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Electric Shock
17 questions By Tony R. Kuphaldt
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Question 1 of 17
It is sometimes said regarding electrical safety that, Ït’s not the voltage that will hurt you, it’s the current.” Why then are there signs reading Danger: High Voltage near electrical substations and on large pieces of electrical equipment, rather than signs reading Danger: High Current?
Reveal answerYes, it is electric current that does the damage when enough of it passes through a body, but current exists only when there is sufficient voltage to push it through that body’s resistance. Thus, there is no shock hazard when there is too little voltage present to force dangerous levels of current through a human body.
Notes:Ask students how this question relates to Ohm’s Law. If they don’t know what Ohm’s Law is yet, this is a really good place to begin exploring!
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Question 2 of 17
Why is this sign a joke?
Reveal answerElectrical resistance is not hazardous in the least. In fact, the more resistance there is, the less chance there is for electrons to flow, thus minimizing shock hazard.
Notes:A joke it may be, but still a fun one to play. Hang a large sign saying “Danger: high resistance” over the entrance to the electrical lab and watch the responses of the uninitiated!
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Question 3 of 17
Using Ohm’s Law, explain why personal protective equipment such as insulating gloves and boots help reduce the risk of electric shock.
Reveal answerSuch personal protective equipment serves the purpose of increasing electrical resistance in the shock path.
Notes:Ohm’s Law has many applications, and electrical safety is just one of them. I have found that the topic of safety is an excellent venue for highlighting certain (otherwise abstract) physical principles. Not only is the topic interesting, but it is of great personal importance, and so student attention is very easy to attain and hold in discussion.
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