The study of electrostatics has proven useful in many areas. This module covers just a few of the many applications of electrostatics. Van de Graaff generators 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.
The first was built by Robert Van de Graaff in based on original suggestions by Lord Kelvin for use in nuclear physics research. Van de Graaffs utilize both smooth and pointed surfaces, and conductors and insulators to generate large static charges and, hence, large voltages. A battery part A in Figure 1 supplies excess positive charge to a pointed conductor, the points of which spray the charge onto a moving insulating belt near the bottom.
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.
A very large excess charge can be deposited on the sphere, because it moves quickly to the outer surface. Practical limits arise because the large electric fields polarize and eventually ionize surrounding materials, creating free charges that neutralize excess charge or allow it to escape.
Nevertheless, voltages of 15 million volts are well within practical limits. Rub a comb through your hair and use it to lift pieces of paper. It may help to tear the pieces of paper rather than cut them neatly.
Repeat the exercise in your bathroom after you have had a long shower and the air in the bathroom is moist.
Is it easier to get electrostatic effects in dry or moist air? Why would torn paper be more attractive to the comb than cut paper?
Explain your observations. Most copy machines use an electrostatic process called xerography —a word coined from the Greek words xeros for dry and graphos for writing. The heart of the process is shown in simplified form in Figure 2. A selenium-coated aluminum drum is sprayed with positive charge from points on a device called a corotron. Selenium is a substance with an interesting property—it is a photoconductor. That is, selenium is an insulator when in the dark and a conductor when exposed to light.
In the first stage of the xerography process, the conducting aluminum drum is grounded so that a negative charge is induced under the thin layer of uniformly positively charged selenium. In the second stage, the surface of the drum is exposed to the image of whatever is to be copied.
Examples of Potential Energy
Where the image is light, the selenium becomes conducting, and the positive charge is neutralized. In dark areas, the positive charge remains, and so the image has been transferred to the drum. The third stage takes a dry black powder, called toner, and sprays it with a negative charge so that it will be attracted to the positive regions of the drum. Next, a blank piece of paper is given a greater positive charge than on the drum so that it will pull the toner from the drum.
Electric potential energy and its applications. Thread starter Ahmad Syr Start date Aug 23, Ahmad Syr. Hi guys I just want to make sure that my understanding of potential difference is right or wrong I just want someone to tell me whether my understanding is right or wrong.
I know that when we move a charge if it's attracted to another charge it gain potential energy and when we leave it it lose energy as kinetic energy and in a battery the electrons have potential energy and they lose it as they travell from the negative terminal to the positive terminal as kinetic energy and also voltage drop affect their energy right????????
Related Electrical Engineering News on Phys. The KE gained per unit charge in the first case or the work done per unit charge as in the 2nd case in moving a charge from one potential to the other is defined as the Potential difference. And they may lose energy as heat as they travel through the resistors right?????
Yes, and that heat energy dissipated per unit charge across the resistor is also equivalent to the work done per unit charge. Why changing magnetic flux in a coil induce a current can you explain that electronically. NascentOxygen Staff Emeritus. Science Advisor. Ahmad Syr said:. You must log in or register to reply here. Related Threads on Electric potential energy and its applications Relay and its application.
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When a diver jumps off a high board into a swimming pool, he hits the water moving pretty fast, with a lot of kinetic energy. Where does that energy come from?
The use of electric fields in tissue engineering
The answer is that gravitational force his weight does work on the diver as he falls. However, there is a very useful alternative way to think about work and kinetic energy. This new approach is based on the concept of potential energy, which is the energy associated with the position of a system rather than its motion.
In this approach, there is gravitational potential energy even while the diver is standing on the high board. And also we will see how the work-energy theorem explains this transformation. If the diver bounces on the end of the board before he jumps, the bent board stores the second kind of potential energy called elastic potential energy. We will discuss the elastic potential energy of simple systems such as a stretched or compressed spring.Physics 12.4.1b - Electric Potential and Potential Difference, continued
An important third kind of potential energy is associated with the positions of electrically charged particles relative to each other.
