Electricity

    Electricity is the movement of charges.  There are two types of charges, positive and negative.  When these charges separate from each other or move relative to each other we are aware of electricity. 

     People first became aware of the effects of electricity from lightning storms.  Seeing the flashes of light and hearing loud thunder rolling overhead was terrifying.  It was interesting too.  There was other evidence of electricity too.  If you have ever combed your hair on a dry day you know what happens.  You move the comb away from your hair but some hair sticks and you hear a quiet zap!  That sound is made by the movement of charges. 

 

     To understand electricity better we have to understand how charges interact. What do you think happens when a positive charge gets near a negative charge?  To find out click here.  What do you think will happen if two positive charges are brought together?  What do you think will happen if two negative charges are brought together?

     So far we have learned that only opposite charges attract.  So if you have a lot of negative charges in one place and a lot of positive charges in another place they attract.  That can be very dramatic!

     That is how lightning happens.  The clouds have one type of charge and the ground has the other charge.  Then Zap!  Lightning strikes.  This sudden movement of charge is called a discharge.  After a discharge the cloud has the same number of positive and negative charges.  When something has the same number of positive and negative charges we say that it is not charged or neutral.

Now lets watch something get charged! (The video may take a while to load please be patient.)

 

 

Things to try:

 

1.  When the weather is very dry run a comb through your hair.  As you pull away the comb watch your hair try to follow it. 

 

2.  Rub a balloon on your hair.  See if you can get your hair to stick to the balloon.  See if the balloon will stick to anything else.

 

 

Electric Currents

 

     An electric current is different from an electric discharge because an electric current is a steady flow.  We used electric currents to make many of our machines and toys work.  Most of the time electric currents flow through wires. To watch a video about circuits click here.

     An electric current in a wire is like water in a pipe.  In a pipe water flows.  In a wire electric charges flow.  Water running from a high point to a low point can power a watermill.  Charges running from one side of the battery to another can power electric motors. 

 

Things to try:

 

1.  See how many machines in your home run on electricity.