If you touch the terminal of a battery, the small area of...

If you touch the terminal of a battery, the small area of contact means that the skin resistance will be relatively large; $50 \mathrm{k} \Omega$ is a reasonable value. What current will pass through your body if you touch the two terminals of a $9.0 \mathrm{V}$ battery with your two hands? Will you feel it? Will it be dangerous?

Key Concepts

Electrical Safety

Electrical safety pertains to the assessment of risk when the human body is exposed to electric currents. It involves understanding the levels of current that can be dangerous, as well as the duration and path the current takes through the body. Generally, low currents, especially those below the perceptible threshold, are unlikely to cause harm, while higher currents can pose serious risks such as tissue damage or heart arrhythmias.

Thresholds of Electrical Sensation

Thresholds of electrical sensation describe the minimum amount of current that can be perceived by the human body. Typically, currents in the range of a few milliamperes can be felt, although very small currents may be imperceptible. Understanding these thresholds is important in evaluating whether an electrical shock will be noticeable or potentially harmful.

Skin Resistance

Skin resistance refers to the natural resistance offered by the human skin to the flow of electrical current. It varies depending on factors such as the moisture and thickness of the skin, as well as the area of contact. A smaller contact area, or dry skin, significantly increases the resistance, reducing the current that can pass through the body when in contact with a voltage source.

Ohm's Law

Ohm's Law is a fundamental principle in electrical circuits stating that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. This law is expressed with the formula I = V/R, which allows the calculation of current when voltage and resistance are known.

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