PHY 102 PLUS AND PDFS

Physics: Magnetism and Electricity

Magnetism:

- Definition: The force exerted by a magnet on other magnets, electric currents, and moving charges.
- Types:
- Permanent magnets: Magnets that retain their magnetism even after the removal of the external magnetic field.
- Electromagnets: Magnets produced by electric currents flowing through a coil of wire.
- Properties:
- Magnets have two poles: north pole and south pole.
- Like poles repel each other, while unlike poles attract each other.
- Magnetic field lines flow from north pole to south pole.
- Examples:
- Bar magnets, horseshoe magnets, electromagnets, Earth's magnetic field.
- Formulas:
- Magnetic force: F = qvBsinθ, where q is the charge of the moving particle, v is its velocity, B is the magnetic field strength, and θ is the angle between v and B.
- Magnetic flux: Φ = BAcosθ, where B is the magnetic field strength, A is the area of the surface perpendicular to the magnetic field, and θ is the angle between B and the normal to the surface.

Electricity:

- Definition: The flow of electrons through a conductor.
- Types:
- Direct current (DC): Current that flows in one direction only.
- Alternating current (AC): Current that flows back and forth in a regular pattern.
- Properties:
- Current is measured in amperes (A).
- Voltage is measured in volts (V).
- Resistance is measured in ohms (Ω).
- Ohm's law: V = IR, where V is the voltage, I is the current, and R is the resistance.
- Examples:
- Light bulbs, electric motors, radios, televisions.
- Formulas:
- Ohm's law: V = IR
- Power: P = VI, where P is the power, V is the voltage, and I is the current.
- Electrical energy: E = Pt, where E is the energy, P is the power, and t is the time.