Electricity and Magnetism Study Sheet

Key Vocabulary

• Charge: Property of matter causing electric forces.

• Circuit: Path for electric current.

• Conductor: Material that allows electric current to flow easily (e.g., copper, aluminum).

• Insulator: Material that does not conduct electricity well (e.g., rubber, plastic).

• Electric Cell: Device that produces electric current.

• Electric Current: Flow of electric charge (electrons).

• Static Electricity: Electric charge at rest, often caused by friction.

• Magnet: Object that produces a magnetic field.

• Magnetic Field: Area around a magnet where magnetic forces act.

• Magnetic Pole: Ends of a magnet (North and South).

• Electromagnet: Temporary magnet created by electric current through a wire coil.

• Resistor: Component that resists electric current.

• Series Circuit: Circuit with one path for current.

• Parallel Circuit: Circuit with multiple paths for current.

Concepts

Static Electricity

• Caused by friction (rubbing materials).

• Objects gain or lose electrons, becoming charged.

• Like charges repel; unlike charges attract.

• Static discharge can occur (e.g., lightning).

Current Electricity

• Produced by electric cells or power sources.

• Requires a closed circuit for electrons to flow.

• Components of a circuit: power source, conductor (wire), load (device), and switch.

Circuits

• Closed Circuit: Complete path, current flows.

• Open Circuit: Broken path, no current flows.

• Series Circuit: One path; if one component fails, all stop working.

• Parallel Circuit: Multiple paths; if one component fails, others continue working.

Conductors and Insulators

• Conductors allow current flow (e.g., metals).

• Insulators block current flow (e.g., plastic coating on wires).

Electromagnetism

• Electric current creates a magnetic field.

• Moving magnetic fields can induce electric current.

• Electromagnets are made by wrapping wire around iron and passing current.

• Strength depends on number of coils and current strength.

• Used in motors, transformers, and magnetic cranes.

Ohm’s Law

• Relationship between Voltage (V), Current (I), and Resistance (R):

  • V = I × R

  • I = V / R

  • R = V / I

• Voltage is potential difference.

• Resistance opposes current flow.

Sample Problems

1. Find current: V = 9V, R = 18Ω
   I = V / R = 9 / 18 = 0.5 A

2. Find current: V = 110V, R = 2200Ω
   I = 110 / 2200 = 0.05 A

3. Find voltage: I = 0.1 A, R = 40Ω
   V = I × R = 0.1 × 40 = 4 V

Important Notes

• Magnets have two poles: North and South.

• Like poles repel; unlike poles attract.

• Magnetic force is strongest at the poles.

• Permanent magnets keep magnetism; electromagnets are temporary.

• Electricity and magnetism are closely related phenomena.