PlateChargeNode¶

Overview¶

Base class for representation of plate charge. Plate charge is represented as an integer number of '+' or '-' symbols. These symbols are distributed across some portion of the plate's top face.

All model coordinates are relative to the capacitor's local coordinate frame.

@author Chris Malley (PixelZoom, Inc.) @author Jesse Greenberg (PhET Interactive Simulations) @author Sam Reid (PhET Interactive Simulations) @author Andrew Adare (PhET Interactive Simulations)

Class PlateChargeNode¶

import { PlateChargeNode } from 'scenerystack/scenery-phet';

Constructor¶

new PlateChargeNode( capacitor, modelViewTransform, options )¶

Instance Methods¶

getGridSize( numberOfObjects, width, height )¶

@param {number} numberOfObjects @param {number} width @param {number} height @private

@returns {Dimension2}

getPlateCharge()¶

Get plate charge from capacitor in the model @public

@returns {number} charge

getContactXOrigin()¶

Gets the x offset (relative to the plate origin) of the portion of the plate that is facing the vacuum gap @public

@returns {number} offset

getContactWidth()¶

Gets the width of the portion of the plate that is in contact with air. @public

@returns {number}

isPositivelyCharged()¶

Returns true if plate is positively charged

@returns {Boolean} @public

paintCanvas( context )¶

Updates the view to match the model. Charges are arranged in a grid.

@param {CanvasRenderingContext2D} context @public

getNumberOfCharges( plateCharge, maxPlateCharge )¶

Computes number of charges, linearly proportional to plate charge. If plate charge is less than half of an electron charge, number of charges is zero. @public

@param {number} plateCharge @param {number} maxPlateCharge @returns {number}

Source Code¶

See the source for PlateChargeNode.js in the scenery-phet repository.