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Electromagnetism 2 a) i. State Lenz's law. (1 mark) ii. A coil is attached to an ammeter as shown in the figure below. A bar magnet is moved towards the coil and is then stops. State how the reading on the ammeter changes during this process. (1 mark) mmmmmmmm ← N iii. During the process an induced current is detected by the ammeter. The current is in the direction X to Y. Explain how this demonstrates Lenz's law. (2 marks) b) A vertical wire of length / is moved at constant velocity v through a uniform horizontal magnetic field of flux density B. What is the induced emf for the following cases (equation may be stated where relevant): i. Wire moves with velocity parallel to the magnetic field ii. Wire moves with velocity at right angles to the magnetic field (2 marks) c) A square coil is moved at constant velocity into a magnetic field of flux density 0.66 T shown in the figure below. An emf is induced in the coil, the voltage is 3.2 x 10-4 V. The length of a side of the square coil is 26 mm. Calculate the time taken to move the coil from position 1 to position 2. (2 marks) X X X X X Square coil X X X X X X X x 2 x X X X X X X X X X X X