This will lead us to the general statement of the law of conservation of energy, one of the most fundamental and far-reaching principles in all of science. When we stretch a rubber band or lift a stone to some height, energy is stored in these objects. This energy is called potential energy.
A brick on the ground cannot do any work. But when we raise the same brick, energy is stored in these objects. The energy in the wound-up spring of a toy car is potential energy. This energy can cause a toy car to move. When we put a stone in the sling of a catapult and stretch its rubber, potential energy stored in it.
This energy can throw away the stone. Similarly, the water stores in the dam have potential energy. When we fill a balloon, we are forcing a gas to remain in a delimited space.
The pressure exerted by this air stretches the walls of the balloon. When we finish filling the balloon, the system stands still.
However, the compressed air within the balloon has a large amount of potential energy. If a balloon explodes, this energy is converted into kinetic and sound energy. While suspended, it has potential gravitational energy, which will be available as soon as it is disconnected from the branch.Hot Threads.
Electric potential energy and its applications. Thread starter Ahmad Syr Start date Aug 23, Ahmad Syr. Hi guys I just want to make sure that my understanding of potential difference is right or wrong I just want someone to tell me whether my understanding is right or wrong. I know that when we move a charge if it's attracted to another charge it gain potential energy and when we leave it it lose energy as kinetic energy and in a battery the electrons have potential energy and they lose it as they travell from the negative terminal to the positive terminal as kinetic energy and also voltage drop affect their energy right????????
Related Electrical Engineering News on Phys. The KE gained per unit charge in the first case or the work done per unit charge as in the 2nd case in moving a charge from one potential to the other is defined as the Potential difference. And they may lose energy as heat as they travel through the resistors right????? Yes, and that heat energy dissipated per unit charge across the resistor is also equivalent to the work done per unit charge. Why changing magnetic flux in a coil induce a current can you explain that electronically.
NascentOxygen Staff Emeritus.
Science Advisor. Ahmad Syr said:.The use of electric fields for measuring cell and tissue properties has a long history. However, the exploration of the use of electric fields in tissue engineering is only very recent. A review is given of the various methods by which electric fields may be used in tissue engineering, concentrating on the assembly of artificial tissues from its component cells using electrokinetics.
A comparison is made of electrokinetic techniques with other physical cell manipulation techniques which can be used in the construction of artificial tissues. The investigation of the electrical properties of biological materials and their applications has a long history. Tissue engineering, in contrast, is a relatively more recent field of investigation, and the exploration of the use of electric fields for characterizing or actively making artificial tissues has only just begun.
However, as research in this highly competitive field is expanding rapidly, a review of the use of electric fields in tissue engineering appears very timely. The main applications of electric fields in tissue engineering are in the characterisation of artificial tissues and its component cells, and the formation of artificial tissue-like materials, either by assisting in the formation of the artificial extracellular matrix e.
Of further potential interest in tissue engineering are also the biological effects of the electric fields. In this review we will briefly discuss all these topics, concentrating on the manipulation of cells using electrokinetic techniques. The electrical properties of tissues are mainly determined by their capacitance and conductance.
Both are frequency-dependent, and the frequency range over which the electrical properties of tissues can be measured ranges from subHz to the microwave range Giga-TeraHz. A large variety of techniques have been developed for the measurement of the electrical properties of tissues, contact as well as non-contact methods.
Reviews of the electrical properties of natural tissues have been given by various authors. An important potential application of dielectric measurements on engineered tissues is the on-line and continuous measurement of the cell concentration and its distribution within a tissue construct.
Capacitance measurement of cell concentrations in tissue constructs. A Capacitance at 0. B Constantly monitoring the capacitance at 0. The gel was inoculated with Of interest in tissue engineering are also impedance measurements on adherent cells growing as confluent cell layers over an electrode surface.
Electrospinning typically involves the application of a high voltage usually several kV to a polymer solution or polymer melt between a conductive die usually a capillary and a counterelectrode.
The high electrical field generated between the capillary and the counterelectrode causes the formation of a fine fluid jet, from which nanofibers are formed which can be used as scaffolds. Under most circumstances cells have a net negative charge, and when a DC electric field is applied to a cell suspension the cells are readily moved by electrophoresis. By generating positive voltages at micropatterned electrodes electrophoresis can be used to attract and pattern cells.
