Question

A magneto is a device that creates a spark across a gap by creating a large voltage across the gap. To do this, the device spins a magnet very quickly in front of a wire coil, with the ends of the wires forming the gap. Explain how this creates a sufficiently large voltage to produce a spark.

a) The spinning magnet induces a current in the coil through electromagnetic induction.

b) The spinning magnet generates a high-frequency electromagnetic wave.

c) The gap acts as a capacitor, storing a charge that discharges as a spark.

d) The coil acts as a resistor, generating heat that produces a spark.

Answer 1

A magneto generates a large voltage to produce a spark by spinning a magnet in front of a wire coil, which induces a current and creates an emf due to the changing magnetic field. This voltage is large enough to create a spark across a gap.

Step-by-step explanation:

A magneto creates a sufficiently large voltage to produce a spark across a gap through the principles of electromagnetic induction. When the magnet inside the magneto spins quickly in front of the wire coil, the changing magnetic field around the coil induces a current, as per Faraday's law of electromagnetic induction. This induced current generates an electromotive force (emf) that is proportional to the rate of change of the magnetic flux through the coil. This process generates a large voltage that can overcome the electrical resistance of the air in the gap, resulting in a spark.

Devices such as electric generators operate on the same principle: they rotate a coil within a magnetic field to produce an alternating current emf. The rotational speed of the coil and other factors contribute to the voltage produced. Transformers, on the other hand, use magnetic induction to transform voltages from one value to another, and utilize coils to achieve this.