Electrical Fundamentals: Resistance and Factors
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Questions and Answers

According to the electron theory, which direction does the current flow?

  • From a point of high potential to a point of low potential
  • From the negative terminal to the positive terminal (correct)
  • From a point of low pressure to a point of high pressure
  • From the positive terminal to the negative terminal

    • What is the unit for measuring the rate of transfer of charge?

  • Ampere
  • Ohm
  • Volt
  • Coulomb per second (correct)

    • What is the abbreviation for ampere?

  • A
  • I
  • Amp (correct)
  • V

    • If 1 C flows through a circuit each second, what is the current?

    <p>One ampere</p> Signup and view all the answers

    What does I = 3 A represent in relation to electric current?

    <p>A current of three amps</p> Signup and view all the answers

    What did Edison discover when he connected the filament battery and allowed the filament to heat until it glowed?

    <p>The ammeter in the filament-plate circuit deflected and remained deflected</p> Signup and view all the answers

    What was the direction of the electrical current flowing in the filament-plate circuit according to Edison's reasoning?

    <p>From the filament to the plate</p> Signup and view all the answers

    Why did Edison place a positive charge on the plate in the filament-plate circuit?

    <p>To attract electrons from the filament</p> Signup and view all the answers

    What is the actual application of a basic law mentioned in the text?

    <p>Opposite charges attract</p> Signup and view all the answers

    What was Edison's reaction to his discovery of electron flow across the space between filament and plate?

    <p>He did little with this discovery because it did not eliminate the soot problem</p> Signup and view all the answers

    What is the main reason carbon is used in rubbing connections with commutators or slip rings?

    <p>Its self-lubricating quality</p> Signup and view all the answers

    What is the overall charge of an atom that gains an electron?

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

    In a liquid, which type of atoms are ionized to form ions?

    <p>Molecules</p> Signup and view all the answers

    What direction do negatively charged ions move in a liquid?

    <p>Towards the cathode</p> Signup and view all the answers

    What is the main significance of carbon as a conductor compared to other non-metal solids?

    <p>It has high resistance compared to metals</p> Signup and view all the answers

    What is the relationship between voltage and potential difference?

    <p>Voltage and potential difference can be positive or negative, depending on the point of reference.</p> Signup and view all the answers

    How does resistance affect the current in a circuit with steady EMF?

    <p>Halving the resistance doubles the current.</p> Signup and view all the answers

    What is the unit of electrical resistance?

    <p>Ohm</p> Signup and view all the answers

    How does resistance change with the length of a conductor?

    <p>Resistance increases with increasing length of a conductor.</p> Signup and view all the answers

    What happens to resistance when cross-sectional area of a conductor increases?

    <p>Resistance decreases</p> Signup and view all the answers

    According to Ohm's law, what is the relationship between voltage, current, and resistance?

    <p>V = I/R</p> Signup and view all the answers

    What factors control the resistance of an object like a wire conductor?

    <p>Material, length, cross-sectional area, temperature</p> Signup and view all the answers

    In which scenario does a material offer more resistance to the flow of electric current?

    <p>When it is hotter</p> Signup and view all the answers

    What is the reciprocal of resistance in an electric circuit?

    <p>Conductance</p> Signup and view all the answers

    What happens when ions reach the electrodes in an electrolyte solution?

    <p>They give or receive electrons, contributing to the electron transfer of charge through the solid conducting circuit.</p> Signup and view all the answers

    What causes gases to become conductors when ionized?

    <p>High electrical potentials dislodge electrons from the atoms or molecules of the gas.</p> Signup and view all the answers

    In which conditions does ionisation occur?

    <p>In the air path of a lightning discharge, spark plugs in piston engines, and fluorescent lamps.</p> Signup and view all the answers

    What did Thomas Edison discover in his quest to keep soot from clouding his incandescent light bulb?

    <p>The principle of thermionic emission.</p> Signup and view all the answers

    How does thermionic emission relate to incandescent light bulbs?

    <p>It involves the emission of electrons from a heated filament, contributing to the production of light in incandescent bulbs.</p> Signup and view all the answers

    What type of compound is acetic acid based on its ability to conduct electricity?

