The charged pith ball is put at the center of a gold spherical shell of inner radius 2. Two parallel conducting plates, each of cross-sectional area , are 2. If electrons are transferred from one plate to the other, a what is the potential difference between the plates? A point charge of is placed at the center of an uncharged spherical conducting shell of inner radius 6.
Find the electric potential at a b c. Point charges of are placed 0. What can you say about two charges , if the electric field one-fourth of the way from is zero? Calculate the angular velocity of an electron orbiting a proton in the hydrogen atom, given the radius of the orbit is. You may assume that the proton is stationary and the centripetal force is supplied by Coulomb attraction. An electron has an initial velocity of in a uniform electric field. The field accelerates the electron in the direction opposite to its initial velocity.
Three and three ions are placed alternately and equally spaced around a circle of radius 50 nm. Find the electrostatic energy stored. Look up presumably online, or by dismantling an old device and making measurements the magnitude of the potential deflection plates and the space between them in an ink jet printer.
Then look up the speed with which the ink comes out the nozzle. Can you calculate the typical mass of an ink drop? Answers will vary. This appears to be proprietary information, and ridiculously difficult to find. Use the electric field of a finite sphere with constant volume charge density to calculate the electric potential, throughout space. Then check your results by calculating the electric field from the potential. Calculate the electric field of a dipole throughout space from the potential.
Apply with to the potential calculated earlier, with and assume that the axis of the dipole is aligned with the z -axis of the coordinate system. Thus, the potential is. Skip to content Electric Potential. The Van de Graaff Generator Van de Graaff generator s or Van de Graaffs are not only spectacular devices used to demonstrate high voltage due to static electricity—they are also used for serious research.
Schematic of Van de Graaff generator. A battery A supplies excess positive charge to a pointed conductor, the points of which spray the charge onto a moving insulating belt near the bottom.
The pointed conductor B on top in the large sphere picks up the charge. The induced electric field at the points is so large that it removes the charge from the belt.
This can be done because the charge does not remain inside the conducting sphere but moves to its outside surface. An ion source inside the sphere produces positive ions, which are accelerated away from the positive sphere to high velocities.
Xerography is a dry copying process based on electrostatics. The major steps in the process are the charging of the photoconducting drum, transfer of an image, creating a positive charge duplicate, attraction of toner to the charged parts of the drum, and transfer of toner to the paper. Not shown are heat treatment of the paper and cleansing of the drum for the next copy.
Laser Printers Laser printers use the xerographic process to make high-quality images on paper, employing a laser to produce an image on the photoconducting drum as shown in Figure. In a laser printer, a laser beam is scanned across a photoconducting drum, leaving a positively charged image.
The other steps for charging the drum and transferring the image to paper are the same as in xerography. Laser light can be very precisely controlled, enabling laser printers to produce high-quality images. The nozzle of an ink-jet printer produces small ink droplets, which are sprayed with electrostatic charge. Your photocopier or Xerox machine uses static electricity to copy print to a page. This is done through the science of xerography. One version of this device electrically charges ink so that it will stick to the paper in the designated areas.
Another version of a photocopier uses charges to stick the ink to a drum, which then transfers it to the paper. Some automobile manufacturers use static electricity to help them paint the cars they make.
The way this works is that they first prepare the car's surface and then put it in a paint booth. Next, they give the paint an electrical charge and then spray a fine mist of paint into the booth. The charged paint particles are attracted to the car and stick to the body, just like a charged balloon sticks to a wall. Once the paint dries, it sticks much better to the car and is smoother because it is evenly distributed. Uses of static electricity include pollution control, Xerox machines, and painting.
The Integrated Concepts exercises for this module involve concepts such as electric charges, electric fields, and several other topics.
Physics is most interesting when applied to general situations involving more than a narrow set of physical principles. The following worked example illustrates how this strategy is applied to an Integrated Concept problem:. Suppose a tiny drop of gasoline has a mass of 4. To solve an integrated concept problem, we must first identify the physical principles involved and identify the chapters in which they are found.
Part a of this example asks for weight. Part b deals with electric force on a charge, a topic of Electric Charge and Electric Field. Part c asks for acceleration, knowing forces and mass. The following solutions to each part of the example illustrate how the specific problem-solving strategies are applied.
These involve identifying knowns and unknowns, checking to see if the answer is reasonable, and so on. Weight is mass times the acceleration due to gravity, as first expressed in. Entering the given mass and the average acceleration due to gravity yields.
The force an electric field exerts on a charge is given by rearranging the following equation:. Here we are given the charge 3. Since the drop has a positive charge and the electric field is given to be upward, the electric force is upward. This is an upward acceleration great enough to carry the drop to places where you might not wish to have gasoline. This worked example illustrates how to apply problem-solving strategies to situations that include topics in different chapters.
The first step is to identify the physical principles involved in the problem. The second step is to solve for the unknown using familiar problem-solving strategies.
These are found throughout the text, and many worked examples show how to use them for single topics. In this integrated concepts example, you can see how to apply them across several topics. You will find these techniques useful in applications of physics outside a physics course, such as in your profession, in other science disciplines, and in everyday life.
The following problems will build your skills in the broad application of physical principles. The Unreasonable Results exercises for this module have results that are unreasonable because some premise is unreasonable or because certain of the premises are inconsistent with one another. Physical principles applied correctly then produce unreasonable results. The purpose of these problems is to give practice in assessing whether nature is being accurately described, and if it is not to trace the source of difficulty.
To determine if an answer is reasonable, and to determine the cause if it is not, do the following. As an Amazon Associate we earn from qualifying purchases. The electrostatic force is a force exerted by the particles of a charged body on the particles of a charged or uncharged body. It is one of the four fundamental forces of nature. The electrostatic force is a non-contact force. It deals with the stationary electric charges.
In short, a force of attraction or repulsion that exists between the charged particles of two objects is known as electrostatic force. The electrostatic force is often simply known as an electric force. This electrostatic force developed between the skin and the clothing particles is accountable for the chattering sound caused while removing such clothes.
To avoid static getting developed on a nylon cloth, a fabric softener must be added while washing it. When a rod is rubbed with a cloth, it tends to develop a certain charge on it.
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