system
Given the following post, respond as if you're commenting on Reddit:
human
What causes the EMP in a nuclear explosion?

My next question would then be: If a nuclear bomb was detonated in a vacuum on Earth, would it still cause the same EMP?

Thanks!
gpt
A magnetic field is generated when there is a changing electric field.  A nuclear blast releases a lot of electrically charged particles, and it accelerates them very rapidly.  Rapid release of charged particles as well as their violent motion creates a massive magnetic field. 

On the same token a changing magnetic field generates an electric field, so for simplicity you can think of the blast generating a ring of powerful magnetic field around the center, which in turn generates an electric field a little bit further away, which generates a magnetic field a little further away...

Your question asks if it would create the same pulse if it was detonated in vacuum.  The answer is yes there will be a pulse, but no, it would not be the same. If the blast is in vacuum, the pulse is due only to the material in the bomb that is ionized and accelerated.  If the blast is not in vacuum, the blast will not only ionize material from the bomb, but it will also ionize material from whatever medium it is in.  Additional charged particles appearing as well as being accelerated means bigger electromagnetic pulse.