On National Teacher Day, meet the 2024-25 Kenan Fellows
electric charge (3rd q).pptx protons and neutrons
1. 1
Let’s Connect
• What is electricity?
Electricity is the set of physical
phenomena associated with the presence and
motion of matter possessing an electric
charge.
• What is electricity made of?
3. 3
Atoms & Electricity
• All matter is made of atoms, which contain
electrons, protons, and neutrons.
• Objects normally contain equal numbers of
electrons and protons: such objects are called
neutral.
• When an object has an imbalance in the
number of electrons and protons, it is
electrically charged.
• Neutrons are not involved in electric
interactions.
4. 4
Electric Charge
• An object with more electrons than protons is
said to carry a negative charge.
• An object with more protons than electrons is
said to carry a positive charge.
5. 5
Electric Charge
• Electric charge is a conserved quantity:
Charge cannot be created nor destroyed,
but it can be transferred between objects.
• Charged objects exert electric forces on each
other:
Opposite charges attract;
Like charges repel.
6. 6
Units for Electric Charge
• The symbol for electric charge is usually a “q”.
• The elementary charge unit (e) is equal to the
charge of a single proton or electron:
qproton = +1e
qelectron = –1e
• The elementary charge unit is not the standard SI
unit.
• The SI system uses the Coulomb (C) as the
standard unit of charge.
7. 7
Units for Electric Charge
• A Coulomb is defined as the number of electrons
passing through a current of 1 Amp each second:
C = A·s.
• The conversion between C and e was determined
by Robert A. Millikan:
1 e = 1.60×10–19 C.
8. Polarization
• In some cases, neutral objects may be
electrically active through a phenomenon
known as polarization.
• When a charge (either + or –) is brought
near a neutral object, the electrons and
protons are pushed in opposite directions.
8
9. Polarization
• The two edges of the object acquire
opposite charges. The object is polarized.
• The near side is attracted and the far side
is repelled.
• The attraction is stronger because it is
closer.
9
10. Polarization
• The net force is attractive.
• If a – charge is used instead of a + one, the
net force is still attractive.
• If they can be polarized, neutral objects
will attract to both + and – charges.
10
11. How can a neutral object be
electrically charged?
12. 12
Electric Charge
• There are three common ways for a neutral
object to become charged.
1.Friction
2.Conduction
3.Induction
