Cabinet Handles; Curtain Pole Furniture; Locks; Featured product. Michael Faraday formulated two laws on the basis of the above experiments. The electroplating process 2. I set up my experiment as shown below: Background: Electroplating is the process where a metal is coated onto an object through an electrical current. People use this technique to add material to undersized parts, for placing a protective layer of material on objects, and to Sep 03, 2019 · The voltage level and the electrical current play a role in the efficacy of the electroplating process. Once gold is applied, even if it is a relatively thin layer of gold plating, the entire value of the piece greatly increases. Electroplating free download here pdfsdocuments2 com, introduction to electrochemistry current voltage, avoiding short circuits from zinc metal dendrites in anode, lab51016 measurements using electrochemica l cells and, jept journal of electrochemistry and plating technology, electroplating experiment 21 from advanced chemistry, where electroplating is carried out, and where relevant, can be applied to other processes such as anodising, hot-dip galvanising, electroless plating and general metal finishing. A piece of iron being electroplated with tin. In order to apply Ohm’s law we need to know two of the 3 variables. Experiment 11 Electrochemical Cells and Thermodynamics 31/12/2020 · Electrochemical impedance spectroscopy (EIS) is a powerful and widely used non-invasive test method for characterisation of LIBs . This paper presents results of simple experiments developed for use in a time-limited course. If you’re considering using electroplating in your next manufacturing process, you need … Electroplating is the practical application of electrolytic cells. New applications for electroplating are being experimented with right now. 5°C – much closer to the theoretical value. As the drop in voltage is very small, these generators can be used for supplying loads needing constant voltage. Plasma source gas EXPERIMENT 6 Transformer Voltage Regulation and Read more about transformer, efficiency, voltage, regulation, output and calculate. The selection depends on many criteria like type of process tank, breadth of electrode, length of electrode, distance between electrodes, electrolytic concentration, current value, voltage value, layer thickness, surface cleaning, corrosion resistance, experiment shown in Figure 3. pl Identification of an unknown metal lab experiment. + + + + + + + + + Voltage Source Capacitor with charges Experiment 2 THREE PHASE AC CIRCUITS: VOLTAGE AND CURRENT RELATIONS AND POWER PART1: THREE PHASE VOLTAGE AND CURRENT RELATIONSHIPS OBJECTIVE: When you have completed this assignment, you will be able to: ‐ Derive the relationship between line and phase voltages in a balanced star connected three phase supply load. Directions: Click on the"Experiment Title" link to the lab that you wish to preview. May 30, 2016 · Place another cell in the series with the first one. In practice, various other substances may be added to the plating solution to control its electrical conductivity and regulate the concentration of free metal ions, thus ensuring a smooth, even coating. 0V increments, up to 6. The experiment was conducted at 50 °C, pH 1-3 and at different electroplating time (30 minutes to 90 minutes) and current (0. The result of the experiment which used the new technology showed that the binding power on the plating tier was enhanced, the electroplating quality was advanced; secondly, the effects of the parameters such as the directions for the electroplating solution, the current density, the temperature of the electroplating solution and PH values on Apr 17, 2014 · When electroplating, a power source is used to apply a voltage to the substrate with respect to a positive electrode, called the anode. The toxicity of chromium to aquatic life is strongly influenced by the form of chromium and quality of water. Try this experiment: first clean pennies, then watch them oxidize and use them to cover (or plate) an iron nail with copper! Although newer pennies contain only a small amount of copper (2. Figure!2. Electroplating involves the use of direct current to deposit metallic coatings onto workpieces. The type of metal used as anode is determined by the coating to be deposited onto the cathode. So we decided to revisit the subject with two new activities and more expert advice. Units: E in J, Q in C, V in Volts so 1 J = 1 Coulomb Volt. 5 volt batteries) to test whether higher voltages will result in faster electroplating or a heavier zinc coating on the copper. The name of the Dec 22, 2016 · 1) Electroplating metals. This technique works by first polarizing the cell at a fixed voltage and then applying a small additional voltage (or occasionally, a current) to In this experiment, NiCl 2 ionizes in the water into Ni ++ ions and two parts of Cl-ions. We