Electricity and the Human Body

Electricity and the Human Body

By Rachel Wampler

Thermal Hazards

Multiple Choice

How much power is dissipated in a short circuit of 240 V AC through a wire with R of 0.250 Ω? What current flows?

• 124 V

  1000 A

• 124 V

  960 A

• 230 kW

  1000 A

• 230 kW

  960 A

Shock Hazards

• Factors:

  • Amount of current

  • Path of current

  • Duration of shock

  • Frequency of current

• Human body is mainly water and electrolytes, so it's a decent conductor​

• Muscles are controlled by electrical nerve impulses

  • A shock can cause a muscle to contract violently

    • Causes victim to close their fist around wire tightly

• Shocks can cause the heart to stop

• Human body is most sensitive at 50-60 Hz​

Multiple Choice

Find the current through a person and identify the likely effect on them if they touch a 120-V AC source: they are standing barefoot on wet grass and has a R of only 4000 kΩ.

• 26.7 mA

  Muscular contraction for duration of the shock

• 0.400 mA

  No effect

• 26.7 mA

  No effect

• 0.400 mA

  Muscular contraction for duration of the shock