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Chapter 30

Electromagnetic Induction

אינדוקציה
אינדוקציה
An emf is induced when the magnetic field in a coil is changed by pushing a bar magnet into or out of the coil. emfs of opposite signs are produced by ...
חוק פאראדיי
חוק פאראדיי
Faraday's law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in ...
חוק לנץ
חוק לנץ
The direction in which the induced emf drives the current around a wire loop can be found through the negative sign. However, it is usually easier to ...
Motional Emf
Motional Emf
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 ...
דינמו דיסק פאראדיי
דינמו דיסק פאראדיי
A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular ...
שדות חשמליים מושרים
שדות חשמליים מושרים
The fact that emfs are induced in circuits implies that work is being done on the conduction electrons in the wires. What can possibly be the source of ...
שדות חשמליים מושרים: יישומים
שדות חשמליים מושרים: יישומים
An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge ...
אדי זרמים
אדי זרמים
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in ...
זרם תזוזה
זרם תזוזה
Ampère's law, in its usual form, does not work in places where the current changes with time and is not steady. Thus, Maxwell suggested including ...
משמעות זרם העקירה
משמעות זרם העקירה
A displacement current is analogous to a real current in Ampère's law, participating in Ampère's law the same way as the usual ...
שדות אלקטרומגנטיים
שדות אלקטרומגנטיים
Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...
משוואת האלקטרומגנטיות של מקסוול
משוואת האלקטרומגנטיות של מקסוול
James Clerk Maxwell (1831–1879) was one of the major contributors to physics in the nineteenth century. Although he died young, he made major ...
סימטריה במשוואות מקסוול
סימטריה במשוואות מקסוול
Once the fields have been calculated using Maxwell's four equations, the Lorentz force equation gives the force that the fields exert on a charged ...
חוק אמפר-מקסוול: פתרון בעיות
חוק אמפר-מקסוול: פתרון בעיות
A parallel-plate capacitor with capacitance C, whose plates have area A and separation distance d, is connected to a resistor R and a battery of voltage ...
צורה דיפרנציאלית של משוואות מקסוול
צורה דיפרנציאלית של משוואות מקסוול
James Clerk Maxwell (1831–1879) was one of the significant contributors to physics in the nineteenth century. He is probably best known for having ...
גנרטור חשמלי: אלטרנטור
גנרטור חשמלי: אלטרנטור
Electric generators induce an emf by rotating a coil in a magnetic field. A simple alternator is an AC generator that creates electrical energy that ...
גנרטור DC
גנרטור DC
An alternator converts mechanical energy into electrical energy that varies sinusoidally, resulting in AC current. Meanwhile, a DC generator converts ...
EMF אחורי
EMF אחורי
Generators convert mechanical energy into electrical energy, whereas motors convert electrical energy into mechanical energy. A motor works by sending a ...
דמפינג מגנטי
דמפינג מגנטי
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a ...
מוליך-על
מוליך-על
A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a ...
סוגי מוליכי-על
סוגי מוליכי-על
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the ...
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