alleryStart learning →A technician standing on a rubber mat has a total resistance of 300 kilohms. What current flows if the technician touches a 120-V AC source?
A4.00 mA
B0.400 mA
C40.0 mA
D2.50 mA
Answer & Solution
Correct answer: B. 0.400 mA
1. Use Ohm's law: I = V/R.
2. Convert the resistance: 300 kilohms = 300,000 ohms.
3. Divide: I = 120 V / 300,000 ohms = 0.000400 A.
4. Convert to milliamperes: I = 0.400 mA.
5. That is below the 1-mA threshold of sensation, so the shock passes unfelt; 40.0 mA is the trap of treating 300 kilohms as 3,000 ohms.
_Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.6 Electric Hazards and the Human Body_
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