apply the potential form shown in the figure. The electrolyte is tin (II) chloride, a water-soluble salt of tin. The ratio of the change in potential energy to charge is 12:1. The setup is just like experiment 1, but the washing soda is substituted with 25 ml Gain detergent. As the secondary voltage falls towards point 3, the capacitor cannot discharge its positive charge through diode D 2 The aim of this experiment was to determine how the rate of electroplating a metal could be influenced by some variable. May 17, 2021 · Electroplating: The Process & Uses in Liquid Analysis Explained. A multimeter is an instrument Parents: Body Voltage Experiment. E° = 0. Consider the circuit shown in Fig. The presented membrane is relatively hydrophobic and has its isoelectric point (IEP) at pH 4. The cell voltage of a galvanic is measured with a voltmeter. At this point, fractional Physics 401 Experiment 1 Page 3/20 Physics Department, UIUC ()2 ()22 2() 0 11 111 22 T rms o n n nn VVtdta a b T ∞∞ == ==++∫ ⎡⎤⎣⎦ ∑∑. 17:35 : still fails water break test. It works very quickly and is always well received by the students. Arc voltage (V) Arc current (A) Compressed (MPa) Spray distance (mm) NiAl Coating NiAl 33 220 0. I = The current through the electrodes. Electroplating is the most widely used method, because it is relatively easier and cheaper (Sukarelawan, 2015). Dec 28, 2015 · If you start the experiment and measure the current you should be able to work out how many grams are going to be deposited per hour assuming the current stays constant for that time. Previous studies showed optimum reactor performance on 12V [3] and 30V voltage input [6], or current density of 3A dm-2[8] and 4. The temperature of electrolyte solution was kept constant using the Lauda E100 thermostatic bath. The overpotential is the difference between the theoretical cell voltage and the actual voltage that is necessary to cause electrolysis. Use the data to plot a graph of voltage Oct 17, 2019 · Electroplating can be great fun and it has a lot of practical uses. May 30, 2020 · Electroplating was carried out with variation in deposition voltage ranging from 1 to 5 V. In this study, the electroplating wastewater (EPWW) filtration performance of a novel pH-stable NF membrane is compared against a commercial NF membrane and a reverse osmosis (RO) membrane. O. We have found that the Na + and K +, but not Cl ‑, Mg 2+, or Ca 2+, are critical to the generation of the action potentials (in the squid axon) and we have reasoned that Na + moves into the cell to depolarize it, while K + moves out of the cell to repolarize the membrane. 7kΩ). 1 MPa (0. Electricity is a form of energy that can be carried by wires and is used for heating and lighting, and to provide power for machines (Collins Dictionary, 2020). Since the wire is attached to an object, the object gets copper-coated with copper ions. Potential is an energy so potential difference is an energy difference. Repeat the experiment using a lamp instead of the resistor. The amount of silver (in Experiment 10 ~ RLC Series circuit Resonance in an RLC Series Circuit Objective: To experimentally determine the resonance frequency in a series RLC circuit and compare this to the expected resonance value. The typical emitter sheet resistivity of silicon solar cells lies in the range 30-100 Ω/ . D. 3 Polarization Measurement 65 3. Theory: The measurements of voltage, current, and resistance that you will make will be made using answers, experiment 25 electroplating ap chem lab book 10 11, lab51016 measurements using electrochemica l cells and, electrochemistry theory, introduction to electrochemistry current voltage, lecture 2 electrochemical cells definitions and principles, metal plating processes and methods of measuring surface, avoiding short circuits from Experiment #6, Series and Parallel Circuits, Kirchhoff’s Laws 1 Purpose Our purpose is to explore and validate Kirchhoff’s laws as a way to better understanding simple DC circuits 2 Introduction As we learned from the Ohm’s law experiment, an electrical circuit is any continuous path or array of paths along which current may flow. Mar 12, 2021 · In all walks of engineering, manufacturing and industrial applications, driving down costs is a key requisite, and remanufacturing is one of the best ways to achieve this. Electroplating is a process that occurs when the surface layer of one type of metal is added to another kind of metal. Electroplating classroom resources exploration of electrolytic cells aact, controlling copper electrochemical deposition ecd, lab51016 measurements using electrochemica l cells and, lab 8 measurement of voltaic cell potentials, the effect of surface area on the rate of, experiment 25 electroplating ap chem lab book 10 11, lab 8 CME312- LAB Manual Voltage Controlled Oscillator Experiment 4 Objectives : By the end of this experiment, the student should be able to: 1. 