Exam-style Questions: Electromagnetic Induction

  1. The magnetic flux linkage of a coil wire increases steadily by 90 mWb in a time of 450 μs.

    a) Show that the rate of change of magnetic flux linkage is 200 Wb s-1.

    (2 Marks)

    b) State the emf induced across the coil by the rate of change og magnetic flux linkage.

    emf = ......................... V

    (1 Mark)

    (Marks available: 3)

  2. The wing span of an Airbus A300 is 44.8 m.

    a) What area is swept out per second when the plane is in level flight at 250 m s-1?

    (2 Marks)

    b) If the vertical component of the Earth's magnetic field is 50 μT, what potential difference is induced between the tips of the Airbus wings?

    (2 Marks)

    (Marks available: 4)

Answer

Answer outline and marking scheme for question:

  1. a) 90 mWb = 90 x 10-3 Wb, 450 μs = 450 x 10-6 s

    90 x 10-3/450 x 10-6 ( = 200 Wb s-1)

    (2 Marks)

    b) 200 V

    (1 Mark)

    (Marks available: 3)

  2. a) Area per second = wing span x speed (1 Mark)

    = 44.8 x 250

    = 1.12 x 104 m2 s-1 (1 Mark)

    (2 Marks)

    b) Magnetic flux = B x A

    = 50 x 10-6 x 1.12 x 104 wb (1 Mark)

    emf = dΦ = 0.56 volts (1 Mark)
    dt

    (2 Marks)

    (Marks available: 4)