Question: Can you explain an EMP ? What are the chances of an EMP ? If an EMP did occur how long would it take to get back to normal ?

Shane Mc Guinness answered on 12 Nov 2013:

Electromagnetic pulses! I’ve always found these so cool! Great question. Basically an EMP is an high energy magnetic wave moving through the air invisibly. It’s like a REALLY strong magnet moving through the air. Magnetism affects electricity in strange ways. Like when you drive under big powerlines and the car radio goes all fuzzy. Well, that’s the opposite happening. Lots of electricity changing the magnetic field (and the radio waves) of your radio.
So with a big explosion, like a nuclear bomb, a huge amount of energy is released in the form of fire, movement (the blast itself) and electromagnetic energy (= the EMP)! If it’s strong enough, this affects electricity so much that it damages electrical equipment like computers and phones or stops the electricity from flowing for a while. Things can recover from this but not always. It depends on the energy of the blast.
Humans are pretty good at dealing with these things, and some devices already have protection from such things. I can’t say how long, but I don’t think it would take too long to recover.