    <p>Weak electrolyte</p> Signup and view all the answers

    Which of the following best describes the molecular structure of compounds with strong conductivity?

    <p>Dissociate completely into charged atoms or molecules when dissolved in water</p> Signup and view all the answers

    What type of materials are commonly used as conductors due to their single valence electron?

    <p>Metals</p> Signup and view all the answers

    What happens to ions when they reach the electrodes in an electrolyte solution?

    <p>They lose their charge and become neutral atoms</p> Signup and view all the answers

    Which type of compound dissociates into positively charged sodium and negatively charged chlorine ions in water?

    <p>Table salt</p> Signup and view all the answers

    What is the main component of vinegar that is a poor conductor of electricity?

    <p>Acetic acid</p> Signup and view all the answers

    Which of the following compounds is an example of a weak electrolyte?

    <p><strong>Acetic acid</strong></p> Signup and view all the answers

    What determines the conductivity of compounds with strong conductivity?

    <p><strong>Concentration of ions</strong></p> Signup and view all the answers

    Insulators are characterized by atoms that have a single valence electron very loosely bound to the atom.

    <p><strong>False</strong></p> Signup and view all the answers

    Gold is commonly used as a semiconductor due to its molecular structure.

    <p><strong>False</strong></p> Signup and view all the answers

    Study Notes

    Electric Current and Flow

    • Electric current flows from negative to positive.
    • The unit for measuring the rate of transfer of charge is Coulomb (C).
    • The abbreviation for ampere is A.
    • If 1 C flows through a circuit each second, the current is 1 A.
    • I = 3 A represents a current of 3 amperes.

    Edison's Discovery

    • Edison discovered that when he connected the filament battery and allowed the filament to heat until it glowed, it produced a flow of electrons across the space between the filament and plate.
    • According to Edison's reasoning, the electrical current flowed from the negative filament to the positive plate.
    • Edison placed a positive charge on the plate to create a flow of electrons.

    Electric Conduction

    • Carbon is used in rubbing connections with commutators or slip rings due to its unique properties.
    • When an atom gains an electron, it becomes negatively charged.
    • In a liquid, atoms are ionized to form ions.
    • Negatively charged ions move towards the positive electrode in a liquid.
    • Carbon's conductivity is significant compared to other non-metal solids due to its unique properties.

    Voltage and Resistance

    • Voltage and potential difference are equivalent.
    • Resistance affects the current in a circuit with steady EMF, reducing it.
    • The unit of electrical resistance is Ohm (Ω).
    • Resistance increases with the length of a conductor and decreases with the cross-sectional area of a conductor.
    • Ohm's law states that voltage is equal to the product of current and resistance.
    • Factors controlling the resistance of an object like a wire conductor include its length, cross-sectional area, and material properties.

    Ionization and Conductivity

    • When ions reach the electrodes in an electrolyte solution, they are neutralized.
    • Gases become conductors when ionized.
    • Ionization occurs under certain conditions, such as high temperatures.
    • Thomas Edison discovered thermionic emission in his quest to keep soot from clouding his incandescent light bulb.
    • Thermionic emission relates to incandescent light bulbs, where heat causes electrons to be emitted.
    • Acetic acid is a poor conductor of electricity.
    • Compounds with strong conductivity have a molecular structure that allows for easy movement of electrons.
    • Materials with single valence electrons, such as copper, are commonly used as conductors.
    • Ions are neutralized when they reach the electrodes in an electrolyte solution.
    • Sodium chloride dissociates into positively charged sodium and negatively charged chlorine ions in water.
    • The main component of vinegar that is a poor conductor of electricity is acetic acid.
    • Vinegar is an example of a weak electrolyte.
    • The conductivity of compounds with strong conductivity is determined by their molecular structure.

    Insulators and Semiconductors

    • Insulators are characterized by atoms that have a single valence electron very tightly bound to the atom.
    • Gold is not commonly used as a semiconductor due to its molecular structure.

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    Description

    Test your knowledge of electrical fundamentals with a focus on resistance and the factors that control it. This quiz covers the symbol for resistance, factors affecting resistance, and the concept of electrical conductors.

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