The protein or membrane environment could respond to an external field in a number of different ways.

The treatment given so far is for a system not subject to an external electric field.

The Stark effect - splitting because of an external electric field.

Namely, the spin site wants to line up with the external field.

One day, all power to the ship is knocked out, caused by an external field.

I've not yet had the opportunity to translate any living thing in the external field.

One example is the case of nuclear spins in a strong external magnetic field.

However, this system will be affected by an external electric field.

The same will be true when a varying external field is increasing in strength.

I would like to make a few special comments about budget implementation in the external fields.