Define potential difference as used in electricity

This ability of charged particles to do work is called an electric potential.

Explanation:

When two negative charges are brought close to each other, they also repel. But when a positive and a negative charge are brought close together, they attract each other. When these two opposite charges are combined, they can be used to work. This is why we need a positive (+) and a negative (–) to light a bulb or run any electrical tool, equipment, mobile phone or home appliance.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

neither accurate nor precise.