The thing about electricity is it only makes heat when there is a lot of resistance to its flow.Gene L said:
Take an electric heater for instance.
The heating element in one is made of materials that have a very high resistance to electricity passing thru it.
The wiring in your house that feeds the power to it is usually copper which has a very low resistance.
The low resistance wiring usually doesn't get even a little warm as it transmits the power to the heater.
Once in the heating element, its high resistance causes the electricity to create enough heat to cause the element to become red hot.
Carbon has very little resistance to electricity passing thru it.
With the high amount of charcoal (carbon) in black powder the low resistance allows the electricity to pass thru it with little heat produced.
Also, when electricity is forced to travel thru a pile of black powder, it moves to the outside of the pile rather than going thru it.
With the spark on just the surface of the powder, the small amount of heating that does happen rapidly cools off into the air around it.
Now, add to all of this, static electricity has a tremendous amount of voltage so it can jump relatively large distances but it has almost no amperage at all.
Amperage is the "Power" in electricity that does the work like heating.
Yes, lightning can cause fires but bear in mind, a lightning bolt has hundreds of millions of volts so the small percentage of amperage that's present still adds up to a lot of amperage and that can produce a lot of heat. Especially if it is trying to pass thru something with a lot of resistance, like the wood your house is built from or the trunk of a tree.
Ole Ben Franklin figured this out when he came up with the lightning rod.
By connecting it to the low resistance of the copper "grounding wire" the rod conducts the lightning bolt to the ground without hardly any heat being made.
Now, don't forget. There might be a pop quiz tomorrow in this physics class so read your assignment tonight. :rotf:
