Understanding Electromagnetic Induction: Faraday’s Law and Applications
Electromagnetic Induction: An Explanation
Electromagnetic induction: electric currents produce magnetic fields for action. The inductor coil loaded (or magnet) causes the onset of the current, inducing the coil (circuit) which generates the induced current.
Faraday’s Law Explained
Faraday’s conclusion: It generates an induced current when the inductor, the source magnetic field, and the induced coil move relative to each other. When the movement is in one direction, the galvanometer needle moves in one direction, and when the sense of movement changes, the galvanometer needle moves in the opposite direction. The intensity of the induced current is larger and faster when the relative movement of the inductor and induced coil is faster. This occurs because there is a variation in the lines of magnetic induction that cross the induced coil.
Electromotive Force (EMF)
Electromotive force: energy that a generator connects to a unit load. Faraday’s law states that when a conductor is introduced in a closed area where there is a magnetic field, the EMF induced is equal and opposite in sign to the rate at which the magnetic flux changes in the circuit.
Autoinduction and Mutual Induction
- Autoinduction: is the induction of a current by itself. Because it occurs, the intensity of current along the circuit must vary with time.
- Mutual induction: occurs when two circuits at a distance are able to induce current in one another.
Transformers: Modifying Voltage and Intensity
Transformers: are devices used to modify the voltage and intensity of an alternating current without significant energy losses. When no losses occur in the process, transformers are useful for energy transport, which allows the voltage to change at some point in the journey while maintaining constant power.
Electric Generators: Transforming Energy
Electric generators: are devices able to transform other types of energy into electricity.
Alternators and Dynamos
- Alternator: a generator of alternating current that periodically changes the direction of circulating electric charges.
- Dynamo: a generator of continuous current. It is called this because it changes the direction in which electric charges flow.
Power Plants: Generating Electricity
Power plants: In all power plants, the rotational movement of a turbine rotor is used to power an alternator. They differentiate by the energy source used:
Types of Power Plants
- Steam Power Plants: use a source of energy to convert water into steam that moves a turbine. Some power plants take advantage of the sun’s heat, concentrated by mirrors.
- Hydroelectric Power Plants: Use the potential energy of dammed water to move the blades of a turbine.
- Wind Turbines: Use the kinetic energy of wind to move a blade rotor.
- Solar Panel Power Plants: Exploit the photoelectric effect to produce electricity.
Variations in Circuits with Coils
If there is a coil in the circuit, it induces currents that oppose the appearance or disappearance of the current in the circuit. This also provokes a change in the magnetic flux through the turns of the coil. The induced current causes the bulb to reach its maximum brightness later, opposing the movement. When opening the circuit, the bulb turns off before the coil stops changing the magnetic flux.
Generating Electricity from Movement within a Magnetic Field
To generate electricity, there must be a variation of the magnetic flux, which remains the same and opposite in sign to the speed. (Formulas for the rest, and flow with the Angle)
The Induced Electric Current Loop
The induced electric current loop will only occur in the case where the flow of A, B, and C do not vary. In D, the magnetic flux through the loop varies over time, and therefore an induced electric current is generated.
Analyzing Graphs of Constant Flow
To maintain a constant flow, the flow must have a linear variation with respect to time. The only variable parameter is the third graphic.
Direction of Induced Current
The induced current will grow towards positive Z values. For the induced current, the magnetic field should cause a decrease in the opposite direction. On the upper side, it should be clockwise (southern) and lower (North).
Solenoid Behavior
In the solenoid, the induced current opposes the change of flow that occurs through it. As the vector magnetic field and the vector surface cross-section of the coil are parallel, the flow can be obtained through the coil.
Determining the Direction of Induced Current
If we know the magnetic field caused by the flow direction and orientation of the Z axis, we can indicate the direction of the induced current. The current will object to the change that produces a variation in the flow. As the flow is increased, the current opposes the flow field created by the magnet (opposite).