ConductivityTesterNode

ConductivityTesterNode (from scenerystack/scenery-phet) draws a light bulb connected by wires to a battery and two draggable probes (a red "+" and a black "−"). When both probes are immersed in a conductive solution, the model sets brightnessProperty above zero and the bulb glows — the classic "does this liquid conduct electricity" apparatus used in chemistry sims like Acid-Base Solutions. It reuses ProbeNode-style probe graphics and WireNode-style cubic-bezier wires internally (as private helper classes local to this file, not the standalone exported ProbeNode/WireNode).

import { ConductivityTesterNode } from 'scenerystack/scenery-phet';
import { NumberProperty, Property } from 'scenerystack/axon';
import { Vector2 } from 'scenerystack/dot';

A minimal example

const brightnessProperty = new NumberProperty( 0, { range: { min: 0, max: 1 } } );
const positionProperty = new Property( new Vector2( 0, 0 ) );
const positiveProbePositionProperty = new Property( new Vector2( -0.5, -1 ) );
const negativeProbePositionProperty = new Property( new Vector2( 0.5, -1 ) );

const conductivityTesterNode = new ConductivityTesterNode(
  brightnessProperty,
  positionProperty,
  positiveProbePositionProperty,
  negativeProbePositionProperty,
  { tandem: tandem.createTandem( 'conductivityTesterNode' ) }
);

Constructor

new ConductivityTesterNode(
  brightnessProperty: TReadOnlyProperty<number>,
  positionProperty: TProperty<Vector2>,
  positiveProbePositionProperty: TProperty<Vector2>,
  negativeProbePositionProperty: TProperty<Vector2>,
  providedOptions: ConductivityTesterNodeOptions // tandem is required
)

All four positions are in the model coordinate frame; positionProperty is the bottom-center of the bulb, and moving it translates both probes with it (their relative offset is preserved).

Options

Option	Default	Effect
modelViewTransform	identity	Projects all four model positions into view coordinates
probeSize	Dimension2(20, 68)	Shared dimensions for both probe plates
probeDragYRange	null	If set, constrains how far probes can be dragged vertically relative to positionProperty, in view coordinates; null means unconstrained
positiveProbeFill / negativeProbeFill	'red' / 'black'	Probe plate colors
bulbToBatteryWireLength	40	View-coordinate length of the wire between bulb and battery
keyboardDragListenerOptions	—	Forwarded to the shared KeyboardDragListener that moves both probes together

Instance API

Member	Effect
shortCircuit (getter/setter)	Shows/hides a "Short Circuit" label above the bulb; it's the caller's responsibility to also set brightnessProperty appropriately when toggling this

The two probes always drag together, vertically only

ConductivityTesterNode wires one DragListener to both probes (positiveProbe and negativeProbe share probeDragListener/probeKeyboardDragListener), and that listener only ever changes their shared y-coordinate — there's no way to drag the probes independently or horizontally with the built-in listeners. If your sim needs independently movable probes, you'll need to compose your own probe graphics rather than repurposing this Node's drag behavior.