Examstyle Questions: Electromagnetic Induction

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)

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 outline and marking scheme for question:

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)

a) Area per second = wing span x speed (1 Mark)
= 44.8 x 250
= 1.12 x 10^{4 }m^{2} 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)