In an electric circuit the direction of electric current is in the

https://phys.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fphys.libretexts.org%2FBookshelves%2FUniversity_Physics%2FBook%253A_University_Physics_(OpenStax)%2FBook%253A_University_Physics_II_-_Thermodynamics_Electricity_and_Magnetism_(OpenStax)%2F09%253A_Current_and_Resistance%2F9.02%253A_Electrical_Current \( \newcommand\) • • • • • • • • LEARNING OBJECTIVES By the end of this section, you will be able to: • Describe an electrical current • Define the unit of electrical current • Explain the direction of current flow Up to now, we have considered primarily static charges. When charges did move, they were accelerated in response to an electrical field created by a voltage difference. The charges lost potential energy and gained kinetic energy as they traveled through a potential difference where the electrical field did work on the charge. Although charges do not require a material to flow through, the majority of this chapter deals with understanding the movement of charges through a material. The rate at which the charges flow past a location—that is, the amount of charge per unit time—is known as the electrical current. When charges flow through a medium, the current depends on the voltage applied, the material through which the charges flow, and the state of the material. Of particular interest is the motion of charges in a conducting wire. In previous chapters, charges were accelerated due to the force provided by an electrical field, losing potential energy...

Electric current Electric Current Electric current is the rate of R Nave Electric Charge The unit of electric charge is the Coulomb (abbreviated C). Ordinary matter is made up of atoms which have positively charged nuclei and negatively charged electrons surrounding them. Charge is quantized as a multiple of the electron or proton charge: The influence of charges is characterized in terms of the forces between them ( The rate of flow of electric charge is called In introducing one of the fundamental properties of matter, it is perhaps appropriate to point out that we use simplified sketches and constructs to introduceconcepts, and there is inevitably much more to the story. No significanceshould be attached to the circles representing the proton and electron, inthe senseof implying a relative size, or even that they are hard sphereobjects,although that's a useful first construct. The most importantopening idea,electrically, is that they have a property called "charge" which isthe samesize, but opposite in polarity for the proton and electron. Theproton has1836 times the mass of the electron, but exactly the same sizecharge, onlypositive rather than negative. Even the terms "positive" and"negative" arearbitrary, but well-entrenched historical labels. The essentialimplicationof that is that the proton and electron will strongly attract eachother, the historical archtype of the cliche "opposites attract".Twoprotons or two electrons would strongly repel each other. Once youhav...

The concept of electricity arises from an observation of nature. We observe a force between objects, that, like gravity, acts at a distance. The source of this force has been given the name charge. A very noticeable thing about electric force is that it is large, far greater than the force of gravity. Unlike gravity, however, there are two types of electric charge. Opposite types of charge attract, and like types of charge repel. Gravity has only one type: it only attracts, never repels. Conductors are made of atoms whose outer, or valence, electrons have relatively weak bonds to their nuclei, as shown in this fanciful image of a copper atom. When a bunch of metal atoms are together, they gladly share their outer electrons with each other, creating a "swarm" of electrons not associated with a particular nucleus. A very small electric force can make the electron swarm move. Copper, gold, silver, and aluminum are good conductors. So is saltwater. Insulators are materials whose outer electrons are tightly bound to their nuclei. Modest electric forces are not able to pull these electrons free. When an electric force is applied, the electron clouds around the atom stretch and deform in response to the force, but the electrons do not depart. Glass, plastic, stone, and air are insulators. Even for insulators, though, electric force can always be turned up high enough to rip electrons away—this is called breakdown. That's what is happening to air molecules when you see a spark. Se...

Q. Read carefully the statements given below and choose the correct option accordingly. Statement 1: Paper is a poor conductor of electricity Statement 2: Filament of a bulb is a thick wire Statement 3: Electric circuit can work without electric cell Statement 4: The direction of electric current is from positive terminal to negative terminal

\( \newcommand\) • Before we dive into series circuits we need to consider an interesting question involving the direction of current flow. Does it flow from positive to negative or from negative to positive? For that matter, does it even make a difference as far as our analyses will be concerned? Benjamin Franklin (pictured in Figure 3.2.1 ) began experimenting with the phenomenon of electricity in 1746. In 1752 he performed his famous kite experiment proving that lightning is a form of electricity by capturing charge from storm clouds in a leyden jar (an early form of an electrical charge storage device) 1. At this time the modern concept of an atomic model with electrons and protons did not exist and electricity was conceived of as a sort of fluid. Franklin surmised that the “electrical flow” moved from positive to negative. This idea was accepted and became the conventional view. Today we call this idea conventional current flow. In this model, current flows from a more positive voltage to a less positive voltage. We know now that the electron is the charge carrier in metals and the electrons travel in the reverse direction. Essentially, Franklin guessed wrong. Electrons move from a lower potential to a higher potential. We call this model electron flow. For most work, engineers and technicians use conventional flow, although in some cases, such as the explanation of semiconductors, electron flow is easier to visualize for some people. In short, conventional flow exist...

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reference directions" of the current i ( t ) With these definitions, passive components (loads) will have p> 0 and r> 0, and active components (power sources) will have p< 0 and r< 0. Explanation [ ] The arrows E represent the direction of the Active and passive components [ ] In electrical engineering, • In a source or on the moving charges by some source of energy in the component, to make them move in this direction against the opposing force of the E. • In a load or E in the direction of lower by the charges on the component; potential energy flows out of the charges; and electric power flows from the circuit into the component, where it is converted to some other form of energy such as heat or mechanical work. Some components can be either a source or a load, depending on the voltage or current through them. For example, a Since it can flow in either direction, there are two possible ways to define electric power; two possible reference directions: either power flowing into an electrical component or power flowing out of the component, which can be defined as positive. into the component ( out of the circuit) as positive, In an AC ( Reference directions [ ] The power flow p and r of an electrical component are related to the voltage v and current i variables by the defining equation for power and p = v i ( 1 ) Like power, voltage and current are signed quantities. The current flow in a wire has two possible directions, so when defining a current variable i the direc...