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Using the same principles that the body uses to defend itself, scientists use vaccines to trigger the body’s adaptive immune system, without exposing humans to the full strength disease. This has resulted in many vaccines, which each work uniquely, separated into many different types.

First, we have live attenuated vaccines. These are made of the pathogen itself, but a much weaker and tamer version.

Next, we have inactive vaccines, in which the pathogens have been killed. The weakening and inactivation in both types of vaccine ensures that pathogens don’t develop into the full-blown disease. But just like a disease, they trigger an immune response, teaching the body to recognize and attack by making a profile of pathogens in preparation.

Another type, the subunit vaccine, is only made from one part of the pathogen, called an antigen, the ingredient that actually triggers the immune response. By even further isolating specific components of antigens, like proteins or polysaccharides, these vaccines can prompt specific responses.

Scientists are now building a whole new range of vaccines called DNA vaccines. For this variety, they isolate the very genes that make the specific antigens the body needs to trigger its immune response to specific pathogens. When injected into the human body, those genes instruct cells in the body to make the antigens. This causes a stronger immune response and prepares the body for any future threats, and because the vaccine only includes specific genetic material, it doesn’t include any other ingredients from the rest of the pathogen.

If these vaccines become a success, we might be able to build more effective treatments for invasive pathogens in years to come.

To learn more about the body’s adaptive immune system and how vaccines work, watch the TED-Ed Lesson How do vaccines work? - Kelwalin Dhanasarnsombut

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High Current/Amps through metal

Any metal that can conduct low voltage / high amperage electricity acts as a resistor between two electrode wires (as in the case above), which are made out of copper, which has a better conductivity than iron/steel which heats up due to the extreme electrical resistance. 

Copper (Cu):

Resistivity: ρ(Ω·m) at 20ºC = 1.68×10−8

Conductivity: σ (S/m) at 20ºC = 5.96×107 

Temp. Coefficient:  0.003862 (K−1)

Iron (Fe): (although what you see in the gif is steel, iron comes pretty close)

Resistivity: ρ(Ω m) at 20ºC = 1.00×10−7

Conductivity: σ (S/m) at 20ºC = 1.00×107

Temp. Coefficient: 0.005 (K−1)

The mathematician Archimedes once said, “Give me a place to stand, and I shall move the Earth.” As it turns out, he was describing the fundamental principle behind the lever.