Question
A person with body resistance between his hands of $10.0\textrm{ k}\Omega$ accidentally grasps the terminals of a 20.0-kV power supply. (Do NOT do this!) (a) Draw a circuit diagram to represent the situation. (b) If the internal resistance of the power supply is $2000\textrm{ }\Omega$ , what is the current through his body? (c) What is the power dissipated in his body? (d) If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in this situation to be 1.00 mA or less? (e) Will this modification compromise the effectiveness of the power supply for driving low-resistance devices? Explain your reasoning.
1. Please see the solution video
2. $1.67\textrm{ A}$
3. $27.8\textrm{ kW}$
4. $20.0\textrm{ M}\Omega$
5. The power supply can be effective only with low current, which is still possible with low resistance devices if the voltage is low enough. For example, with a $500\textrm{ }\Omega$ device, the current would be only 1.00 mA if the voltage was only 2.50 V.

# OpenStax College Physics for AP® Courses, Chapter 21, Problem 26 (Problems & Exercises)

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