MST 557 EXPERIMENT 1 IV CHARACTERISTICS PDF

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FACULTY OF APPLIED SCIENCE

AS240- BACHELOR OF SCIENCE (HONS) MATERIALS TECHNOLOGY

MST557- ELECTRONIC AND SEMICONDUCTOR MATERIALS

PREPARED BY : NUR AINA AMIRAH BINTI MAT KAMARUDIN (2019455092)

PREPARED FOR : DR NUR AIMI JANI 3RD JULY 2021

EXPERIMENT 1-THE I-V CHARACTERISTICS OF ELECTRICAL COMPONENTS

OBJECTIVES a) To study the current-voltage relationship in circuits containing various resistive components. b) To measure the values of resistance of the same materials. c) To understand the principal of Ohm’s Law.

INTRODUCTION The unit of current is the Ampere, which is equal to a (Coulomb/second). It flow in the direction of the current is the same as the direction of movement of positive charges in electric field. In a metallic conductor, such as a wire, the only mobile particles are negatively charged electrons, which move in an opposite direction. The relationship between the voltage, current, and resistance in a metallic conductor is given by Ohm's law. It states as follows: If the temperature and other physical conditions of a metallic conductor are unchanged, the ratio of the potential difference across the conductor (V) to the current (I) is a constant. This constant ratio (R) is the resistance of the conductor. R= V/I If potential difference is measured in Volts and current is in Amperes, resistance will be in Ohms (Unit of resistance, equal to one Volt per Ampere). The resistance of a metallic conductor depends only on its length, the area of cross-section, the material of the conductor and its temperature. It does not depend on either V or I. At a given temperature R= ρ L/Α, Where ρ, L and A are resistivity, the length, and cross sectional area of the resistor.

SUMMARY OF FINDING The relationship between current through, and voltage across, a component is called the currentvoltage (I-V) characteristic. Resistor at constant temperature The voltage is exactly proportional to the current for a given resistance. When the quantity of energy is doubled entering the resistor, the current across the resistance is twice as quickly. This connection is known as the law of Ohm and is valid because of the resistance of the resistor (because the temperature does not change) A resistor is an ohmic conductor

Circuit with a battery, variable resistor, resistor, ammeter and a voltmeter connected in parallel to the resistor

Graph plotting potential difference against current for a fixed resistor. Line is directly proportional Filament Lamp The current does not rise at the same pace as the voltage in a filament bulb. Doubling energy does not cause the current to double as quickly. The more energy the bulb gets, the harder the current flows - the resistance of the bulb rises. As the voltage rises, the thin wire within the bulb, the filament, also grows. The increased vibrations of the ions in the filament due to the higher temperature make passing electrons difficult.

Circuit with a battery, variable resistor, lamp, ammeter and a voltmeter connected in parallel to the lamp

Graph plotting potential difference against current for a filament bulb. Line is an upward curve that levels out and starts to dip as potential difference increases Diode A semiconductor diode only permits a single passage of current. If the potential difference is adjusted to attempt to push the current the incorrect direction (sometimes termed the reverse

bias), then no current flows since the resistance of the diode remains extremely high. Current flows only if the diode is forward-oriented. When the diode is biassed, the resistance of the diode is extremely high for low potential differences, typically up to 0.7 V, but at larger potential differences, resistance falls rapidly and current starts flowing.

Circuit with a battery, resistor, variable resistor, diode, ammeter and a voltmeter connected in parallel to the diode

Graph plotting potential difference against current for a diode. Line is horizontal on the x-axis for a part, and then it curves upwards sharply Variation of resistance in a thermistor and an LDR The thermistor resistance changes with temperature. The resistance diminishes as the temperature rises.

The resistance of an LDR changes with the intensity of light. The lighter the event on the LDR, the less resistance.

Material and Shape Dependence of Resistance

Figure 1. A uniform cylinder of length L and cross-sectional area A. Its resistance to the flow of current is similar to the resistance posed by a pipe to fluid flow. The longer the cylinder, the greater its resistance. The larger its cross-sectional area A, the smaller its resistance. The strength of an item relies on its form and the substance it consists of. The cylindrical resistor in Figure 1 is simple to analyse and therefore the resistance of complex forms may be understood. As one would anticipate, the electric resistance of the cylinder R is exactly proportional to its length L, comparable to the resistance of a fluid flow pipe. The longer the cylinder, the more collisions the atoms carry. The higher the cylinder diameter, the more current it can transport (again similar to the flow of fluid through a pipe). Indeed, R is inversely proportional to the cross-sectional area A of the cylinder.

