Hard to explain and fully grasp as it's can be a very confusing concept, but I'll try.
In the first case, the magnet has a field around it like this
http://www.electronics-tutorials.ws/electromagnetism/mag2.gifAs the magnet approaches the coil in your first case due to a force on it towards the
right, the magnet and coil get closer, so there's an
increase in flux linkage through the coil, see
In your case it's a bit like initially 0 field lines through coil and then, say, 5 field lines through coil, so an increasein flux linkage through the coil
By Faraday's law there's an induced emf in the coil which has a magnitude directly proportional to the rate of change of flux linkage through the coil. The induced emf causes a current to flow in the coil and this current in the coil sets up a magnetic field around the coil, see
http://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Electromagnetism.svg/220px-Electromagnetism.svg.pngAlso using Fleming's right hand grip rule you can determine the
conventional current direction if you know the field direction or you can determine the field direction if you know the conventional current direction. This explains how you use the rule
http://www.electricyouniverse.com/eye/thumbs/lrg-69-fleming-hand-rules3.jpghttp://4.bp.blogspot.com/-8e_cyTZXHwk/TaHOHZ7nzzI/AAAAAAAAAbY/WQDcj4Ynna8/s400/Right-Hand-Grip-Rules2.pngBy Lenz's law the induced emf acts in a direction in the coil such that it opposes the flux change that caused it. We know that originally the flux change was caused by the magnet moving to the
right due to a force on it to the right, so the current in the coil causes a field around the coil which points to the
left, in the
opposite direction to the field from the magnet, after all field lines are like force lines, so the magnet experiences a force to the
left and is pushed back to the left. Now, we know that the current in the coil forms a field pointing to the left, allowing us to use Fleming's right hand grip rule to work out the current direction in the coil.
You try the second case.
http://www.thestudentroom.co.uk/showthread.php?t=2552892Try doing the question there, it can really help you grasp the concept. Then see my long post below on the thread for my explanation oaf the solution.