Chapter 19, Problem 64GP

To determine

The method to connect the resistance to obtain desired voltage.

Answer to Problem 64GP

The one resistor of resistance $72000\Omega$ should be connected in series connection with human resistance to obtain desired voltage.

Explanation of Solution

Given info:

The potential difference between the two points on human body is, $v=0.25\text{V}$ .

The resistance of the human body is, $r=2000\Omega$ .

The voltage of the battery is, $V=9\text{V}$ .

Formula Used:

The expression to calculate the current in the human body is,

  $I=\frac{v}{r}$

The expression to calculate the resistance that produces the desired voltage is,

  $R=\frac{V}{I}$

Calculation:

Substitute all the values in the above expression.

  $\begin{array}{c}I=\frac{0.25\text{V}}{2000\Omega }\\ =1.25\times {10}^{-4}\text{A}\end{array}$

Substitute all the values in the above expression.

  $\begin{array}{c}R=\frac{9\text{V}}{1.25\times {10}^{-4}\text{A}}\\ =72000\Omega \end{array}$

The voltage drop in the parallel connection remains constant across each resistance and voltage drop occurs in the series connection of the resistance. The resistance of the value $72000\Omega$ must be connect in the series connection with resistance of the human body to obtain the desired voltage.

Conclusion:

Thus, the one resistor of resistance $72000\Omega$ should be connected in series connection with human resistance to obtain desired voltage.