MIT Physics Demo -- Jacob's Ladder and the Melting Nail

A solenoid is connected to AC power. First, a 10,000-turn coil is placed over the solenoid, but is not connected to the power source. However, the solenoid still induces current in coil, creating very high voltages because of the high number of turns. The rabbit ear spark gap creates an arc that moves from the bottom of the gap to the top (an effect known as Jacob's Ladder). This is due to convection and will not work upside-down

Next, a 1-turn copper loop (containing a gap filled by a nail) is placed over the solenoid. This time the induced current is very large, rather than the voltage. This high current encounters strong resistance in the nail creating temperatures so hot that the nail is melted.

See the original posting on MIT TechTV - http://techtv.mit.edu/videos/726

Category:

Education

Tags:

• mit
• mittechtv
• physics
• demonstration
• demo
• solenoid
• inductor
• coil
• turn
• melt
• melting
• nail
• jacob
• ladder
• voltage
• current

[colt4667]

poor nail went to the electric chair.

[DanThePropMan]

Anyone else think "Jacob's Ladder and the Melting Nail" would make a great name for a band?

[JkAc9597]

@inanevenator I dare you to find out

[inanevenator]

What happens if you touch it?

[gennaman2bit]

@johnyz656 Wrong, the lines of flux DO enter in the secondary coil, and this links primary and secondary together. In 1st case we have a secondary with many many more loops than the primary. This produces high voltages but low currents. In 2'nd case we have 1 only loop. This produces high current with low voltage. In both case voltage x current = wattage is almost the same (true if in 1st case we short circuit the secondary output)

[gennaman2bit]

@RockGodZeppelin it sounds like a 60Hz

[bhemophilus]

extreme current inducing the melting. 

[bhemophilus]

extreme current inducing the melting.

[bhemophilus]

extreme current inducing the melting

[johnyz656]

hey great post! how does that work. I mean the flux is in the core and does not enter the unconnected secondary right? So I understand how the lines of flux enter the core but I am amazed that electricty is being produced in the secondary when the lines of flux remain in the iron core.....got any advice? thanks

[MrAnuarsh]

Great!