Atomic Structure and Electron Theory
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Questions and Answers

What happens when an atom becomes a positively charged ion?

  • It gains an electron from a nearby atom.
  • It repels all other electrons.
  • It loses an electron to a nearby atom. (correct)
  • It causes an imbalance in electric current.

    • What is the term used for the flow of electrons towards a positively charged source?

  • Current Flow
  • Electro-Motive Force
  • Electron Flow (correct)
  • Electron Drift

    • Which of the following is NOT an effect of electron flow?

  • Magnetic field generation
  • Production of heat
  • Physical movement of the atom (correct)
  • Operation of electric motors

    • What defines the rate of electron flow in a circuit?

    <p>The potential difference across the conductor</p> Signup and view all the answers

    How many electrons are required to equal 1 volt?

    <p>6,250,000,000,000,000,000</p> Signup and view all the answers

    In what type of electricity do electrons move through a circuit and perform work?

    <p>Current electricity</p> Signup and view all the answers

    What is produced by an imbalance in electrical potential?

    <p>Electro-Motive Force</p> Signup and view all the answers

    What occurs when two materials are rubbed together?

    <p>Electrons are wiped off one material onto the other.</p> Signup and view all the answers

    What drives the flow of electrons in a circuit?

    <p>The difference in electrical potential</p> Signup and view all the answers

    What is a characteristic of static electricity?

    <p>It is more of a nuisance than a practical application.</p> Signup and view all the answers

    What is the primary function of a photocell?

    <p>To detect light and control operations</p> Signup and view all the answers

    What determines the amount of electricity produced by electromagnetic induction?

    <p>The rate at which magnetic lines of flux are cut</p> Signup and view all the answers

    Which condition is NOT required to produce a voltage by magnetism?

    <p>A vacuum must exist around the conductor</p> Signup and view all the answers

    What is the main difference between wet cells and dry cells?

    <p>The type of electrolyte used</p> Signup and view all the answers

    Which method can increase the rate of voltage production through electromagnetic induction?

    <p>Increasing the strength of the magnet</p> Signup and view all the answers

    What happens to electrons when a conductor cuts across magnetic lines of force?

    <p>They are propelled in one direction, creating voltage</p> Signup and view all the answers

    In which device is a wet cell commonly found?

    <p>Motor vehicle batteries</p> Signup and view all the answers

    Which of the following statements about electromagnetic induction is true?

    <p>It utilizes relative motion between a conductor and a magnetic field.</p> Signup and view all the answers

    When a loop of wire spins in a magnetic field, what does it generate?

    <p>An electric force, or EMF</p> Signup and view all the answers

    What is the role of charged ions in chemical action within cells?

    <p>To produce an electromotive force</p> Signup and view all the answers

    What occurs when an atom loses electrons?

    <p>It becomes positively charged.</p> Signup and view all the answers

    In which situation is static electricity most likely to become a concern?

    <p>While fuelling aircraft.</p> Signup and view all the answers

    What phenomenon occurs when a quartz crystal is compressed?

    <p>Piezoelectric effect is produced.</p> Signup and view all the answers

    How does heat influence electron movement in copper?

    <p>Electrons flow toward the cooler end.</p> Signup and view all the answers

    What happens to a metallic substance when it is exposed to light?

    <p>Valence electrons are dislodged.</p> Signup and view all the answers

    Which principle do thermocouples rely on?

    <p>Electron flow due to temperature differences.</p> Signup and view all the answers

    What type of charge is generated on a body when it gains electrons?

    <p>Negative charge.</p> Signup and view all the answers

    What causes a static charge to build up more readily?

    <p>Friction between non-conducting materials.</p> Signup and view all the answers

    Which application uses the principle of the piezoelectric effect?

    <p>Sound detection in microphones.</p> Signup and view all the answers

    How does the surface charge of an aircraft change during movement in the air?

    <p>It builds up huge potential charges.</p> Signup and view all the answers

    What is the role of valence electrons in the structure of an atom?

    <p>They can easily be displaced from their orbits.</p> Signup and view all the answers

    What happens to an atom when a positive charge is applied?

    <p>Its outer electron is drawn away.</p> Signup and view all the answers

    In an electric circuit, what does the term 'electron flow' refer to?

    <p>The directional movement of electrons towards a positively charged source.</p> Signup and view all the answers

    What do free electrons in a conductor represent?

    <p>Electrons that move freely among atoms and contribute to current.</p> Signup and view all the answers

    Why does the hydrogen atom have a neutral overall charge?

    <p>The number of protons equals the number of electrons.</p> Signup and view all the answers

    Which of the following methods does not generate electricity?

    <p>Temperature increase</p> Signup and view all the answers

    What occurs when electrons are displaced from their orbits?

    <p>The atom gains charge leading to current.</p> Signup and view all the answers

    What characterizes a positively charged ion?

