• Drag charges: Move the red and blue source charges along the horizontal axis.
• Position test charge: Click and drag the green/orange test charge anywhere.
• Set initial velocity: Hold Shift, click the test charge, drag to draw a velocity vector and release to set initial velocity.
• Adjust magnitudes: Use sliders to change charge strengths.
• Run simulation: Click Play to see the test charge move along the electric field.
• Pan canvas: Click and drag anywhere on empty space to move the view.