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Questions and Answers
What happens when a magnet is divided into smaller pieces according to the dipole law?
What happens when a magnet is divided into smaller pieces according to the dipole law?
- The original magnetic field is diminished.
- Each piece retains both north and south poles. (correct)
- It creates a smaller magnet with only one pole.
- The magnet becomes a single larger magnet.
What is a characteristic of a shell type transformer?
What is a characteristic of a shell type transformer?
- It has a single core with multiple primary coils.
- It has no winding.
- It uses only iron sheets for its core.
- Both coils are wound around a central limb. (correct)
Which of the following materials is classified as ferromagnetic?
Which of the following materials is classified as ferromagnetic?
- Copper
- Gold
- Silicon
- Nickel (correct)
How do like magnetic poles behave towards each other?
How do like magnetic poles behave towards each other?
What type of transformer has one winding and varies voltage and current by self-induction?
What type of transformer has one winding and varies voltage and current by self-induction?
What does electric charge concentration refer to?
What does electric charge concentration refer to?
Which of the following describes direct current (DC)?
Which of the following describes direct current (DC)?
What does Coulomb’s Law formula calculate?
What does Coulomb’s Law formula calculate?
What are conductors best characterized by?
What are conductors best characterized by?
In what situation is it necessary to use rectifiers?
In what situation is it necessary to use rectifiers?
Which formula represents electric power?
Which formula represents electric power?
What characteristic is true of alternating current (AC)?
What characteristic is true of alternating current (AC)?
What is a Magnetic Domain?
What is a Magnetic Domain?
What is the primary study focus of electromagnetism?
What is the primary study focus of electromagnetism?
Which law states that the direction of induced current opposes the action that induces it?
Which law states that the direction of induced current opposes the action that induces it?
What distinguishes a permanent magnet from an electromagnet?
What distinguishes a permanent magnet from an electromagnet?
Which of the following describes magnetic permeability?
Which of the following describes magnetic permeability?
What is an electric generator primarily used for?
What is an electric generator primarily used for?
Which type of magnet is affected by an electric current?
Which type of magnet is affected by an electric current?
Which of the following materials is expected to be non/diamagnetic?
Which of the following materials is expected to be non/diamagnetic?
Who is credited with the discovery of induction?
Who is credited with the discovery of induction?
What occurs due to the movement of negative electric charges?
What occurs due to the movement of negative electric charges?
Which material is classified as a superconductor?
Which material is classified as a superconductor?
What is the primary interaction in the method of electrification known as contact?
What is the primary interaction in the method of electrification known as contact?
According to Coulomb’s Law, what factors does the electrostatic force depend on?
According to Coulomb’s Law, what factors does the electrostatic force depend on?
Which of the following accurately describes an insulator?
Which of the following accurately describes an insulator?
What is the formula represented by Ohm’s Law?
What is the formula represented by Ohm’s Law?
What type of electric current flows in one direction?
What type of electric current flows in one direction?
What is true about the charges of protons and electrons?
What is true about the charges of protons and electrons?
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Study Notes
Electrification and Electric Charges
- Electrification results from the movement of electric charges, primarily negative electrons.
- Insulators do not permit electron flow; examples include glass, plastic, wood, rubber, and paper.
- Semiconductors, like silicon and germanium, can function as either conductors or insulators depending on conditions.
- Superconductors, such as niobium and titanium, allow electron flow without resistance.
- Electric charges: protons (+), electrons (-), and neutrons (0); a single electron holds a charge of 1.6 x 10^-19 Coulombs.
Methods of Electrification
- Contact: Charge transfer occurs when two objects touch.
- Friction: Rubbing two objects together generates charges.
- Induction: Charging occurs without direct contact between objects.
Laws of Electricity
- Ohm's Law: V = IR, relating voltage (V), current (I), and resistance (R).
- Electric current is the flow of electric charge, typically carried by moving electrons in conductors.
Types of Electric Current
- Direct Current (DC): Flows in one direction, sourced from batteries, fuel cells, solar cells.
- Alternating Current (AC): Electrons oscillate back and forth, e.g., from power plants (60Hz).
Electrostatic Principles
- Unlike charges attract; like charges repel.
- Coulomb’s Law: Electrostatic force correlates to the charges and inversely to the square of their distance.
- Electric charge distribution is uniform, while concentration occurs at the surface edges.
Electric Power
- Power (P) is the rate at which electric energy is transferred, given by P = IV or P = I²R, where:
- P = power (Watts)
- V = voltage (Volts)
- I = current (Amperes)
- R = resistance (Ohms)
Magnetism and Electromagnetism
- Magnetism is the force causing attraction or repulsion between magnetic objects.
- Magnetic permeability is a material's ability to attract magnetic field lines; susceptibility measures how easily a material can be magnetized.
- Michael Faraday discovered induction in 1831, while Heinrich Lenz formulated the law of electromagnetism.
Electric Generators and Motors
- Electric generators transform mechanical energy into electrical energy.
- Electric motors convert electrical energy to mechanical energy.
- Transformers modify voltage in an electrical circuit; types include:
- Closed core transformers
- Shell-type transformers (most efficient)
- Autotransformers (vary voltage by self-induction)
States of Matter in Electricity and Magnetism
- Conductors allow electron flow (e.g., copper, gold).
- Non/Diamagnetic materials do not retain magnetic properties (e.g., wood).
- Paramagnetic materials possess intermediate magnetic properties (e.g., gadolinium).
- Ferromagnetic materials can be strongly magnetized (e.g., aluminum, nickel, cobalt).
Magnetic Laws
- Magnet division results in smaller magnets with distinct north and south poles.
- Attraction occurs between unlike magnetic poles; like poles repel.
- Earth's magnetic field measures about 50 microTesla at the equator.
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