    <p>It has more protons than electrons.</p> Signup and view all the answers

    Which type of electron is most easily displaced from its orbit?

    <p>Valence electrons</p> Signup and view all the answers

    What type of electricity generation relies on pressure?

    <p>Hydroelectric generation</p> Signup and view all the answers

    Study Notes

    Atomic Structure of Matter

    • Atoms consist of a nucleus with electrons orbiting around it
    • Hydrogen is the simplest atom, with one proton in its nucleus
    • The number of electrons orbiting the nucleus always equals the number of protons in the nucleus
    • Electrons in outer orbits are attracted to the nucleus by less force than electrons closer to the nucleus
    • Outer electrons can be easily forced from their orbits, becoming free electrons
    • Free electrons create an electric current.

    Electron Theory

    • When a positive charge is applied to an atom, the outer electron is drawn away.
    • The atom now has more protons than electrons and is positively charged.
    • Positively charged atoms attract electrons from surrounding atoms.
    • The flow of electrons toward a positively charged source is called "electron flow."
    • In a conductor connected to a source of electrons, the positive terminal attracts an electron.
    • Electron movement happens within the conductor at the speed of light.
    • An electron entering a conductor instantly forces another electron out from the other end.
    • The flow of electrons performs work, such as powering lights, heating devices, electric motors, and electronics.
    • An imbalance in electrical potential creates an electro-motive force (EMF), which is a driving force for electron flow.

    Potential Difference

    • One electron's potential difference is not practically useful.
    • 6,250,000,000,000,000,000 electrons equal 1 volt.
    • When a switch is turned on, electrons flow from one potential difference to another.
    • The rate of electron flow is proportional to the potential difference.

    Types of electricity

    • Two main types of electricity are current and static electricity.
    • Current electricity involves electrons moving through a circuit and performing work.
    • Static electricity is more of a nuisance.

    Voltage Produced by Friction

    • When two materials are rubbed together, electrons are transferred from one material to the other.
    • The material losing electrons becomes electrically positive, while the material gaining electrons becomes electrically negative.
    • Good conductors equalize charges quickly, while poor conductors allow electrostatic charge to build up.
    • Static charges are more readily created between non-conducting materials.

    Voltage Produced by Pressure

    • Compressing a quartz crystal creates charges on opposite surfaces.
    • This phenomenon is known as the piezoelectric effect.
    • The piezoelectric effect can convert mechanical energy into electrical energy.
    • Microwaves and barbecue lighters utilize this principle.

    Voltage Produced by Heat

    • When copper is heated, valence electrons move towards the cooler end.
    • In iron, electrons move towards the hotter end.
    • Electron flow through the hot junction is proportionate to the intensity of heat.
    • Thermocouples measure electron flow to indicate temperature.

    Voltage Produced by Light

    • Light has energy, similar to any moving force.
    • Some metallic substances are sensitive to light.
    • Light striking these surfaces dislodges valence electrons, creating a positive charge on the metal.
    • The resulting EMF is known as photoelectric voltage.

    Voltage Produced by Chemical Action

    • Two dissimilar metallic materials immersed in a solution create a chemical reaction.
    • One material has a greater chemical action, leading to the formation of charged ions and the production of EMF.
    • Wet cells contain liquid electrolytes and must be kept upright.
    • Dry cells have electrolytes mixed into a paste.

    Voltage Produced by Magnetism and Motion

    • To generate voltage through magnetism, three conditions must exist:
      • A conductor where voltage will be produced
      • A magnetic field near the conductor
      • Relative motion between the field and conductor
    • The conductor must move to cut through magnetic lines of force, or the magnetic field must move across the conductor.
    • This motion forces electrons in a specific direction, creating electric force or voltage.
    • Electromagnetic induction is the most common form of power generation.
    • Aircraft generators and alternators, as well as atomic, hydro-electric, and fossil fuel power plants, utilize this principle.

    Voltage Produced by Magnetism - Summary

    • Spinning a loop of wire in a magnetic field creates EMF.
    • Relative motion between the conductor and magnetic flux lines is essential.

    Generation of Electricity

    • Light, heat, friction, pressure, chemical action, and magnetism and motion are all methods to produce electricity.

    Production of Electricity by Different Methods

    • Friction: Rubbing materials together
    • Pressure: Using the piezoelectric effect of materials (quartz)
    • Heat: Heating materials with different responses to temperature changes
    • Light: Using the photoelectric effect where light dislodges electrons from metals
    • Chemical Action: Creating chemical reactions between dissimilar metals
    • Magnetism and Motion: Using relative motion between a conductor and a magnetic field.

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    Description

    This quiz covers the fundamental concepts of atomic structure and the behavior of electrons, including the details about the nucleus, protons, and electron flow. It explores how atoms interact with electric charges and the implications of free electrons in conductors. Test your understanding of these core scientific principles!

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