Physics Chapter on Electric Current
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Questions and Answers

What is the primary function of an electric fuse?

  • To protect electrical appliances and prevent fires. (correct)
  • To decrease the voltage in a circuit.
  • To convert electrical energy into mechanical energy.
  • To increase the flow of electricity in a circuit.

    • What is the principle on which an electric fuse operates?

  • The heating effect of electric current. (correct)
  • The electrostatic effect of electric current.
  • The magnetic effect of electric current.
  • The chemical effect of electric current.

    • Boojho made an electromagnet with 50 turns of wire, while Paheli made one with 100 turns. Which electromagnet is stronger?

  • Boojho's electromagnet is stronger.
  • Paheli's electromagnet is stronger. (correct)
  • Both electromagnets are equally strong.
  • The strength of the electromagnet is determined by the type of wire used.

    • Why are multiple cells connected together called a battery?

    <p>Because they are interconnected internally and provide a collective output. (A)</p> Signup and view all the answers

    Which of the following is a precaution to be taken while using electricity in homes?

    <p>Using only electric cells for all experiments. (D)</p> Signup and view all the answers

    In an open circuit, the switch is in the ______ position, and the bulb ______.

    <p>OFF, does not glow. (A)</p> Signup and view all the answers

    Which of the following is a characteristic of a closed circuit?

    <p>The circuit is complete, and current can flow. (D)</p> Signup and view all the answers

    What is the primary factor that determines whether a magnetic field is created around a conductor?

    <p>The flow of electric current through the conductor. (A)</p> Signup and view all the answers

    Which of the following is NOT a precaution related to using electricity in homes?

    <p>Connect as many appliances as possible to a single socket. (B)</p> Signup and view all the answers

    Which of the following is a potential consequence of experimenting with the electrical supply from the mains?

    <p>A dangerous electric shock. (D)</p> Signup and view all the answers

    Which of the following characteristic is not suitable for a fuse wire?

    <p>Thick and short (B)</p> Signup and view all the answers

    The magnetic effect of electric current was discovered by?

    <p>Oersted (B)</p> Signup and view all the answers

    Continuous flow of electric current through a circuit requires?

    <p>All of these (B)</p> Signup and view all the answers

    Which of the following does not work on the heating effect of electric current?

    <p>Miniature circuit breaker (D)</p> Signup and view all the answers

    The strength of an electromagnet can be increased by?

    <p>Increasing the number of coils (A)</p> Signup and view all the answers

    What causes the hammer in an electric bell to continue striking the gong repeatedly?

    <p>Repetition of breaking and completion of the circuit (A)</p> Signup and view all the answers

    How does increasing the current affect the strength of an electromagnet?

    <p>It increases strength regardless of the number of turns (D)</p> Signup and view all the answers

    What happens when a fuse blows in an electrical circuit?

    <p>The circuit is broken and prevented from damage (B)</p> Signup and view all the answers

    Which statement is true regarding the deflection of a magnetic compass near a current-carrying wire?

    <p>The compass deflects only when the current is flowing (A)</p> Signup and view all the answers

    What is the primary difference between cells in series and cells in parallel when connected in a circuit?

    <p>Cells in series increase voltage; cells in parallel increase current (B)</p> Signup and view all the answers

    Flashcards

    Fuse Wire Characteristics

    A fuse wire should be thin, short, and have a low melting point.

    Oersted's Discovery

    Hans Christian Oersted discovered the magnetic effect of electric current.

    Continuous Current Requirement

    A continuous flow of electric current requires a source, conducting material, and a closed circuit.

    Electromagnet Strength

    The strength of an electromagnet is increased by adding more coils or increasing the current.

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    Safety in Electric Circuits

    Using electric cells reduces risks when conducting experiments with electric circuits.

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    Electric Bell Function

    A hammer strikes the gong when current turns the coil into an electromagnet.

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    Continuing Strikes in Bell

    The hammer continues striking due to repeated circuit breaking and completing.

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    Circuit Diagram Representation

    An electric circuit is represented by a diagram showing components like switches.

