Physics Chapter 1: Electric Charge and Atoms

Disclaimer

• This presentation, including examples, images, and references, is for informational purposes only
• Credits for images are given to open-source sources
• Images will not be used in any promotional activities

Lesson 1

• The lesson covers electric charge, Coulomb's Law, electric field, and electric flux
• Electric charge is derived from the Greek word "Elektron" which means "Amber"

The Structure of an Atom

• Atoms are composed of three subatomic particles: protons, neutrons, and electrons
• Protons and neutrons are located in the nucleus at the center of the atom
• Electrons orbit the nucleus in energy levels

The Sub-atomic Particles

• Proton: Relative size (exaggerated), Mass (1.67 x 10^-27 kg), Charge (+1.602 x 10^-19 C)
• Neutron: Relative size (exaggerated), Mass (1.67 x 10^-27 kg), Charge (0)
• Electron: Relative size (exaggerated), Mass (9.11 x 10^-31 kg), Charge (-1.602 x 10^-19 C)

Charge is Quantized

• All charge objects have a charge that is a whole number multiple of the charge of a single electron or proton.
• Electron charge: -e = -1.60 x 10^-19 C
• Proton charge: +e = +1.60 x 10^-19 C
• Neutron: electrically neutral

Conservation of Electric Charge

• The total charge in the universe is constant
• No physical process can result in an increase or decrease in the total charge of the universe

Conductors and Insulators

• Conductors: Allow charges to move freely
• Insulators: Charges are not free to move

5 Electrical Conductors

• Silver
• Gold
• Copper
• Steel
• Sea water

5 Electrical Insulators

• Rubber
• Glass
• Oil
• Diamond
• Dry wood

Semiconductors

• Can be made to behave sometimes as an insulator and sometimes as a conductor
• Examples include Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), and Tellurium (Te)

Superconductors

• Possess infinite conductivity to the flow of charge
• Current passes without losing energy at a critical temperature

Gravity vs Electric Force

• Gravity: Origin - masses, Formula - F = Gm₁m₂/r², Type of force - Attractive
• Electric force: Origin - charges, Formula - F = Kq₁q₂/r²; Type of force - Attractive/Repulsive

Coulomb's Law

• The magnitude of the electric force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them
• k = 8.99 × 10⁹ N m²/C²
• ɛ₀ = permittivity of free space = 1/(4πε₀)

Electric Field

• The amount of electric force per unit charge
• More field lines = stronger electric field
• Closer field lines = stronger electric field
• Lines start from positive and end on negative charges
• Field lines never cross
• Direction of force = direction of electric field
• E = kq/r² (electric field intensity)

Other Important Notes

• Various examples and calculations relating to electric charges are included in the notes