Electromagnetic induction

As the wire moves through the magnetic field, it cuts through the magnetic field lines. This causes free electrons within the wire to experience a force due to the magnetic field. This force causes the electrons to move along the wire, creating a potential difference (e.m.f.) between the ends of the wire. This effect is known as electromagnetic induction.

1. Increase the speed at which the magnet is moved towards the coil.
2. Increase the number of turns on the coil.

Diagram:
* A coil of wire connected to a galvanometer.
* A bar magnet.

Procedure:
1. Hold the bar magnet stationary near the coil. Note the galvanometer reading. (Reading should be zero)
2. Move the bar magnet into the coil. Note the galvanometer reading. (Reading should deflect)
3. Hold the bar magnet stationary inside the coil. Note the galvanometer reading. (Reading should be zero)
4. Move the bar magnet out of the coil. Note the galvanometer reading. (Reading should deflect in opposite direction to step 2)

Observation: A deflection on the galvanometer indicates an induced current. The current only flows when the magnetic field experienced by the coil is changing.

1. Increase the speed at which the magnet is moved relative to the coil.
2. Use a stronger magnet.

1. The speed of the movement of the coil relative to the magnetic field. A faster movement produces a larger induced e.m.f.
2. The strength of the magnetic field. A stronger magnetic field produces a larger induced e.m.f.
3. The number of turns in the coil. More turns produce a larger induced e.m.f. Each turn experiences the change in magnetic flux, so more turns give a larger overall effect.

Increasing the number of turns in the coil increases the induced e.m.f. Each turn of the coil experiences a small e.m.f. due to electromagnetic induction. By adding more turns, these small e.m.f. values add up in series, resulting in a larger overall induced e.m.f. Therefore, the induced e.m.f. is directly proportional to the number of turns.

The direction of the induced e.m.f. opposes the change in magnetic flux to conserve energy. If the induced e.m.f. aided the change, the change would increase, inducing an even larger e.m.f., leading to a perpetual motion scenario and violation of the law of conservation of energy. This opposition is described by Lenz's Law.

The galvanometer needle will deflect. As the magnet approaches the coil, the magnetic flux through the coil changes. This induces an e.m.f. in the coil, causing a current to flow. The direction of the induced current creates a magnetic field that opposes the motion of the magnet (Lenz's Law).

The induced current is to the left. This is determined by Fleming's Right-Hand Rule: First finger points in the direction of the magnetic field (into the page), the thumb points in the direction of the motion (downwards). The second finger then indicates the direction of the induced current (to the left).

The force on the wire is upwards. According to Lenz's Law, the induced current will create a magnetic field that opposes the change causing it. Since the wire is moving to the right (creating a current), the magnetic force will act against the motion to the right. Using Fleming's Left-Hand Rule (current to the right, magnetic field into the page), the force opposes the motion and is upwards.