Final answer:
High voltage power lines can pose two main hazards: thermal hazards and shock hazards. Thermal hazards can cause fires due to excessive electric current, while shock hazards can result in electric shock, ranging from painful to lethal.
Step-by-step explanation:
People who encounter high voltage power lines can be injured and may die due to two main hazards: thermal hazards and shock hazards.
Thermal Hazards:
An excessive electric current can cause undesired thermal effects, such as starting a fire in the wall of a house. For example, if there is a short circuit, where a low-resistance path is created between terminals of a voltage source, the thermal energy generated can quickly raise the temperature of surrounding materials, potentially causing a fire.
Shock Hazards:
Electric shock occurs when an electric current passes through a person. The severity of electric shocks can range from painful but harmless to heart-stopping lethality. When a current with a magnitude above 300 mA passes through the heart, death may occur.