OCR A Level Physics 4.1 Charge & Current
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Questions and Answers

In an electrical circuit, where should an ammeter be connected?

  • In series (correct)
  • In parallel
  • It doesn't matter where the ammeter is connected
  • In series or parallel depending on the situation
  • Which component allows current to flow in only one direction in an electrical circuit?

  • Voltmeter
  • Diode (correct)
  • Ammeter
  • Lamp
  • What is the correct direction of current flow in an electrical circuit?

  • From positive to negative terminal (correct)
  • From the switch to the load
  • From the load to the switch
  • From negative to positive terminal
  • Which of the following is used to measure voltage in an electrical circuit?

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

    What type of component must be used for current to flow in only one direction?

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

    When drawing a circuit diagram, why is it important to make the circuit symbols neat and clear?

    <p>To ensure full marks are awarded</p> Signup and view all the answers

    What is the purpose of an ammeter in a circuit?

    <p>Measure the current</p> Signup and view all the answers

    In which way are an ammeter and voltmeter typically connected in a circuit?

    <p>Ammeter in series, voltmeter in parallel</p> Signup and view all the answers

    Why are the resistances of ammeters and voltmeters considered negligible in exam questions?

    <p>To simplify calculations</p> Signup and view all the answers

    What is an essential component required for electric circuit diagrams to work effectively?

    <p>Energy source</p> Signup and view all the answers

    Which of the following is necessary for electrons to flow in a complete loop in a circuit?

    <p>Open path</p> Signup and view all the answers

    What is the role of circuit symbols in interpreting electric circuit diagrams?

    <p>Simplify and standardize circuit representation</p> Signup and view all the answers

    What is the function of a light-emitting diode (LED)?

    <p>Emits light when a current passes through it</p> Signup and view all the answers

    Which component of a circuit limits the flow of current?

    <p>Fixed resistor</p> Signup and view all the answers

    What happens to the resistance of a thermistor as its temperature increases?

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

    Which component is used to convert AC (Alternating Current) to DC (Direct Current)?

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

    In which direction does a diode allow current flow?

    <p>One direction only</p> Signup and view all the answers

    What type of component is often used in dimmer switches and volume controls?

    <p>Variable resistor</p> Signup and view all the answers

    In which direction does conventional current flow in a metal?

    <p>From positive to negative</p> Signup and view all the answers

    What is the unit used to measure electric current?

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

    When two oppositely charged conductors are connected together, what will happen?

    <p>Charge will flow between the conductors causing a current</p> Signup and view all the answers

    How should an ammeter be connected in a circuit to measure current?

    <p>In series</p> Signup and view all the answers

    Which component is used to measure current in a circuit?

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

    What is the relationship between charge, current, and time according to the given equation?

    <p>$I = \frac{ΔQ}{Δt}$</p> Signup and view all the answers

    What is electric current defined as?

    <p>Rate of flow of charge carriers</p> Signup and view all the answers

    In metals, which component is responsible for creating the flow of charge?

    <p>Free (delocalised) electrons</p> Signup and view all the answers

    What makes metals good conductors of electricity?

    <p>Presence of conduction electrons</p> Signup and view all the answers

    What type of ion is an anion?

    <p>Negative ion (gained an electron)</p> Signup and view all the answers

    Which components create current flow in electrolytes?

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

    What do the free (delocalised) electrons do when one side of the metal is attached to a negative terminal and the other to a positive terminal?

    <p>Drift slowly through the metal creating a current</p> Signup and view all the answers

    Which component is always connected in series in an electrical circuit?

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

    In which direction does current flow in a metal conductor?

    <p>From the positive to the negative terminal</p> Signup and view all the answers

    Which type of diode allows current to flow in only one direction?

    <p>Forward-biased diode</p> Signup and view all the answers

    What is the main function of an ammeter in an electrical circuit?

    <p>Measure the current</p> Signup and view all the answers

    What happens to the resistance of a thermistor as its temperature increases?

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

    Why are the resistances of ammeters and voltmeters considered negligible in exam questions?

    <p>To simplify calculations for students</p> Signup and view all the answers

    Which diagram would correctly represent a circuit with a forward-biased diode allowing current flow?

    <p>Circuit B</p> Signup and view all the answers

    In which type of material do free (delocalized) electrons allow electric current to flow most easily?

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

    What is the purpose of drawing and interpreting circuit diagrams using symbols in the context of electricity?

    <p>To convey complex electrical circuits in a simple way</p> Signup and view all the answers

    Which component is essential for creating a closed path or complete circuit in an electrical system?

    <p>Power source</p> Signup and view all the answers

    What is the unit for measuring electric current?

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

    Which direction does conventional current flow in a metal?

    <p>From positive to negative</p> Signup and view all the answers

    In which type of material do free electrons allow for the flow of charge?

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

    What happens when charge flows between two oppositely charged conductors?

    <p>A current is induced</p> Signup and view all the answers

    Where should an ammeter be connected in an electrical circuit to measure current?

    <p>In series with the load</p> Signup and view all the answers

    What is the primary function of a light-emitting diode (LED) in an electrical circuit?

    <p>To emit light when a current passes through</p> Signup and view all the answers

    Which component in a circuit is designed to limit the flow of current?

    <p>Variable resistor</p> Signup and view all the answers

    What effect does an increase in light intensity have on the resistance of a Light-dependent resistor (LDR)?

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

    In a circuit diagram, what does a diode symbol represent?

