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oops...sorry I thought you were interested in the source documents for EMP - I realized that you were asking for follow-up on why individual components are not as vulnerable.

EMP energy is spread out in frequency from about 10kHz to 1000MHz.

At 1000MHz, the wavelength is roughly 12 inches. So a half or a quarter wavelength (about 4 inches) would absorb energy efficiently around 1000MHz. Anything smaller, would be inefficient at absorbing energy at 1000MHz.

So your iphone is probably safe - if it’s not charging.

At 10kHz, the wavelength is approximately 19 miles. So at a quarter wavelength, just call it 5 miles you would have an efficient absorber of energy at 10kHz

Now, an EMP has most of it’s energy below about 300MHz - so you might be able to assume that a fairly robust piece of electronics, as long as it (and its conductors) was smaller than 10 inches might have a fair chance of weathering an EMP.

The problem is, you can’t predict where EMP fields are going to come from. You can’t know how efficient your piece of equipment or spare part will be in absorbing EMP energy. It’s entirely possible that you could place two identical parts on a table, but vary their orientation by 90 degrees - and one would be fine, the other junk after an EMP.

So for smaller parts - just give them a little extra help - put them in a mylar bag - at high frequencies they do an OK job of shielding. At low frequencies, they aren’t as good, but your part is so small that it’s not going to absorb much low-frequency energy.

If you want to be extra prudent, put them in a faraday cage of some sort.

The point is that if something is very critical to you take that into account when providing protection for it.

I hope this explanation helps.