Faraday’s law of induction revolves around the law of electromagnetism, it adumbrates how magnetic fields interact with an electric circuit to produce an electromotive force (EMF), an anomaly known as electromagnetic induction. In this report, light will be shined on how this law is the foundation of the operation of electric guitars, apnea monitors, induction stoves and electromagnetic guns.
In 1831, Michael Faraday formulated two laws on the bases of experiments. These laws are called Faraday’s Laws of electromagnetic induction. The experiments shown that a current can be produced by a changing magnetic field, an example of the experiment is shown in figure 2.1.
Figure 2.1: Electromagnetic induction: inner coil(2) connected to liquid battery(3), outer coil(1) to galvanometer(4).
In figure 2.2, we can see a primary coil is connected to a battery, and a secondary coil is connected to an ammeter. There’s no battery in the secondary circuit, therefore when the switch is closed, the ammeter reads a current and then returns to zero, when the switch is opened, the ammeter reads a current in the opposite direction and then returns to zero and when there is a steady flow of current the primary circuit, the ammeter reads zero. His conclusions were that an electrical current is produced by a changing magnetic field and that the secondary circuit acts as if a source of emf were connected to it for a short time and therefore was founded that an induced emf is produced in the secondary circuit by the changing magnetic field.
Figure 2.2: Faraday’s Experiment
The emf is actually induced by a change in the quantity called the magnetic flux rather than simply by change in the magnetic field. The magnetic flux is defined in a manner similar to that of electrical flux where it is proportional to both the strength of the magnetic field passing through the plane of a loop of wire and the area of the loop.
In figure 2.3, there is a loop of wire in a uniformed magnetic field, the loop has an area “A”, and the flux is defined as:
?b = B • A • cos ?
Where “?” is the angle between B and the normal to the plan.
Figure 2.3: Loop of wire in a uniform magnetic field
When the field is perpendicular to the plane of the loop, ? = 0, and ?b = ?b max = B • A
When the field is parallel to the plane of the loop, ? = 90°, and ?b = 0
3.0 APPLICATIONS OF FARADAY’S LAW OF ELECTROMAGNETIC INDUCTION
Application of the Faraday’s law can be found in many devices, for this report we would look at the electric guitar, the apnea monitor, the induction stove and the electromagnetic gun, delving into how this law functions in each device.
3.1 The electric guitar
The electric guitar utilizes the idea of Faraday’s Law, additionally as different ideas associated with magnetism. All electrical guitars have a device referred to as a pickup that is placed beneath the magnetic guitar strings, these pickups are wire coils with a median of 4,000 to 7,000 turns. Once the magnetic string is plucked, it vibrates and changes the magnetic flux going through the coil, producing an emf through it, the emf is then sent to an amplifier, illustration is shown in figure 3.1.1.
Figure 3.1.1: Schematics of the electric guitar with magnetic dipole and pick-up coil.
In the Fender-style single-coil pickup there are six individual magnets, one for every string. The magnets are slim cylinders with either end being north and south pole. The magnets are held in place by a fibre or plastic plate as shown in figure 3.1.2. A thin wire is wounded directly around the chain of magnets, wounding could vary up to 8000.
Figure 3.1.2: Fender-style single-coil pickup assembly