This device is designed specifically for physics laboratories in middle schools and universities, and can simultaneously complete two teaching tasks of "qualitative observation" and "quantitative verification" on one set of equipment, helping students intuitively understand Faraday's law of electromagnetic induction ε=- N ·ΔΦ/Δ t. Through this device, students can complete the complete exploration process from "phenomenon observation → variable control → data recording → law verification". Typical experiment: Connect a 300 turn coil to a galvanometer and record the zero point. Set the height of the photoelectric gate to h=20 cm, allowing the magnet to fall freely through the coil; Record the maximum deflection grid number n ₁ of the ammeter. Replace the 1000 turn coil and record n ₂. Calculate n ₂/n ₁ ≈ 1000/300 ≈ 3.3 and verify ε∝ N.