Back Emf
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01:24
Back EMF
0 Views •
2026
Generators convert mechanical energy into electrical energy, whereas motors convert electrical energy into mechanical energy. A motor works by sending a current through a loop of wire located in a magnetic field. As a result, the magnetic field exerts a torque on the loop. This rotates a shaft, extracting mechanical work from the electrical current sent in initially. When the coil of a motor is turned, magnetic flux changes through the coil, and an emf (consistent with Faraday's law) is induced.
01:22
Motional Emf
0 Views •
2023
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation with respect to the surface area. If any of these quantities vary, a corresponding variation in magnetic flux occurs. If the area through which the magnetic field lines are passing changes, then the magnetic flux also changes. This change in the area can be of two types: the flux through the rectangular loop increases as it moves into the magnetic...
01:26
Applications of EMF Measurements
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2026
Electromotive force (EMF) measurements have a broad range of applications in various fields, including chemistry and physics. The electrochemical series, an arrangement of elements in order of their standard electrode potentials, can be determined through EMF measurements. Elements with lower standard potentials can reduce ions of elements with higher standard potentials.The standard cell potential, E°, allows for the calculation of the standard reaction Gibbs energy, ΔG°, and the equilibrium...
11:33
Inductance
0 Views •
2023
Source: Yong P. Chen, PhD, Department of Physics & Astronomy, College of Science, Purdue University, West Lafayette, IN This experiment will use inductive coils to demonstrate the concept of inductor and inductance. Magnetic induction will be demonstrated using a rod magnet inserted into or extracted away from the core of a coil to induce a transient electromotive force (emf) voltage in the coil, measured by a voltmeter. This experiment will also demonstrate the mutual inductance between...
10:04
Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging
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Cited by 27 •
2017
Amyloid deposition is a hallmark of different diseases and afflicts many different organs. This paper describes the application of luminescent conjugated oligothiophene fluorescence staining in combination with fluorescence microscopy techniques. This staining method represents a powerful tool for detection and exploration of protein aggregates in both clinical and scientific setups.
FAQs
At startup, the rotor is not yet moving fast enough to produce a substantial opposing voltage in the windings. Consequently, little of the applied voltage is offset, so more remains available to drive winding current. As rotation develops, the induced opposition grows and limits the current, producing the characteristic reduction from starting current to operating current.
Rotor motion changes the magnetic flux linked with the motor windings, and faster rotation generally produces a larger induced voltage. This speed dependence makes the opposing voltage a direct electrical indication of the motor’s rotational state. A stationary or slowly moving rotor therefore produces less opposition than one turning at its normal operating speed.
A heavier load can reduce rotational speed, which lowers the opposing voltage generated in the windings. With less opposition to the supply, the winding current increases. This interaction links mechanical loading and electrical behavior: changes in rotation alter current, while the resulting electrical conditions help explain how the motor responds to its load.
A motor model accounts for the applied supply voltage, the opposing induced voltage, winding current, and rotational speed as related quantities. The speed-dependent voltage explains why current is high during starting but lower during normal operation. Such modeling helps researchers analyze motor behavior without treating electrical and mechanical operation as separate systems.
Because its magnitude generally increases with rotational speed, the induced voltage provides information about the motor’s operating state. Speed-regulation analysis can use this relationship to connect measured electrical behavior with rotation and assess whether the motor is approaching or departing from its intended operating condition. This makes the effect useful in controlling motor performance.
Fault-diagnosis work can compare the motor’s expected relationship among supply voltage, induced opposition, current, and rotational speed with its observed behavior. Deviations from the modeled relationship may indicate that the motor is not operating as expected. The value of this approach is that it uses coupled electrical and mechanical behavior rather than examining current or speed in isolation.