Polarization of light

Equipment

• Virtual polarizer–analyzer pair with field-vector display
• Slider “Góc phân tích θ” (analyzer angle)
• Slider “Cường độ ban đầu I₀” (initial intensity)
• “Đặt lại tham số” (reset) button; transmitted-intensity readout

Procedure

1. Scan the analyzer angle

   Drag the θ slider slowly from 0° to 180° and read the transmitted intensity. It is maximal at θ=0°, falls to zero at θ=90° (crossed polarizers) and recovers at 180° — the $\cos^2\theta$ signature of projecting the field onto the analyzer axis.

2. Test cos²θ quantitatively

   Set θ to 30°, 45° and 60° and record I at each. Compare the ratios $I/I_0$ with $\cos^2\theta$: expect 0.75, 0.50 and 0.25. The electric field is transmitted as $E\cos\theta$, so intensity, proportional to $E^2$, follows $\cos^2\theta$.

3. Scale the initial intensity

   Move the I₀ slider and confirm the cos² shape is preserved — only the scale changes. Then predict the reading for θ=0° and θ=90° at a new I₀ before measuring, and explain why a real polarizer also absorbs about half of unpolarized incident light.

Simulation

Experiment history

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