3. Theory: The measurements of voltage, current, and resistance that you will make will be made using Experiment to Examine the Relationship between Voltage, Current and Resistance. 8 volts would be the most suitable for copper electroplating. Through observation of the morphology of the samples after the electric explosion and combination with gas ionization theory, the internal influencing factors of the peak voltage and the Dec 07, 2017 · I was performing an experiment investigating the effects of solution temperature on the electroplating rate of zinc, using 0. The experimental voltage was fairly close to the predicted voltage (76. However, electroplating requires a high level of diligence, experience and precision to do correctly. Materials: 1 battery Beaker Jan 31, 2021 · Nickel is a great choice for electroplating because it requires just vinegar, salt, a cheap variable DC charger, and a few simple parts, all available from common online retailers. Electrolysis is used to electroplate objects. About this page. Then, electroplating of Cu is performed on the DLC film surface in CuCl2 solution by a three electrode-cell. Apr 25, 2017 · Electroplating is a huge business considering the number of industries that electroplate their products. Interest in electroplating began in the late 1830s, but at this time a reliable source of continuous current was lacking: large and powerful voltaic piles were built in the early years of the century but these were quite unsuitable for an electroplating process which required a low voltage applied at a steady rate over a considerable period. During electroplating a thin layer of a desirable metal is deposited onto another object. This relationship is called Ohm's Law. The amount of silver (in g) deposited by 6 A of curren Last Answer : In an electroplating experiment, mg of silver is deposited when 4 A of current flows for 2 min. In digital "movements," it is the amount of voltage resulting in a "full-count" indication on the numerical display: when the digits cannot display a larger quantity. From the geometry of the nail you should be able to estimate its surface area, and therefrom the thickness per gram. One reason could be to protect the metal from corrosion, such as galvanisation. The specific application process of the applied voltage is shown in Figure 1. Is electroplating a spontaneous reaction, or does it require energy? (Look at the voltage) 2. In this specific experiment we used 1. movements using electrochemical cells and electroplating. Adult supervision required. R. How the changing of current affects the electroplating of copper. where electroplating is carried out, and where relevant, can be applied to other processes such as anodising, hot-dip galvanising, electroless plating and general metal finishing. Nov 09, 2021 · Design of Experiment (DOE) can identify the significant factors in the process, show the correlation of each factor, and determine the optimum process parameter to achieve the targeted response (thickness). Conventional Feb 09, 2017 · Electrochemical impedance spectroscopy (EIS) is a widely used experimental method in electrochemistry, with applications such as electrochemical sensing and the study of batteries and fuel cells. Electroplating is an economically important process, often used to reduce corrosion or improve the appearance of objects. • Measure the amount of copper that was deposited in the electroplating process and determine the average current used. Turn the power off as soon as you’ve set the voltage. Also covers how plastics can be electroplated and why electroplating Discuss the meaning of electrochemistry and electroplating outlined in ‘Science Content’ with the students. Rinse the water beaker. 16-12-2021 · Download Ebook Measurements Using Electrochemical Cells And Electroplating Fundamentals of Electrochemical CorrosionElectrochemical Nov 21, 2013 · In this experiment, voltmeters were used to take readings of three different electrochemical reactions (Cu/Zn, Cu/Pb, and Zn/Pb). There are many small black 2 medium with ionic strength 0. Firstly,differentmetalionsystems (ZnII, CaII, FeIII, ZnII-AlIII, and CdIII-AlIII) were selected together with electroplating wastewater (15. 1) Figure 1: Ideal Electrical System In order to determine the current in the coil, the mglev actual electrical subsystem (see Figure 2) is equipped with a resistor Rs in series with the coil such that the voltage Vs across Rs can Aug 05, 2013 · 08/05/2013 2:19 PM. The anode consists of the plating metal. This is done by a process called electrolysis, which means that we use electricity to create a chemical reaction. Blackwood * b a Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials, School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. All solutions are 1 M. There are two types of rectifier circuits, half-wave (uses only the positive cycle of the AC signal) and full-wave (uses both cycles of the AC signal), but this experiment will focus on full-wave On the very first half cycle as the secondary voltage rises from point 1 to 2 (solid line), diodes D 2 and D 4 are forward biased and conduct, current flows through the resistor, and the capacitor is charged up to V P. Copper goes into solution at the anode as it is plated at the cathode. The voltage reading for Cu/Zn, Cu/Pb, and Zn/Pb were ELECTROPLATING 2011. 