Resistance of human body

We have seen that an unknown resistance can be measured by comparing with a known resistance by connecting them in series and measuring the voltages across them. This technique can be used to measure the resistance of human body.

Objective

Measure the resistance of human body by comparing it with a known resistor, for DC and AC voltages.

Procedure

Set PV1 to 3 volts
Connect a wire from PV1 to A1
Connect one end of a wire to PV1
Connect one end of another wire to A2
Connect a 100Ω resistor from A2 to ground.
Enable the Checkboxes to display A1 and A2
Hold the unconnected ends of both wires by your hands.
Repeat using SINE instead of PV1.
Enable amplitude and frequency display for A1 and A2.

Discussion

The AC resistance is less than the DC resistance. The resistance is due to our skin and AC can pass through this, like it passes through the dielectric material of a capacitor. A bit of exploring will reveal that a capacitor is formed between the tip of the wire and blood inside with the skin acting as a dielectric. Explore the effect of a metal plate at the tip of the wire.