Ruhmkorff Induction Coil

This apparatus generates approximately 60 kV at the discharge terminals, sufficient to cause serious shock. Never touch the discharge terminals or secondary coil connections while energized. Keep all body parts and conductive materials at least 15 cm from the spark gap. The high voltage can also damage electronic devices and erase magnetic media nearby.

The high-voltage discharge produces ozone and nitrogen oxides. Use in well-ventilated areas and limit continuous operation to a few minutes. Extended exposure to ozone can cause respiratory irritation.

Purpose

Demonstrates how mechanical interruption of DC current produces high-voltage pulses through electromagnetic induction. Students see why transformers require changing current — steady DC produces no induced EMF — and observe the dramatic ~60 kV arc that results from rapid flux collapse in a high-turns-ratio coil.

Ruhmkorff induction coil on wooden base with large cylindrical secondary coil between black metal supports, mechanical vibrator assembly at right, discharge terminals on top showing small blue spark, and Xantrex DC power supply reading approximately 9.7 V and 0.8 A

Figure 1: The Ruhmkorff coil with iron-core secondary coil, mechanical vibrator interrupter, and discharge gap. A Xantrex DC power supply provides the low-voltage input.

Ruhmkorff Induction Coil

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Danger: High Voltage Hazard

Warning: Ozone Production

Purpose

Safety Warnings

Danger: High Voltage Hazard

Warning: Ozone Production

Purpose