    <p>Component that allows current in one direction only</p> Signup and view all the answers

    What is the purpose of a variable resistor in an electrical circuit?

    <p>To change its resistance value</p> Signup and view all the answers

    In metals like copper and titanium, what is responsible for the flow of charge?

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

    What type of ion is formed when an atom gains an electron?

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

    What makes metals like copper good conductors of electricity?

    <p>Presence of conduction electrons</p> Signup and view all the answers

    What happens to ions in electrolytes that have lost or gained an electron?

    <p>They become cations or anions</p> Signup and view all the answers

    Which type of ion is a positive ion that has lost an electron?

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

    What is the main difference between an electrolyte and a metal conductor in terms of charge carriers?

    <p>An electrolyte carries cations and anions, while a metal conductor carries electrons.</p> Signup and view all the answers

    Which of the following statements best describes the flow of current in terms of conventional current and electron flow?

    <p>Conventional current flows from positive to negative, opposite to the flow of electrons.</p> Signup and view all the answers

    In an electrical circuit, what is the function of an ammeter?

    <p>Measure the flow of current in the circuit.</p> Signup and view all the answers

    When drawing circuit diagrams, what is the primary purpose of using neat and clear circuit symbols?

    <p>To ensure accurate representation of components and connections.</p> Signup and view all the answers

    What role do anions and cations play in the conductivity of an electrolyte?

    <p>Cations are attracted to the cathode while anions are attracted to the anode.</p> Signup and view all the answers

    In a series circuit, what happens to the current as it passes through different points?

    <p>It remains the same at each point</p> Signup and view all the answers

    Which law applies at each junction in a parallel circuit?

    <p>Kirchhoff’s first law</p> Signup and view all the answers

    What is the main difference between the current flow in a series circuit and a parallel circuit?

    <p>Current divides at junctions in a series circuit</p> Signup and view all the answers

    What should you do to avoid confusion in complex circuits regarding the direction of currents entering and leaving junctions?

    <p>Draw arrows indicating current flow at each junction</p> Signup and view all the answers

    Why is it important to draw clear and neat circuit symbols when creating circuit diagrams?

    <p>To ensure proper interpretation of the circuit diagram</p> Signup and view all the answers

    What role do junctions play in electric circuits?

    <p>They divide current in series circuits</p> Signup and view all the answers

    How does the current split at junctions in a parallel circuit?

    <p>It remains constant at each branch</p> Signup and view all the answers

    What is the purpose of drawing arrows indicating current flow in circuit diagrams?

    <p>To show the direction of current flow at each junction</p> Signup and view all the answers

    What is the key difference between a series and a parallel circuit in terms of current division?

    <p>In a series circuit, current values across different components are equal, while in a parallel circuit, each branch can have different currents.</p> Signup and view all the answers

    What action can help clarify the direction of currents entering and leaving junctions in complex circuits?

    <p>Drawing arrows indicating current flow at each junction</p> Signup and view all the answers

    Study Notes

    Electric Circuits and Components

    • A circuit can be open or closed using a switch, and for a circuit to be connected, the switch must be closed.
    • Electrical components can act as sensors, measure values, or transfer energy to other forms.
    • These components must be drawn with the correct circuit symbol.

    Circuit Symbols and Diagrams

    • Circuit symbols are used to represent components in circuit diagrams.
    • The most common symbols are:
      • Cell/battery/D.C. supply: provides a source of e.m.f.
      • Switch: turns the circuit on (closed) or off (open)
      • Fixed resistor: limits the flow of current and has a fixed resistance
      • Variable resistor: has a slider to change its resistance, often used in dimmer switches and volume controls
      • Thermistor: resistance depends on temperature, decreasing as temperature increases
      • Light-dependent resistor (LDR): resistance depends on light intensity, decreasing as light intensity increases
      • Diode: allows current to flow in one direction, used to convert AC to DC current
      • Light-emitting diode (LED): equivalent to a diode and emits light when a current passes through it

    Electric Current and Electron Flow

    • Electric current is the rate of flow of positive charge carriers, defined as the movement of electrons in metals or ions in electrolytes.
    • In metals, electrons are the charge carriers, and they flow from the negative terminal to the positive terminal.
    • Ions in electrolytes are either anions (negative) or cations (positive), and they flow towards the opposite terminal.

    Measuring Current and Voltage

    • Ammeters are used to measure current in a circuit and are connected in series with the part of the circuit being measured.
    • Voltmeters are used to measure the potential difference of an electrical component and are connected in parallel with the component.

    Circuit Diagrams

    • Circuit diagrams require:
      • An energy source (e.g. cell, battery, or power supply)
      • A closed path or complete circuit for electrons to flow
      • Electrical components, drawn with correct circuit symbols
    • When drawing circuit diagrams, use straight lines and a ruler to make it neat and clear, and ensure circuit symbols are accurate.

    Exam Tips

    • Make sure to recognize and draw all circuit symbols correctly.
    • When drawing circuit diagrams, draw arrows to indicate current flow (from positive to negative) at each junction to help with complex circuits.
    • Ensure wires are drawn as straight lines with a ruler and make the diagram as neat as possible, especially the circuit symbols.

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    Description

    Test your knowledge on topics such as Electric Current, Kirchhoff's First Law, Conductors, Semiconductors & Insulators, and Circuit Symbols & Diagrams in OCR A Level Physics 4.1 Charge & Current. Get ready for your exams with this quiz!

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