4 13142.03 Question 1 Requirements • 2 × 1 ‘magnadur’ or ‘alnico’ magnets (e.g. Timstar MA10130) • retort stand, boss and clamp • string • stop-clock • half metre rule • 30 cm ruler • 2 cm cube block of non-magnetic material • blu-tac • tape Preparation Clamp the half metre rule horizontally from the retort stand. Suspend one of the magnets from the half metre rule using the string as shown in Fig 1.1. The magnet can be taped to the string. The magnet should be between 40–42 cm below the half metre rule. Ensure that the magnet is horizontal. Front view Side view half metre rule string magnets magnets y y A B Fig 1.1 Use blu-tac to stick the other magnet onto the desk directly below the suspended magnet so that the two magnets attract. Adjust the clamp in the retort stand until the distance between the magnets is approx. 5.5 cm. Place a small piece of blu-tac on the cube. Set the cube and stop- clock close to the apparatus Action at Changeover Remove the magnet from the cube and stick the magnet to the desk in its original position. Set the cube close to the apparatus. Check that the height of the suspended magnet has not been adjusted. Reset the stop-clock.