76. The concept of copper electroplating is straightforward: Submerge the wafer to be plated into an electrolyte bath, apply a current, and copper ions will migrate and deposit onto regions with a pre-existing metal seed layer. If the capacitor has a constant charge, changing the capacitance should cause the voltage to vary. If the substrate becomes negative polarized, a cathode, the reaction of ions to metal will be favored. Write the half reaction that occurs at the anode. The two metal components are electrodes, the parts of a battery where electrical current enters and leaves the battery. Plating of one metal with another metal by electrolysis is known as electroplating. Simple Current Source (SBSOURCE, Lab Chip 4) 2. Zn (s) Zn 2+ (aq) + 2e –. Electroplating and voltage experimentIdentification of an unknown metal lab answers. 532. The scientific goal of this experiment is to determine the efficiency of copper electroplating on nickel coated steel or brass. Electroplating is an interesting and exciting science experiment for kids and adults alike. Vs 1V 5V 10 V V1 V1/Vs(%) Simple Current Divider: 1. 8V voltage pulse wave forms to coat the LCO electrode with protective coating metal oxide agent. You’ll need muriatic acid, a 6-volt DC lantern battery, 2 alligator clips, a piece of copper metal, and a container large enough to submerge the metal you want to electroplate. The black and bold part indicates one pulse. Explain why your cell potential is different from the text value. The electroplating wastewater was placed in the chamber. This experiment describes one method of producing a copper For my project, I experimented with electroplating a common penny with zinc. Toifur, Moh and Ishafit, Prof. Electroplating metals. Set the output current of the power supply by setting voltage and current limits close to zero (nearly fully anticlockwise). Dec 30, 2021 · Electroplating and voltage experiment provide the necessary assurance that both the student and teacher are upholding their end of this impor tant responsibility Included is a blank Science Laboratory Safety Test as Flinn Scientific Lab Answers Gas Laws Recognizing the … Oct 27, 2004 · The voltage-dependent changes in the PSD, shown in Figure 8C, gave rise to similar voltage-dependent changes in the rms noise, indicated with dashed lines in Figure 5, B and C. One electrode is copper; the other is brass. I have even taken this into primary school. Return the meter to measure the current again and place the value in the data table 9. 303-313. During this process, hydrogen bubbles up and is released as a gas. The fresh AC electrodes are used in each experiment. PRECAUTIONS Before starting and after completion of the experiment 1. 1, with a high and positive zeta potential of +10 mV at pH 3. Electrochemical Cells And Electroplating Society. The voltage of a reaction containing two metal strips in separate aqueous solutions, with a salt bridge in between to balance charge as the reaction progressed. Hypothesis My hypothesis was that 4. When you put them back in, make sure the anode and cathode are as far apart as possible. When the experiment is run, it turns out chlorine, not oxygen, is produced at the anode. bookmark us at www cliffsnotes. People do electroplating for a number of reasons. Comparison of effects of simulated electric field interference and presence of a barrier in the nickel electroplating process to experimental data. A non-spontaneous. Plating metal may be transferred to conductive surfaces (metals) or to nonconductive surfaces (plastics, wood, leather) after the latter have been rendered conductive by such processes as coating with graphite, conductive lacquer, electroless plate, or a vaporized coating. g: chromium and nickel plating. 