Physics: Electromagnetic Flux Concepts
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Questions and Answers

What can be done to obtain a large deflection of the galvanometer?

  • Slowly move the arrangement towards the test coil.
  • Connect the coil to a powerful battery. (correct)
  • Change the direction of the current.
  • Use an aluminum rod inside the coil.

    • Which method can demonstrate the presence of an induced current without using a galvanometer?

  • Using a digital multimeter to check resistance.
  • Connecting another coil wired to a speaker.
  • Observing the glow of a small bulb. (correct)
  • Measuring the voltage drop across a resistor.

    • What is the outcome of rotating a coil in a magnetic field?

  • It permanently magnetizes the coil.
  • It changes the shape of the magnetic field.
  • It generates heat in the coil.
  • It induces an electromotive force (emf). (correct)

    • How does changing the shape of the coil affect the induced emf?

    <p>It alters the area within the magnetic field.</p> Signup and view all the answers

    In the context of experimental physics, what is primarily highlighted by Michael Faraday's work?

    <p>The value of innovative skills in experiments.</p> Signup and view all the answers

    What is the resistance of the square loop mentioned in the content?

    <p>0.5 ohm</p> Signup and view all the answers

    What happens to the current when a soft iron rod is placed inside the coil?

    <p>It increases the current flow.</p> Signup and view all the answers

    What is indicated by the angle $\theta$ between magnetic field $B$ and area $A$?

    <p>The orientation of magnetic field lines.</p> Signup and view all the answers

    What phenomenon is responsible for the deflection observed in the galvanometer during the experiments?

    <p>Relative motion between the coils</p> Signup and view all the answers

    What happens to the galvanometer's deflection when coil C2 moves away from coil C1?

    <p>It deflects in the opposite direction</p> Signup and view all the answers

    What is observed when the tapping key K is pressed in Experiment 6.3?

    <p>Momentary deflection followed by no deflection</p> Signup and view all the answers

    What occurs when the tapping key K is held down continuously?

    <p>No deflection is observed</p> Signup and view all the answers

    In Experiment 6.2, what role does coil C2 play in inducing current in coil C1?

    <p>It generates a steady magnetic field</p> Signup and view all the answers

    What is the relationship between movement and induced current as described in the experiments?

    <p>Relative motion between coils is essential for induction</p> Signup and view all the answers

    What happens to the galvanometer's pointer when the key is released after being pressed?

    <p>It deflects momentarily in the opposite direction</p> Signup and view all the answers

    What is the composition of coils and loops mentioned in the experiments?

    <p>They are made of conducting material with insulating coating</p> Signup and view all the answers

    What does the negative sign in the equation for induced emf indicate?

    <p>The direction of current in a closed loop</p> Signup and view all the answers

    How can the induced emf be increased when using a closed coil?

    <p>By increasing the magnetic flux density</p> Signup and view all the answers

    In the context of a coil with N turns, what factor affects the total induced emf the most?

    <p>The number of turns N in the coil</p> Signup and view all the answers

    Which of the following parameters can be varied to change the magnetic flux?

    <p>Magnetic flux density B, area A, or charge q</p> Signup and view all the answers

    Which scientist is credited with the discovery of electromagnetic induction?

    <p>Michael Faraday</p> Signup and view all the answers

    What is the relationship between magnetic flux and the induced emf in a coil?

    <p>Induced emf is directly proportional to the rate of change of magnetic flux</p> Signup and view all the answers

    What does Eq. (6.4) represent in the context of electromagnetic induction?

    <p>Induced emf for a coil with N turns</p> Signup and view all the answers

    Which term is NOT relevant when discussing changing magnetic flux?

    <p>Electric potential (V)</p> Signup and view all the answers

    What does the symbol 'ω' represent in the equation for induced emf?

    <p>Angular velocity</p> Signup and view all the answers

    If the number of turns in a coil increases, how does this affect the induced emf?

