A coil with 35 circular turns, each of diameter 80 mm, is placed in a uniform magnetic field of flux density 120 mT120\text{ mT}120 mT. Initially, the plane of the coil is perpendicular to the magnetic field lines. The coil is rotated by 90∘ 90^\circ\,90∘ in a time of 0.15 s so that its plane becomes parallel to the field lines. Assuming the rate of change of flux linkage is constant, what is the magnitude of the average emf induced in the coil?
zero
14 mV14\text{ mV}14 mV
42 mV42\text{ mV}42 mV
140 mV140\text{ mV}140 mV
66 exam-style questions on AQA A Level Physics Magnetic fields (A-level only), covering Magnetic flux density (A-level only), Moving charges in a magnetic field (A-level only), Magnetic flux and flux linkage (A-level only), Electromagnetic induction (A-level only), Alternating currents (A-level only), and The operation of a transformer (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.