Energy Transducers

Photovoltaic cells turn light into electricity. Drag the lamp closer — light intensity rises with 1/d² (inverse-square law), raising the cell current and voltage. The 2 m² panel feeds a motor-driven fan — watch the Watt meter climb as you close the gap.

Two different metals joined at a junction generate a small voltage through the Seebeck effect — V = S · ΔT. Move the heat source closer to raise the temperature difference and the output voltage.

Piezoelectric crystals convert a change in stress into charge. Voltage appears only while the force is changing — press down or release to generate a spike, then hold still and the charge leaks away, dropping the voltage back to zero.

A moving magnet changes the magnetic flux through the coil, inducing a voltage (Faraday’s law). Drag the magnet through the coil tube — EMF appears only while it is moving — or flip Auto on and watch it oscillate through the tube to make a sine wave.

Spinning the magnet next to a single coil makes the magnetic flux linking the winding alternate, inducing an alternating EMF. Rotate the magnet by hand — EMF appears only while it turns — or flip Auto on to spin it slowly and trace a clean sine wave.

Zinc and copper plates react with acid, releasing electrons. Deeper immersion exposes more active plate area, cutting internal resistance so more current and power flow through the lamp.