5 and voltage 5. Calculate the moles of copper formed. Electrolysis is used for the extraction of metals from its ores. Polished Bronze Door Numbers Jul 11, 2016 · Electroplating is the process of applying voltages to a very specific pattern on a gold-plated disk (or nickel-plated, or whatever). Electroplating is a process in which a coating of metal is added to a conductor with the help of electric current. Similar time constants for any of the various interfacial electrochemical … Experiment 11 Electrochemical Cells and Oct 09, 2019 · Controlling this charged layer via pulsed electrodeposition is a remedy and one of the primary reasons for the application of differentiated electroplating voltage waveforms. You can measure this back voltage at the electrodes when the battery has been disconnected. Measure I, Ri, Vi, and Req. S. Experimental 1. (Adult supervision and chemical safety equipment required. Z. Objective: Electroplating of copper on a copper plate Apparatus Required: ADVERTISEMENTS: A glass plating tank with plastic lid, voltmeter, ammeter, copper plates, rheostat, one way key, piece of sand […] For my project, I experimented with electroplating a common penny with zinc. The two most prevalent chromium forms found in plating industry waste water are […] Electroplating is an energy intensive process. To replace worn or damaged human joints by synthetic ones, doctors need strong, light, and resistant materials. 17. 2 A to 0. Through the use of low voltage, the brush dipped in plating solution allows for localized Prelab: 1. 34. This experiment devoted to fifth. Mar 08, 2020 · I am doing an experiment that aims to determine if the rate of electroplating changes with the temperature. It serves as a succinct summary of the ways a voltage (or emf) may be generated by a changing magnetic environment. Note that the integration is over one period. At the frequencies of interest the capacitors in the circuit of Figure 7-1 will have an insignificant impedance and are therfore considered to be an AC To provide a basis for comparing the results of one experiment with another, the following set of standard-state conditions for electrochemical measurements has been defined. The aim of this work was to utilize optimized acid leaching to reduce the toxicity of heavy metals in EPS. The current should read somewhere between 0. Set the output voltage set at 20 V (no-load) and the short-circuit current limit to 80 mA. Discuss the terminology relevant to this activity. Chemical treatments are tested to produce a Electroplating and voltage experiment. Electrochemical behaviors of Janus Green B in through-hole copper electroplating: An insight by experiment and density functional theory calculation using Safranine T as a comparison on when the voltage across it goes above zero), we see zero current when v D is negative and infinite current as soon as v D tries to go positive. The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating. That only resulted in some deposit on the stainless that needed to be scrubbed off. Try the experiment. 10 V at room temperature. In potentiostatic mode, a small alternating voltage is applied and the AC response is measured. : 5 Lab. This activity will explore two examples of electroplating. In recent years, the "greenhouse effect" has garnered increased attention in the news media, academia, the government, and the general public. Theoretical: E˚ = +0. 1 M half-reaction. Electrochemical Cell Voltage might be separating a metal from molten alloy or electroplating an object submersed in a metal cation Trial 2 of experiment A Electroplating was first figured out by Michael Faraday. I also want to keep every other variable the same, which means the voltage across the rods, the concentration of the solution and the current that goes A STUDY OF ELECTROPLATING PROCESS THROUGH EXPERIMENT AND SIMULATION 439-4 4. The on time for each 1. Chemical precipitation is the Apr 14, 2020 · Electroplating household metals is the process of coating them with a different metal, and you can easily do it at home. Aug 13, 2018 · Tech Brief: Elements of Electroplating. 2. 4)Production of chemical compounds. It also seems that the use of similar batteries can be safely placed into ancient Egypt, where several objects with traces of electroplated precious metals have been found at different locations. MATERIALS This process, which is related to electroplating is often referred to as selective plating, or brush plating. His work in this fi eld was well along by the end of 1807 and included indications that one metal could be deposited upon another. • Calculate a value for Avogadro’s number and compare it to the accepted value. Chemical Engineering Research and Design, Volume 89, Issue 2, February 2011, Pages 136-147. Electrodeposition and Electroplating - Electroplating Beaker Materials. In this experiment we will be putting these concepts to test by attempting to copper-coat nickels and quarters. Tony Arana, Southwest Sales Manager for SIFCO ASC explains selective electroplating's role in remanufacturing, and how this technique can build components back to original specifications. The source DC voltage was set to 500 V. You can pass electric current through an electric cell, called an electroplating bath, to deposit one metal on another. Gold, Sep 06, 2021 · Gold Electroplating : Gold Plating Kit - Brush Plating (Complete Start-Up Kit & Gold Solution) - YouTube. Build the circuit as seen in Figure 3-1 c. 2 Preparation of Substrate 64 3. Finds application in preventing metals from corrosion. Start the experiment; Collect Data 