    <p>Induced emf increases</p> Signup and view all the answers

    What is the SI unit of inductance?

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

    What is the induced emf calculated using Method I?

    <p>157 V</p> Signup and view all the answers

    In a closely wound coil, how is flux linkage defined?

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

    What type of relationship does inductance have with the geometry of the coil?

    <p>It is directly proportional</p> Signup and view all the answers

    Which variable represents the angular velocity in the expression of induced emf?

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

    What is the formula for the area of the sector OPQ as derived in the content?

    <p>$\frac{1}{2}\pi R^2\theta$</p> Signup and view all the answers

    Which of the following describes mutual inductance?

    <p>Flux change in one coil induces an emf in another</p> Signup and view all the answers

    What is the relationship between the velocity v and angular velocity ω in the context of induced emf?

    <p>$v = R \omega$</p> Signup and view all the answers

    What happens to the induced emf when the magnetic flux through a coil is held constant while the current changes?

    <p>Induced emf does not change</p> Signup and view all the answers

    How is the rate of change of area related to induced emf?

    <p>It directly impacts the size of the emf.</p> Signup and view all the answers

    The dimensions of inductance can be expressed as?

    <p>[M L2 T –2 A–2]</p> Signup and view all the answers

    Given that HE = 0.4 G, what is the equivalent value in teslas?

    <p>0.04 T</p> Signup and view all the answers

    What is the value of the radius R used in the example with metallic spokes?

    <p>0.5 m</p> Signup and view all the answers

    What is the angular velocity of the wheel if it rotates at 120 rev/min?

    <p>$12 \pi$ rad/s</p> Signup and view all the answers

    Study Notes

    Electromagnetic Induction

    • Electric flux can be altered by an electric generator or transformer through actions like changing coil shapes, moving coils within magnetic fields, or rotating coils.
    • An electromotive force (emf) is induced in coils as the angle between the magnetic field (B) and the area (A) changes.

    Faraday's Experiments

    • To achieve a large deflection of a galvanometer, strategies include inserting a soft iron rod into the coil, connecting to a strong battery, or moving the entire setup quickly.
    • Induced current can be demonstrated without a galvanometer by using a small bulb which lights up due to relative motion between coils.

    Faraday's Law

    • The emf induced in a coil is calculated mathematically:
      • ε = -dΦB/dt
      • The negative sign indicates the direction of the induced current.
    • For multi-turn coils, the formula for total emf becomes:
      • ε = -N(dΦB/dt) where N is the number of turns.

    Flux Variation

    • Flux (ΦB) through a coil can be varied by changing magnetic field strength (B), coil area (A), or the angle (q) between B and A.
    • The induced emf can be increased by increasing the number of turns in a coil.

    Induced emf Calculation

    • For a rotating loop in a magnetic field, formulas based on geometry and motion are used to calculate the emf induced.
    • Example: A wheel with spokes rotating in a magnetic field can induce an emf calculated using:
      • Induced emf = (1/2)ωBR² where ω is angular velocity, B is magnetic field strength, and R is radius.

    Inductance

    • Inductance is defined as the property of a coil where the induced flux through it is proportional to the current flowing through it (ΦB ∝ I).
    • The relationship can be expressed as:
      • NΦB ∝ I, with inductance being a geometric and material property of the coil.
    • Inductance is measured in henries (H) and represents the current-carrying capacity of the coil linked to magnetic field effects.

    Mutual Inductance

    • Mutual inductance occurs when a current through one coil induces a magnetic flux in a nearby coil, represented as Φ1 for the first coil influenced by the current I2 through the second coil.
    • Key parameters include the geometrical dimensions of the coils and the number of turns per unit length.

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    Description

    This quiz explores the concepts of electromagnetic flux influenced by electric generators and transformers. It examines how the shape of a coil and its position in a magnetic field can alter the flux. Test your understanding of these fundamental principles in electromagnetism.

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