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Man being struck by lightning

Man being struck by lightning (bestdesigns, iStockphoto)

STEM in Context

Do Amps or Volts Kill You?

Let's Talk Science
Format
Video Text Images
Readability
5.06
Subjects

Summary

This resource explains electricity basics - volts, amps, currents, resistance, and why it is dangerous to touch electrical outlets with wet hands.
Do Volts or Amps Kill You? Voltage, Current and Resistance (2014) by RimstarOrg (5:15 min.).

There’s an old saying: "It's not the volts that kills you, it's the amps." That’s true in a way. But that’s not the whole story!

But wait. What are volts and amps? Amps (A) are the unit we use to measure electric current. An electric current is the flow of negatively charged electrons past a given place over a period of time. 

The flow of electrons creates a current. But it does not happen on its own. It needs energy. The amount of energy in each unit of electrical charge is called voltage. Volts (V) is the unit for voltage. 

Have you ever watched water flowing through a pipe? Sometimes it can flow quickly. Sometimes it can flow slowly. It depends on the water pressure. 

Imagine that an electric current is a water pipe. The amps would be like the volume of water. Volts would be like the water pressure. So the amps measure the amount of electricity in a current. The volts measure that electricity’s strength. 

Did you know that your body uses electricity, too? Your muscles, lungs, and heart all need electricity so they can work properly. Electric currents travel well through your blood. But they have a hard time passing through your skin. We can say that your skin resists the flow of electrons. In other words, your skin is a resistor. It helps keep your body safe. 

When the voltage of a current goes up, your skin’s resistance goes down. This lets more current flow through your skin. Has anyone ever told you not to touch a live wire of a downed power line? That is because its voltage is very strong. In fact, its voltage will be high enough to overcome your skin’s resistance. It can pass through your skin into your blood vessels. If the level of amps is high enough, it can do some serious damage to your body tissues. It could even kill you! 

Downed power line
Power line downed by fallen tree (Source: solarisimages via iStockphoto).

If your skin is wet, its resistance will be even lower. Has anyone ever told you not to play in a puddle during a thunderstorm? Or has anyone told you not to touch electrical devices when your hands are wet? Now you know why!

So, is it volts or amps that is dangerous? The answer is both!
 

Starting Points

Connecting and Relating
  • When you use an electrical appliance, how do you make sure you are safe?
  • Which things in your everyday life use electricity? How important are these to you? Would you be able to live without them?
Connecting and Relating
  • When you use an electrical appliance, how do you make sure you are safe?
  • Which things in your everyday life use electricity? How important are these to you? Would you be able to live without them?
Relating Science and Technology to Society and the Environment
  • What are some things we do every day to make sure we don’t get hurt by electricity? Explain. 
  • What are some technologies that have been developed to make electricity safer for people to use?
  • What are some ways that people can get hurt by electricity?
Relating Science and Technology to Society and the Environment
  • What are some things we do every day to make sure we don’t get hurt by electricity? Explain. 
  • What are some technologies that have been developed to make electricity safer for people to use?
  • What are some ways that people can get hurt by electricity?
Exploring Concepts
  • What is electrical energy?
  • Define current, voltage and resistance.
  • Why is the resistance of your skin different when it is wet and when it is dry? 
  • What organs are impacted first by an outside electric current?
Exploring Concepts
  • What is electrical energy?
  • Define current, voltage and resistance.
  • Why is the resistance of your skin different when it is wet and when it is dry? 
  • What organs are impacted first by an outside electric current?
Teaching Suggestions
  • This article can be used in Engineering & Technology and Math & Physics to support teaching and learning related to electricity generation and electrical technologies. Concepts introduced include electricity, electric current, voltage, and resistance.
  • Teachers can use this video as a leading resource to introduce Ohm’s Law.
  • Prior to watching the video, students could complete an Admit Slip learning strategy to introduce the topic and engage prior knowledge. Download ready-to-use reproducibles using the Admit Slip learning strategy for this video in [Google doc] and [PDF] formats.
  • To consolidate understanding of electrical current and resistance, teachers could have students complete a Concept Definition Web learning strategy. Ready-to-use Concept Definition Web reproducibles are available in [Google doc] and [PDF] formats. 
Teaching Suggestions
  • This article can be used in Engineering & Technology and Math & Physics to support teaching and learning related to electricity generation and electrical technologies. Concepts introduced include electricity, electric current, voltage, and resistance.
  • Teachers can use this video as a leading resource to introduce Ohm’s Law.
  • Prior to watching the video, students could complete an Admit Slip learning strategy to introduce the topic and engage prior knowledge. Download ready-to-use reproducibles using the Admit Slip learning strategy for this video in [Google doc] and [PDF] formats.
  • To consolidate understanding of electrical current and resistance, teachers could have students complete a Concept Definition Web learning strategy. Ready-to-use Concept Definition Web reproducibles are available in [Google doc] and [PDF] formats. 

Learn more

What Happens When You Get Electrocuted? (2018)

This SciShow video (3:52 min.) explains how amps and volts can cause electric shock and injury.

Voltage Explained - What is Voltage? Basic electricity potential difference (2018) 

The Engineering Mindset illustrates how voltage works, and the purpose of voltage, to understand electricity with this video (10:51 min).

Basic Electricity - What is an amp? (2011) 

This video (5:40 min.) by Afrotechmods explains how electrical circuits work, and how amps are used to measure the current that flows around them.

What is Electrical Resistance (2018) 

With the help of glass marbles, Nathan Bartolo uses this video (3:00 min.) to illustrate how resistance affects electric current.