Question

Using an ohmmeter, a student measures the resistance between various points on his body. They find that the resistance between two points on the same finger is about the same as the resistance between two points on opposite hands—both are several hundred thousand ohms. Furthermore, the resistance decreases when more skin is brought into contact with the probes of the ohmmeter. Finally, there is a dramatic drop in resistance (to a few thousand ohms) when the skin is wet. Explain these observations and their implications regarding skin and internal resistance of the human body.

a) Skin acts as a conductor.

b) Skin resistance depends on moisture.

c) Internal resistance varies with contact points.

d) All of the above.

Answer 1

Skin acts as a conductor, skin resistance depends on moisture, and internal resistance varies with contact points.

Step-by-step explanation:

The observations can be explained by the following:

a) Skin acts as a conductor: When the student measures the resistance between various points on his body, he finds that the resistance between two points on the same finger is about the same as the resistance between two points on opposite hands. This indicates that skin acts as a conductor, allowing the flow of electric current.

b) Skin resistance depends on moisture: The resistance decreases when more skin is brought into contact with the probes of the ohmmeter, and there is a dramatic drop in resistance when the skin is wet. This is because moisture, in the form of salts and ions, lowers the resistivity of the skin, making it a better conductor.

c) Internal resistance varies with contact points: The variations in resistance between different contact points on the body suggest that the internal resistance of the human body can vary depending on the path of the current flow.