Electric Current Magnetism
Electric Current Magnetism - Related Videos
09:12
Electric Charge in a Magnetic Field
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2023
Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA This experiment duplicates J.J. Thomson's famous experiment at the end of the 19th century, in which he measured the charge-to-mass ratio of the electron. In combination with Robert A. Millikan's oil-drop experiment a few years later that produced a value for the charge of the electron, the experiments enabled scientists to find, for the first time, both the mass and the charge of the electron, which are key...
01:10
Electrical Current
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2023
Electrical current is defined as the rate at which charge flows. When there is a large current present, such as that used to run a refrigerator, a large amount of charge moves through the wire in a small amount of time. If the current is small, such as that used to operate a handheld calculator, a small amount of charge moves through the circuit over a long period of time. The SI unit for current is the ampere (A), named for the French physicist André-Marie Ampère (1775–1836). An ampere is the...
10:25
Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging
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Cited by 18 •
2017
Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations, though its effects are not completely understood. This article describes a safe and reliable setup for applying tACS simultaneously with functional magnetic resonance imaging, which can increase understanding oscillatory brain function and effects of tACS.
01:16
Magnetic Field Of A Current Loop
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2025
Consider a circular loop with a radius a, that carries a current I. The magnetic field due to the current at an arbitrary point P along the axis of the loop can be calculated using the Biot-Savart law. Let axial point P be a distance x from the center of the loop. The magnetic field at P, produced by an infinitesimal current element dl, is directed at an angle θ. The current element and the unit vector along the line joining P are perpendicular at all points on the loop. Substituting this and...
01:13
Magnetic Force Between Two Parallel Currents
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2026
Two long, straight, and parallel current-carrying conductors exert a force of equal magnitude on one another. The direction of the force depends on the current direction in the conductors. The force exerted by the magnetic field due to the first conductor over a finite length of the second conductor is given as the product of the current in the second conductor and the vector product of the length vector along the current element and the field due to the first conductor. According to the...
FAQs
The right-hand rule links the direction of charge flow to the orientation of the surrounding magnetic field. Point the thumb in the direction of conventional current, and the curled fingers indicate the field’s direction around the conductor. This relationship helps physicists analyze individual wires, compare field orientations, and predict how conductors interact within electromagnetic devices.
Coiling the wire concentrates the magnetic field produced by current into a more organized arrangement. Rather than spreading the field around a single straight conductor, the turns work together to create an electromagnet. This configuration makes current-produced magnetism useful for devices that require a controllable magnetic effect, including motors and scientific instrumentation.
Electric motors and generators use the same connection between current, motion, and magnetic fields but operate in opposite directions. A motor uses electrical energy to produce motion, whereas a generator uses motion to induce electric current. Comparing them clarifies how electromagnetic systems can either deliver mechanical motion from a circuit or produce electricity from mechanical motion.
A transformer transfers electrical energy between circuits through a changing magnetic field. The field provides the connection between the circuits without treating them as one continuous circuit in the explanation provided. This principle is important in power systems because it allows electrical energy to be transferred between separate circuit arrangements while relying on electromagnetic coupling.
Begin by identifying the conductor through which electric charge flows and establishing the current direction. Apply the right-hand rule to determine the surrounding magnetic-field direction, then check whether the conductor is coiled. If it is, interpret the concentrated field as an electromagnet. This sequence connects circuit behavior with the magnetic pattern and likely device function.
A coiled conductor is useful when an application requires the magnetic effect of current to be concentrated rather than distributed around a single straight wire. The resulting electromagnet supports analysis and design of electromagnetic devices, including electric motors and scientific instrumentation. Researchers can therefore relate the coil’s arrangement to the intended magnetic function of the system.
The interaction between current and magnetic fields provides the operating basis for several power technologies. Motors convert electrical energy into motion, generators convert motion into induced current, and transformers transfer energy between circuits through changing fields. Together, these applications show why electromagnetic principles are essential for analyzing power systems and the devices that connect electrical and mechanical energy.