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    Cells in Series vs. Parallel

    In series, cells connect in a row; in parallel, they connect beside one another.

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    Magnetic effect of electric current

    A phenomenon where electric current creates a magnetic field around a conductor.

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    Electric fuse

    A safety device that protects electrical circuits by breaking the circuit if current is too high.

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    Heating effect of electric current

    The principle that current generates heat, used in electric fuses to break the circuit.

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    Difference between open circuit and closed circuit

    An open circuit is incomplete and doesn’t allow current, while a closed circuit is complete and allows current to flow.

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    Open circuit

    A circuit that is not complete, preventing electric current from passing through.

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    Closed circuit

    A complete circuit that allows electric current to flow, lighting the bulb.

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    Batteries vs Cells

    Batteries are collections of cells; they function collectively as a power source.

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    Safety precautions with electricity

    Important measures to avoid electric shocks or accidents with electrical devices.

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    Electromagnet comparison

    An electromagnet made with more turns (like Paheli's) is stronger and attracts more pins than one with fewer turns.

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    Study Notes

    Objective Type Questions

    • Fuse Wire Characteristics: A fuse wire should be thin and short, with a low melting point, and a higher resistance than the rest of the wiring.

    • Magnetic Effect of Electric Current: Oersted discovered the magnetic effect of electric current.

    • Continuous Current Flow: A continuous electric current flow requires a source of current, a conducting material, and a closed circuit.

    • Heating Effect of Electric Current: An electric bulb, miniature circuit breaker, and electric fuse all work on the heating effect of electric current; an immersion rod doesn't.

    • Electromagnet Strength: Increasing the number of coils will increase the strength of an electromagnet; decreasing the current strength will decrease the strength.

    • Electric Circuit Components: The diagram represents a battery/cell in a circuit for electric current (from context).

    Very Short Answer Type Questions (2 Marks)

    • Series vs. Parallel Cells: Series cells connect the positive terminal of one cell to the negative of the next, while parallel cells connect similar terminals together.

    • Magnetic Effect of Current: The continuous flow of current through a conductor creates a magnetic field.

    • Electric Fuse: A safety device that protects electrical appliances by melting when current exceeds a safe limit; it works due to the heating effect.

    • Electromagnet Strength: A larger number of turns of wire on the electromagnet results in a stronger electromagnet, attracting more pins.

    Short Answer Type Questions (3 Marks)

    • Battery vs. Cells: A battery is a collection of cells in a configuration where connections are internal rather than external.

    • Safety Precautions in Electrical Use: Never touch a hot/lighted bulb connected to mains/generator/inverter, and use only batteries/cells in experiments.

    • Open vs. Closed Circuits: An open circuit has a break and does not allow current to flow; a closed circuit is complete and lets current pass.

    • Low Melting Point Fuse Wire: Low melting point is crucial to the fuse wire's ability to break the circuit/stop electrical flow when current is too high. This prevents further damage to the circuit.

    • Excessive House Current: Causes of excessive house current include direct wire contact and connecting too many devices to a single socket (overloading).

    Long Answer Type Questions (5 Marks)

    • Electromagnet Uses: Loudspeakers, electrical bells, cranes, measuring instruments (telephones, refrigerators, generators), and separating magnetics materials from junk.

    • Electric Circuit: An interrupted path where electrical current flows, typically containing electrical components (sources, wires, etc.).

    • Electric Bell Operation: An electromagnet attracting the soft metal armature causes it to strike a gong; the release and repetition of this process due to the spring mechanism creates the ringing sound.

    Source-Based/Case Study Questions

    • Incandescent vs. Efficient Bulbs: Incandescent bulbs waste energy as heat; efficient bulbs, like LEDs, use less energy to produce the same light output.

    • Heating Effect of Current: Electric current passing through a wire produces heat.

    • Disposal of Damaged Fluorescent Bulbs: Damaged fluorescent and CFL bulbs should be disposed of safely as they contain mercury vapour, which is toxic.

    • Factors Affecting Wire Heating: The heat produced in a wire depends on the type of material, its length, thickness, and the current flowing through it.

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