Electricity and Electronics

Brad Dearing108 University High School

Normal, IL 61761

(309) 438-5513

bmdeari@ilstu.edu

The Nature of Matter• Matter – anything that has mass and takes up space.

– Element – the most basic form of a substance.(Sodium) or (Chlorine)

• Compound – the combination of two or more elements. (Salt)

• Molecule – the smallest part of a compound that still retains its unique properties. (One small piece of salt)

– Atom – smallest part of an element (one sodium atom)• Electrons – Negative part of atom (11 electrons in Na)

• Protons – Positive part of atom (11 protons in Na)

• Neutrons – No charge or neutral part of atom (11.990 neutrons in Na)

Ionization

• Ionization occurs when an atom gains or loses an electron.– Positive Ion – more protons than electrons in an

atom (loses an electron)– Negative Ion – more electrons than protons in

an atom (gains an electron)

Static Electricity

• Electricity at rest (static)

• Stationary charge

• Produced by friction

• Law of charges: Like charges repel each other and unlike charges attract each other.

Terms

• Coulomb – the measurement of the amount of electricity. 1 coulomb = 6.24 x 1018 electrons

• Electrostatic Fields – the field of force surrounding a charged body. (dielectric field)

See next slide

• Induction – the transfer of a charge without direct contact, bringing it close to another object.

Basic Electrical Circuit

• Source of voltage (battery)

• Load (lamp)

• Conductors (wires)

Polarity

Terms

• Battery – form of DC electricity, generally by chemical reaction.

• Load – when electrical energy is converted to some other form of energy. (i.e. light, heat, magnetism, etc.)

• Conductor – pathway conducive to carrying electricity, generally coated with a protective coating.

Terms

• Voltage – the force behind electron flow. (volts: V) aka: potential, potential difference, or electromotive force (emf) (E)

• Current – the flow of electrons. (ampere: A) (I) 1 amp = 1 coulomb of charge flowing past a point in one second.

• Resistance – the opposition to the flow of electrons. (ohms: )

Terms

• Conductor – anything that permits the free flow of electrons.

• Insulator – extremely poor conductors.

• Semiconductor – a material that limits the flow of electrons, considered neither a good conductor nor a poor conductor.

See table of common conductors and insulators p. 27

Current • AC – Alternating Current: flows in both directions. (household current) (Cycle or hertz: Hz)

• DC – Direct Current: flows in only one direction in a circuit. (battery)

Electron Flow Theory• Conventional current

flow theory – positive to negative.

• Electron flow theory – negative to positive.

Series and Parallel

Ohm’s Law

E = I x R

I = E / R

R = E / I

voltage

current

resistance