Electrification and Electric Charges Quiz

Electrification and Electric Charges

• Electrification occurs through the movement of negative electric charges, primarily electrons.
• Insulators do not allow the flow of electric charges; examples include glass, plastic, wood, rubber, and paper.
• Semi-Conductors have variable conductivity; they can act as either conductors or insulators depending on conditions (e.g., Silicon and Germanium).
• Superconductors enable electron flow without resistance; examples are Niobium and Titanium.

Methods of Electrification

• Contact: Charging occurs when two objects touch.
• Friction: Charging results from rubbing two objects together.
• Induction: Charging an object without direct contact is possible through electric fields.

Properties of Electric Charges

• Proton: Positively charged particle (+).
• Electron: Negatively charged particle (-), where 1 electron = 1.6 x 10^-19 C.
• Neutron: Neutral charge (0).

Ohm’s Law and Electric Current

• Ohm’s Law relates current (I), voltage (V), and resistance (R): V = IR.
• Electric Current: Flow of electric charge through a medium, primarily via moving electrons in conductors.
• Two types of electric current:
  • Direct Current (DC): Continuous flow in one direction (e.g., from batteries).
  • Alternating Current (AC): Current that changes direction, oscillating back and forth (e.g., from power plants, typically 60 Hz).

Electrostatics and Electrostatic Laws

• Electrostatics: The study of stationary electric charges.
• Electrostatic Force: Attraction between unlike charges and repulsion between like charges.
• Coulomb’s Law: Electrostatic force is proportional to the product of charges and inversely proportional to the square of the distance.
• Electric Charge Distribution: Uniform charge distribution on surfaces.
• Electric Charge Concentration: Charges gather at points of sharp curvature.

Electric Power

• Electric Power: Rate of energy transfer in an electric circuit, calculated as P = IV or P = I²R.

Magnetism and Electromagnetism

• Magnetism: Force attracting or repelling objects; includes natural (earth, magnetite) and artificial magnets (e.g., compass).
• Electromagnetism: Interaction between electrically charged particles, governed by the principles of magnetic fields.
• Michael Faraday: Discovered electromagnetic induction and created the first dynamo.

Laws of Electromagnetism

• Faraday’s Law: Magnetic fields cannot generate electric current.
• Lenz's Law: Induced current opposes the inducing action.
• Electric Generator: Converts mechanical energy into electrical energy.
• Electric Motor: Converts electrical energy back into mechanical energy.

Magnetic States of Matter

• Conductor: Materials allowing electron flow (e.g., copper, gold).
• Non/Diamagnetic: Materials unaffected by magnetic fields (e.g., glass, rubber).
• Paramagnetic: Exhibits weak attraction to magnetic fields (e.g., Gadolinium).
• Ferromagnetic: Strongly magnetized materials (e.g., iron, nickel).

Types of Transformers

• Closed Core: Primary and secondary coils on opposite legs.
• Shell Type: Coils wound around a central limb, most efficient design.
• Autotransformer: Single winding that varies voltage and current through self-induction.

Additional Notes

• Earth's magnetic field is about 50 microteslas (µT) at the equator.
• Important concepts include the right-hand rule for magnetic fields: thumb direction for current motion and curled fingers for field direction.