This large external DC electric field elicits very high electric fields across the cell membrane, which can adversely affect cell viability. The other disadvantage of the use of DC electric fields for patterning cells is that other effects such as electro-osmotic flow of the medium and heating effects give rise to flows near the electrodes. This makes it difficult to control cell movement, whilst excessive heating can also affect cell viability.
Reducing the medium conductivity by replacing conductive salts by nonconductive sugars can alleviate these problems to some extent. Although electro-osmotic and heating effects also occur in AC electric fields, these effects significantly reduce with increasing frequency, and at frequencies over 1 MHz they can often be neglected.
AC electric fields across the membrane also decrease with increasing frequency, and thus AC electric fields are preferable for cell manipulation over DC fields.We can control the speed of the fans at our homes by moving the regulator to and fro.
Here the current flowing through the fan is controlled by regulating the resistance through the regulator. A circular knob on the component can be rotated to achieve a variable resistance on the output terminals. The electric heaters are the common appliances used in winters throughout the world. The heaters have a metal coil which has high resistance that permits a certain amount of current to flow through them to provide the required heat.
Also, the power to be supplied to the heaters is calculated using this law. The electric kettle and irons have a lot of resistors in them. The resistors limit the amount of current to flow through them to provide the required amount of heat.
The electronic devices such as laptop and mobile phones require a DC power supply with the specific current. Many devices need a certain amount of current and voltage to operate. Ohms law tells us the amount of resistance we need to establish a certain current with a certain amount of voltage. Fuses are the protection components that limit the amount of current flowing through the circuit and to establish a certain amount of voltage. They are connected in the series in the device.
Ohms law is used to figure out which resistors are needed. Mobile and Laptop chargers use DC power supply in the operation.The pitcher winds up, then pitches. He demonstrates both potential energy in the windup, and kinetic energy in the pitch. Potential energy is stored energy ready to release: a roller coaster at the top of its first peak, a car ready to descend a San Francisco street, an eager student ready to leave his desk.
The subsequent action is kinetic energy -- the energy of motion released. Both apply to numerous everyday situations. The electricity that fuels people's homes is supplied by potential energy turned kinetic, either in the form of an electric plant fueled by coal, a hydroelectric dam, or other source such as solar cells. The coal is stored potential energy at its most inert; it must be burned to translate itself into kinetic energy. The water behind the dam is, despite its eddies and currents, relatively inert as well, but it also supplies power when it is transformed by flowing through the dam and transferring it kinetic energy.
Switch on the light. The switch's movement releases potential energy, while the light is kinetic. Cars on the road offer another example of potential-to-kinetic energy, whether driving a gasoline-fueled automobile or an electrically powered model. The fuel stored in a gasoline-powered car's tank is potential energy, ready to be used for transportation; the ignition, spark and firing of the engine begin the potential-to-kinetic cycle, and the car's response as it leaves the driveway and heads onto the road is an extension of kinetic movement.
Electric cars store their potential energy in batteries, waiting for the switch-on that begins their driver's kinetically-powered trip.
Kinetic energy seldom ends with a single reaction. In sports, for example, the release of potential energy found in a tautly-strung tennis racket or a drawn bow -- called elastic potential energy -- often results in several kinetic reactions. When you hit a tennis ball, the kinetic energy is released in the ball's flight, but it redoubles in energy and speed if your opponent returns the ball to you.
The stored potential energy of the strung racket is transferred to the ball's kinetic explosion of flight. Rainwater becomes a dam's power resource. A moving car hits a stationary car, causing it to move as well. A football sails towards a quarterback, while a baseball crashes through a window. All these potential-to-kinetic actions and reactions are examples of the law of conservation of energy, which reminds us that energy is never destroyed, but only transferred, moving from the rainy sky to the rushing dam, or from the baseball player's hand to the shattered window.
He has taught English at the level for more than 20 years. He has written extensively in literary criticism, student writing syllabi and numerous classroom educational paradigms. About the Author. Copyright Leaf Group Ltd.