External barrier is any external palisade/domain that secures the internal contents or concepts either as concrete/discreet or abstract forms.
1.Physical external barriers mean barricades/fences from any internal domain.
2.Social external barrier means all socio-cultural elements that are confined within a community/society that prevents any external influence.
Other external barriers:
1.External Psychological barrier
2.External cognitive barriers
3.External Business economics/Finance barrier.
Skin
Skin cells.
The Great Barrier Reef poses no threat to any species. It is the species that already live within the waters of the Great Barrier Reef that are under threat from external sources.
cell membrane
language barrier poor infrastructure in some countries
external
Exactly in forward bias wen internal barrier potential is compensated by external voltage.,
The Great Barrier Reef is being threatened by urban development, agriculture, oil spills, and normal pollution. Infestation and disease have damaged it. Thousands of commercial vessels have damaged it.
To make a barrier between dirty hands and some external substance : which might be either more or less sterile.
Eddy currents are electric currents that are produced inside conductors, through the process of changing the magnetic field in the conductor. The external magnetic field is used as a barrier or skin to protect the eddy.
One external communication barrier is noise (like traffic, birds etc). Lanuage is also an external barrier to communication: if two people speak different languages; it is difficult to communicate. What about time? If there is little or no time to talk, then it will be difficult to communicate effectively. Hope some of this helps.
Skin is the first physical barrier to external damage. It has alerting system owing to pain and temperature sensations. Body's immune system for any possible threat through orifices or surfaces not covered by skin. The norepinephrine signal of fight, flight, freezing with fear on perception of threat from external physical or emotional sources helps prevent from external damage.