Touching both terminals of a battery

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Discussion Overview

The discussion revolves around the phenomenon of electric shock when touching both terminals of a 9V battery, exploring the reasons why individuals do not typically experience shocks in this scenario. Participants examine concepts related to voltage, current, skin resistance, and the functioning of multimeters.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why touching both terminals of a battery does not result in an electric shock, suggesting that it seems like completing a circuit.
  • Another participant suggests trying to touch the battery terminals with the tongue, implying a different experience of sensation.
  • Some participants note that using an old analog meter set to AC can display double the actual voltage, indicating a potential misunderstanding of meter settings.
  • It is mentioned that electrical shock is primarily due to current flowing through the body, not just the presence of voltage, with skin resistance playing a significant role in this process.
  • Participants discuss that dry skin has a resistance in the order of tens of KOhm, which may prevent shock unless higher voltages are present.
  • One participant highlights that with wet skin, the resistance decreases, making lower voltages potentially dangerous.
  • Another participant reiterates that while current causes shocks, voltage can intensify the effect.

Areas of Agreement / Disagreement

Participants generally agree on the role of current and skin resistance in the experience of electric shock, but there are varying perspectives on the specifics of voltage thresholds and the effects of different conditions (dry vs. wet skin). The discussion remains unresolved regarding the exact conditions under which shocks may occur.

Contextual Notes

Some participants reference external sources for further reading, but the discussion does not resolve the nuances of how skin resistance varies with conditions or the implications for safety.

BogMonkey
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Sorry if this is the wrong forum. When I just touch any part of the metal of both terminals on a 9V battery with a multimeters probes the meter displays the voltage (although it said 20V not 9V for some reason). What I'm wondering is why people don't get electric shocks from touching both terminals of a battery at once. Wouldn't you be completing the circuit?
 
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Try touching it to your tongue.
 
If you have an old analog meter with a special switch for reading ac volts (e.g. like the Simpson model 260 or the Triplet meter), you do get 2x the actual voltage. The analog meter should be on dc volts for reading batteries. Your skin resistance protects you from shock, up to a limit.

Bob S
 
Electrical shock is due to current flowing through your body, not so much an electric field (voltage). The resistance of your skin and body allows you to obtain the current by ohm's law (although ohm's law is not strictly valid for a human body, in de sense that the resistance is not independent of the voltage). For a dry skin, this resistance is in the order of tens of KOhm.
You start getting problems with currents from a few mA onwards, which means that you need several tens of volts before things get "shocky".

With a wet or immersed body the resistance lowers and there the limit of "dangerous" voltage is lower (hence the example of the tongue).

See for instance http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html
as a starting point.
 
Bob S said:
If you have an old analog meter with a special switch for reading ac volts (e.g. like the Simpson model 260 or the Triplet meter), you do get 2x the actual voltage. The analog meter should be on dc volts for reading batteries. Your skin resistance protects you from shock, up to a limit.

Bob S

Ah right that explains it I bought a "household meter" so its probably build for AC.
 
vanesch said:
Electrical shock is due to current flowing through your body, not so much an electric field (voltage). The resistance of your skin and body allows you to obtain the current by ohm's law (although ohm's law is not strictly valid for a human body, in de sense that the resistance is not independent of the voltage). For a dry skin, this resistance is in the order of tens of KOhm.
You start getting problems with currents from a few mA onwards, which means that you need several tens of volts before things get "shocky".

With a wet or immersed body the resistance lowers and there the limit of "dangerous" voltage is lower (hence the example of the tongue).

See for instance http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html
as a starting point.

Thanks. I didn't know skin had such high resistance.
 
Current gives you the shocks, not voltage. But voltage vill intensify it as it increases.
 

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