A spark gap consists of two electrodes that are separated—usually by air—to allow a spark to form between them. Small spark gaps are used to ignite combustion in engines, and huge spark gaps are used in high-voltage switches at electrical substations. Spark gaps can also be used in novelty devices such as the “Jacob’s ladder,” in which electric arcs continuously stream upward between two wires. How are such toys dangerous to houseplants? Discuss