across a display; the red LED, blue LED, and RC network all appear together in one fixed shot.
level_4: Everything required for a 3 also holds, and additionally: the red LED stays lit for the whole clip without going dark; the blue LED visibly switches on and off at least a few times over the course of the clip; the RC network's wiring matches a standard low-pass layout (signal in, through the resistor, then the capacitor to ground, with the output taken across the capacitor); the camera never cuts away from or repositions relative to the two LEDs.
level_5: Everything required for a 4 also holds, and additionally: the red LED's color looks like a clean, steady red with no flicker or tint shift, and the blue LED's color looks like a clean, steady blue with no flicker or tint shift; both LEDs look like the same type of component, matching in size and shape; the frequency sweep is clearly indicated by an on-screen label or readout whose value visibly changes over a modest range a viewer could plausibly track by eye, for example, sweeping from under 1 Hz up to roughly 10-15 Hz, rather than into the kHz range where individual blinks would no longer be distinguishable; the circuit's wiring is easy to trace with no hidden connections; the whole shot stays fixed with no camera motion or zoom.

Scientific and Causal Correctness rubric:
level_1: The blue LED stays lit continuously regardless of the sweep, or blinks at the same steady rate throughout with no visible change as the frequency changes; the red LED itself blinks or dims at high frequency (it should stay steady, since it is driven directly and isn't filtered); the output LED glows a color other than blue; there is no visible difference in behavior between the 'input' and 'output' indicators at all.
level_2: Both LEDs blink in sync with each other, or the blue LED's brightness and blink pattern look just like the red LED's; the blue LED's blink rate looks the same near the start of the sweep as near the end, with no visible slowing; the circuit is wired backwards for a low-pass filter (for instance, the capacitor sits at the input and the resistor at the output, or the two are in parallel rather than in series); the output is taken across the resistor instead of the capacitor.
level_3: The red LED stays continuously lit throughout, serving as a steady indicator that the input signal is present; the blue LED clearly blinks in discrete on/off pulses; watching from the start of the clip to the end, the blue LED's blinking visibly slows down as the sweep progresses, with longer gaps between flashes later in the clip than earlier; the circuit shows the resistor in series between the source and the output node, with the capacitor from that node to ground.
level_4: Everything required for a 3 also holds, and additionally: the red LED's brightness looks rock steady with no dimming or flicker of its own; the blue LED looks like a clean on/off switch rather than gradually dimming or fading between states; the gaps between blue LED flashes keep growing later in the clip rather than staying flat or shrinking; the blue LED never lights up brightly right when the red LED is dark, which would break the expected pattern where the input is always active.
level_5: Everything required for a 4 also holds, and additionally: the blue LED is lit almost continuously, with only very short off-gaps, near the very start of the sweep when the frequency is lowest and the filtered signal is least attenuated; as the sweep proceeds, the blue LED's on-time visibly shrinks and its off-time visibly grows, until by the later part of the clip it stays off entirely; there is no point where the blue LED suddenly lights up brightly again after it has already gone quiet for a stretch; the whole pattern reads as one smooth, one-directional slowdown from near-continuous blinking to fully off.

Spatiotemporal Consistency rubric:
level_1: The red LED, blue LED, or RC components jump to a different position, or vanish and reappear, between adjacent frames rather than moving continuously; the scene goes to black and then flashes back on rather than changing gradually; the circuit's scale or orientation suddenly jumps; the blue LED is shown reacting before the red LED, i.e., the output changes before the input is even established.
level_2: One of the two LEDs goes dark for a noticeable stretch and then comes back with no visible cause; a component label or value jumps to a new position without any visible motion getting it there; the background (e.g., the workbench) swaps abruptly partway through the clip; the red and blue LEDs look like they are lit under different lighting within the same frame: for instance, one looks shadowed while the other looks brightly spotlit.
level_3: The RC circuit, the red LED, the blue LED, and the signal source (if shown) all stay visible and keep the same positions relative to one another throughout; nothing in the shot gets clipped or blocked from view partway through; the lighting on the whole setup looks like the same source and direction the entire time, rather than swapping sides or suddenly brightening or dimming; the circuit's proportions look normal, without warping or shearing; the footage plays smoothly without stutters or dropped motion.
level_4: Everything required for a 3 also holds, and additionally: the red LED keeps the same size, position, and orientation across the clip; the blue LED keeps the same size, position, and orientation relative to the red LED; the circuit's traces and leads don't stretch, warp, or morph between frames; if a frequency readout or waveform display is shown, its numbers or trace update smoothly rather than jumping or glitching.
level_5: Everything required for a 4 also holds, and additionally: the LEDs' on/off switching looks like a clean, near-instant change rather than a slow fade or ramp up/down in brightness; the component leads and PCB traces look sharp and steady rather than flickering or shifting in ways the LED behavior doesn't explain; the foreground (LEDs, circuit) and background (bench, backdrop) move together with no visible sliding or misalignment between them; nothing about the framing looks digitally re-scaled or repositioned mid-clip; the solder joints and wiring keep a consistent, sharp look throughout.