Final answer:
When a magnet is thrust into a coil, the force exerted by the coil depends on the direction of the magnetic field and the current induced in the coil. The direction of the current and force can be determined using the right-hand rule. The magnitude of the force depends on the resistance of the galvanometer.
Step-by-step explanation:
When a magnet is thrust into a coil, the force exerted by the coil on the magnet depends on the direction of the magnetic field and the current induced in the coil. Let's consider a specific scenario where the north end of the magnet is moving towards the left-hand side of the coil. In this case, a positive voltage is produced as the magnet enters the coil. The current flows in a direction so that the face of the coil nearer the magnet becomes a north pole, which then attracts the approaching north pole of the magnet. This is determined by using the right-hand rule, where your thumb points away from the magnet and your fingers wrap around in a clockwise direction.
The magnitude of the force exerted by the coil on the magnet is dependent on the resistance of the galvanometer. The force is directly proportional to the current induced in the coil, which is inversely proportional to the resistance of the galvanometer according to Ohm's law (V = IR). Therefore, as the resistance of the galvanometer increases, the magnitude of the force exerted by the coil on the magnet decreases.