Final answer:
A shock greater than 30 mA can disrupt the heart's electrical activity, leading to ventricular fibrillation and potentially fatal outcomes. Currents of about 300 mA and above can also cause burns, with severity depending on various factors such as the current's path and the person's resistance.
Step-by-step explanation:
When a person receives an electric shock greater than 30 mA, it can have serious effects on their health. A current between 100 and 300 mA can disrupt the heart's electrical patterns, leading to a condition known as "ventricular fibrillation". This condition can be fatal due to the heart beating irregularly and the resulting lack of blood circulation. When the current reaches about 300 mA or higher, there is not only a risk of ventricular fibrillation but also the possibility of burns due to the concentration of the current. Therefore, greater currents can have life-threatening consequences for a person, with the severity depending on the amount of current, the path it takes through the body, duration, frequency, and the person's resistance (which varies depending on factors like skin moisture).