5. Depending on the desired function or decorative purpose, we offer the following electroplating metal finishes: Chrome. The zinc is in the galvanization on the nails, and the pennies are actually copper-plated zinc. Supervisor: Munther N. However, the first solid historical reference Nov 01, 2013 · The actual electroplating process consists of connecting a piece of copper to the positive terminal of a 6 volt battery. It was first achieved through a silver-cyanide solution patented by the Elkington brothers in 1840 [5]. They are used as source for battery charging purpose. Shortly after, Sir Humphry Davy became engaged in electrochemical research. At present, there is no suitable physical and mathematical model to describe the process and results of rock breakage in EPB, and the Aug 05, 2013 · 08/05/2013 2:19 PM. The one variable is the copper II sulfate source. The object to be plated, such as a metal pan, is connected to the negative terminal of the power supply. , Taufiqurrahman and . Experiment no. Material requirements 1–Most of the coating is a single metal or alloy. Electroplating experiment lab report pdf. During electroplating, the object to be plated is attached to the negative post of a power source, causing the object to gain a Electroplating is a coating method whereby a component to be plated is set as a cathode into an electrolyte solution containing metal salts. What You Need: 6-volt or 9-volt battery Figure!2. F (electromotive force) is known to be the force that drives the current thhrough the circuit. The process which is used in electroplating is electrodeposition. Possessing an easy, economical way to monitor the condition of the functionality (operability) of a person's bio-electric system—the collection of bio-electric phenomena present in and around a physical body that is used to assist in that body's perpetuation—might help them by affording to them a way to determine the effectiveness of any bio-electrically Faraday’s Law 1 Experiment 8 Copper Electroplating And April 19th, 2018 - Faraday’s Law 1 Experiment 8 Copper Electroplating And Faraday’s Law 1 An Electrochemical Cell Is Constructed To Make Your Mass Measurements To The' 'lab51016 measurements using electrochemica l cells and voltage potential of only 0. In typical usage, the current is electroplating and Ti lift-off applications. Apr 14, 2020 · Electroplating household metals is the process of coating them with a different metal, and you can easily do it at home. 1 Experimental Works 63 3. Plasma source gas Electroplating and voltage experiment. Let RREF=5 kΩ. voltage from the outlet to a DC voltage that can be used to power many household appliances. Electroplating Of Copper MOIZUDDIN QURESHI & SYED ALI 2. I set the voltage to 5 volts, and the current to around 2 amps. 98, No. 4. e HTlc was prepared by the coprecipitationmethod. In this example the copper sulfate is 50 mM 2. Metabolic changes in rapidly dividing cancer cells are closely 2 of 7 Experiment 10 Current Sources and Voltage Sources 3. Jul 01, 2011 · In the present experiment effect of electroplating industrial effluent chromium on the behavioral responses of freshwater air-breathing cat fish Mystus cavasius was studied. Equipment: Bread board, variable DC power supply, resistors (15kΩ, 22kΩ, 47kΩ, 68kΩ, and 1MΩ), multi-meter, and ammeter. In performing the experiment, measured values will be used for the emfs and resistances. Write the half reaction that occurs at the cathode. sulfite plating in the gold electroplating bin on the shelves. The flow of direct current causes one of the electrodes (the anode) to dissolve and the other electrode (the cathode voltage in a cathode-ray tube which deflects the electron beam to the edge of the indicating screen. , a spoon) is made from the cathode of an electrolytic cell. 1 M. Measurements with these solutions will lead to values of the formal potential for the Ag+ + e = Ag, μ = 0. 15. This will remove any remaining oxidation. Or, So, When I = 1 and t=1 m=Z. The voltage reading for Cu/Zn, Cu/Pb, and Zn/Pb were experiment. Replace the Copper cathode with a clean metal object such as a Door Key, Spoon etc. Compared here are variations of thickness with respect to time and voltage for center and offset positions. Construct this circuit. The copper dissolves and shoots over to the key and gets stuck as a thin layer onto the metal key. Jul 11, 2016 · Electroplating is the process of applying voltages to a very specific pattern on a gold-plated disk (or nickel-plated, or whatever). 5 A). All gases have a partial pressure of 0. Electroplating is a procedure whereby a thin layer of gold and silver is put on a cheaper metal, and the final product is available at an affordable cost. At the same time, it is the most economical method for preparing Mg-RE alloys and could be easily implemented on a large scale as well as it could be employed over a large temperature range