# 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 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)