Movement of tiny bits of ice and water droplets inside a thunderstorm causes electrical charge to build up in different parts of the cloud. The charge build-up can be negative in some parts and positive in other parts. These opposite charges are attracted to one another. When the attraction between the positive and negative charges grows strong enough, the charges travel through the air as lightning.
While most lightning happens within the clouds, some of the time electric charge also builds up in the ground below the cloud and so the charges travel through the air between the cloud and the ground.
As electricity travels through the air, it makes the air heat up and expand very quickly. This makes a shockwave that we hear as thunder.
How does the Tesla coil make lightning?
The Tesla coil is plugged in and gets its power from a power station (like the appliances in your house). It contains electrical transformers (which increase the voltage to between 2 and 2.8 million volts). This electricity runs around the flat coil at the bottom, which magnetically charges the tall upright coil. When the tall coil builds up enough electricity, it escapes from the top of the coil, down to the ground, taking the easiest path it can.
The main difference is that naturally-occurring lightning is static electricity and is very powerful, but does not last very long, while the tesla coil uses current electricity and runs for a long time, but is much less powerful than lightning. This means Tesla coils can’t be used to test how much damage would be done to objects in a lightning strike, but can help determine which objects are more likely to be hit by lightning.
Rubber is a good at protecting against weak sources of electricity, but not powerful ones like lightning.
Electricity always travels along the easiest path. We call the easy paths for electricity good conductors of electricity. Rubber is a good insulator, which means electricity has difficulty travelling through it. But a lightning bolt has already travelled through several kilometres of air (which is also a good insulator) so a few centimetres of rubber will do almost nothing to stop it. The best way to stop lightning is to make sure it has an easier path somewhere else, like through a metal lightning rod.
The metal cage surrounding the High Voltage equipment is called a Faraday cage. It protects us from the electricity produced by the high voltage equipment in the cage. It also blocks radio waves or magnetic fields produced by the high voltage equipment, which can interfere with electronic devices.
If I touch the cage after the tesla coil has stopped, will I receive a shock?
No. The cage is connected to the ground. This allows the electricity to quickly travel into the ground, where it is safely dispersed.
Everything around us – even your own body – is filled with electric charges. For electricity to easily pass through a material, the material must have lots of free electrical charges. Metal has lots of electrical charges that can move freely, so electricity moves through it easily. Materials like rubber or glass have few free charges, so electricity does not move through them easily.
The human body is mostly made of water, with lots of salts and other chemicals dissolved in it. These dissolved salts and chemicals mean there are lots of free electrical charges that can move around. Dry wood has less dissolved salts and chemicals, so electricity cannot travel through it so easily.