Dr Vetrovec intends to perform his version of the trick at atmospheric pressure, and using permanent magnets.

维特威克博士想要在大气压力下使体来实现他的这把戏。

This makes electromagnets quite different from permanent magnets.

这使得体与体有很大不同。

This is different from a permanent magnet because permanent magnets don't need this wire.

这与体不同，因为体不需要这。

So let's take a look at that and compare permanent magnets to electromagnets.

让我们看一下并将体与体进行比较。

Permanent magnets also have fixed poles.

体也有固定极。

On the other hand, permanent magnets are always on.

另一方面，体始终处于开启状态。

Permanent magnets have a fixed strength, but we just talked about how we can change the strength of electromagnets, so electromagnets have adjustable strength.

体的强度是固定的，但是我们刚才讲了如何改变铁的强度，所以铁的强度是可调的。

Permanent magnets do not need a power source, but this means that we can also turn electromagnets on and off, which is pretty cool when you think about it.

体不需要源，但这意味着我们也可以打开和关闭体，想想看，这真是太酷了。