Electricity The Basics

The flow of electricity is actually the flow of _______________. A.Electrons B.Protons C.Electric charge D.Energy

The flow of electricity is actually the flow of _______________. A.Electrons B.Protons C.Electric charge D.Energy

Electricity Its all based on atoms – protons and electrons. – Protons are positive + – Electrons are negative – If electrons move from one atom to another, the first atom becomes positive and the second atom becomes more negative Electric Charges follow a code – Like charges (+,+) repel each other – Opposite charges (+, -) attract each other

When a balloon is rubbed against your hair and pulled away, your hair clings to it because _________. A.Rubber is very sticky B.The balloon is filled with helium C.The hair and balloon are both positively charged D.The hair is positively charged and the balloon is negatively charged

When a balloon is rubbed against your hair and pulled away, your hair clings to it because _________. A.Rubber is very sticky B.The balloon is filled with helium C.The hair and balloon are both positively charged D.The hair is positively charged and the balloon is negatively charged

Static Electricity “Static electricity is caused any time two different materials come in contact and then separate Blanket in the winter Shoes on the carpet Static electricity is present in almost all substancespresent substances The greater the difference in charge the more likely a discharge will occur.difference

Rubbing Rubbing your hair with a balloon increases the static charge because ____________. A.Protons are moving from your hair to the balloon. B.The balloon is getting charge from your hair. C.The rubber in the balloon is non- conducting so it allows the electricity to gather D.Hair and rubber are compatible

Rubbing Rubbing your hair with a balloon increases the static charge because ____________. A.Protons are moving from your hair to the balloon. B.The balloon is getting charge from your hair. C.The rubber in the balloon is non- conducting so it allows the electricity to gather D.Hair and rubber are compatible

ConductorConductor/Insulator Substances which allow for easy electric charge movement are conductors – Metal All other substances are non-conductors or insulators – Glass Some substances can be conductors sometimes and insulators other times and are called semiconductorssemiconductors – microchips

Electric wires are wrapped with rubber or plastic in order to keep you from being electrocuted. This is because the rubber or plastic is a good _____________. A.Insulator B.Conductor C.Transfer point D.Bridge for the electrons

Electric wires are wrapped with rubber or plastic in order to keep you from being electrocuted. This is because the rubber or plastic is a good _____________. A.Insulator B.Conductor C.Transfer point D.Bridge for the electrons

Electric Force Created when objects have a charge. Amount of force depends on amount of charge and distance to another charge Electric force either pushes away (repels) or attracts Amber rubbed with fur picked up small bits of wood and cloth

Electric Force: Coulomb’s Law F = force ; q = charge; r = distance from centers SI Unit for electric charge is coulomb Coulomb’s Constant –k c =8.99 X 10 9 N x m 2 /C 2 F = force ; q = charge; r = distance from centers SI Unit for electric charge is coulomb Coulomb’s Constant –k c =8.99 X 10 9 N x m 2 /C 2

If you put your finger 1 cm from the Vandegraff, it will be attracted to it. If you move your finger to 3 cm from the VGG, the attraction _______. A.Stays the same B.Decreases by 3 C.Triples D.Decreases by 9

If you put your finger 1 cm from the Vandegraff, it will be attracted to it. If you move your finger to 3 cm from the VGG, the attraction _______. A.Stays the same B.Decreases by 3 C.Triples D.Decreases by 9

If I double the charge on one of two objects, the overall impact to the force is _________ A.Doubled B.Halved C.Unchanged D.Quadrupled

If I double the charge on one of two objects, the overall impact to the force is _________ A.Doubled B.Halved C.Unchanged D.Quadrupled

Gravity vs Electricity Gravity – Attractive – Based on distance and mass – Weak force Electricity – Attractive or repulsive – Based on distance and charge – Strong force

Conduction – Charge Sharing A charged object touches a neutral object; the two objects share the charge equally A positively charged object touches an equally charged negative object; the two objects neutralize each other. An object with one unit of negative charge touches an object with three units of negative charge; the objects are left with two units of negative charge each. An object with one unit of negative charge touches an object with three units of positive charge; the objects are left with one unit of positive charge each.

Induction – Safe Charging A negatively charged object (conductor or insulator) is brought near a neutral object (preferably a conductor). Electrons in the neutral object move away from the charged object. The neutral object is grounded somehow. Usually, this is done by touching the object with a finger. This allows the electrons to flee the negative object by traveling to the earth. The grounding connection is broken while the negative object is still nearby. The negative object can be withdrawn. Because the previously neutral object lost electrons in step 3, it is now positively charged.

An object that does not allow electricity to flow is called an insulator. A.True B.False

An object that does not allow electricity to flow is called an insulator. A.True B.False

Charge Quantization Charge cannot take any arbitrary values It can only have values that are integral multiples of the fundamental charge (charge of proton/electron) The fundamental charge is e = 1.602×10 −19 coulombs Quarks (what makes protons, neutrons and other Hadrons) do have 1/3 e or 2/3 e but they have never been isolated, they always come as pairs (muons) or triplets (baryons), so they don’t violate the fundamental charge rule. You must know to challenge any claim on the AP test if they suggest that a charge do not follow this rule!!!