For a certain form, the resistance relies on the material the item is made of. Various materials provide varying load flow resistance. We define the resistivity − of a material to directly proportionate the resistance R of an item to μ. Resistivity μ is an inherent characteristic of a material, regardless of form or size. The resistance R of a standard cylinder of length L, crosssectional area A and composed of a resistive material , is R=pL/A

Table 1. Resistivities ρ of Various materials at 20º C

Table 1 gives representative values of ρ. The materials mentioned in the table are classified by large resistance groups into categories of conductors, semiconductors and insulators. Drivers have the lowest resistivity and insulators the greatest; semiconductors have intermediate resistivity. Drivers have variable but high free densities, while most isolation charges are tied to atoms and not free to move. Semiconductors are intermediate, with much less free charges than drivers, but their characteristics are highly dependent on the kind and the quantity of impurity in the semiconductor. These special characteristics of semiconductors are used in contemporary electronics as discussed in subsequent chapters.

PRINCIPLE OF OHM’S LAW The Law of Ohm explains how a substance flows at various voltage levels. Some materials like electric wires have minimal current flow resistance and this kind of material is known as a conductor. If, for example, this driver is positioned directly across a battery, a lot of current will flow. In some cases, another substance may obstruct the current flow, yet nevertheless allow it. These components are frequently termed resistors in electrical circuits. However, some materials practically leave no current and these materials are known as insulators. Ohm's Law says that the flow of the current into a circuit is directly proportional to the applicable potential difference and inversely proportional to the circuit resistance.In other words, the current will also double simply doubling the voltage across a circuit. However, the current will decrease by half if the resistance is doubled. The resistance unit is measured in Ohms in this mathematical connection. Current = electrical charge flow, electron movement along a wire

Again, we have to operate with a ratio. We can decrease the resistance or raise the voltage to boost current. This seems correct since we believe that providing greater pressure, with less resistance, is the method for more electrons to move. When you measure a circuit and observe a decrease in current, something has happened and the law of Ohm informs us that the voltage has fallen or the resistance is rising. Resistance = resistance to electric charging flow (current)

Normally, but not always, you want to have lower resistance so that more electrons can pass through your circuit. In this instance, Ohm's Law tells us that a decreased voltage will provide a lower resistance value. The resistance will likewise diminish as the current increases or you may overcome resistance by introducing additional electron flow. There are situations in which you wish to enhance strength and the calculation indicates that we would lower the current or raise the voltage in this scenario

Voltage = electrical differential between two locations, energy potential V=IxR If we look at voltage as a kind of pressure differential, we can see that either the increase in current (flow) or the increase in resistance (block) causes a larger pressure difference. In the current instance, additional electrons are like traffic jams and increase voltage in the same area. If the route (meaning a greater resistance) is limited for a given number of electrons, the voltage increases, as is the case for an autobahn with a lane or two closed. Power Equation (watts) Everyone knows something, at least if you have ever replaced a light bulb, it's the word Watt. The Watt is the unit for measuring electrical power. Power in resistance circuits and comparable relationships is closely linked to Ohm's Law.

where P = Power (Watts), V = Voltage (Volts), R = Resistance (Ohms), I = Current (Amperes) Although the formulae seem identical, several complicated relationships are shaped. What we can see is that the resultant power value would be dictated by the resistance for a given voltage and current. The labelled Power Level (or watts) for the components of a circuit may tell us the combination of the resistance load and the amount of current drawn. Ohm's law triangle

To assist recall the formula, you may use a triangle with a horizontal side and the top as a pyramid. This is commonly known as the triangle of the Ohm Law.

The letter V in the top corner of the Ohms law triangle, the letter I in the left corner and the lower right corner, R in the left corner.

CITED REFERENCES BBC. (n.d.). Current-voltage (I-V) characteristics for components - Current, potential difference and resistance - Eduqas - GCSE Physics (Single Science) Revision - Eduqas - BBC Bitesize. BBC News. https://www.bbc.co.uk/bitesize/guides/zgbwpbk/revision/3. OpenStax. (n.d.). Physics. Lumen. https://courses.lumenlearning.com/physics/chapter/20-3resistance-and-resistivity/. Keim, R. (2015, June 21). Measuring Resistance, In Circuit and Out - Technical Articles. All About Circuits. https://www.allaboutcircuits.com/technical-articles/measuring-resistancein-circuit-and-out/. Poole, I. (2021, February 16). What is Ohms Law - key details formula equation. Electronics Notes. https://www.electronics-notes.com/articles/basic_concepts/resistance/what-is-ohmslaw-formula-equation.php. Ohm's Law - The principle of Electronic Circuits. Make Math a Game. (2018, March 30). http://www.makemathagame.com/everyday_math/ohms-law-circuit-math/.

EXPERIMENT 2- RESISTOR

INTRODUCTION Resistor are known as a passive two-terminal electrical component that are been implement as electrical resistance as a circuit element. It was used in electronic circuit to reduce the current flow as well as to divide the voltages. The electrical function of a resistor are specified by its resistance where common commercial resistor are manufactured over a range of more than nine orders of magnitude. The nominal value of resistance falls within the manufacturing tolerance, indicated on the component. The behavior of an ideal resistor are dictated by the relationship specified by the Ohm’s Law: V = I.R It state that the voltage (V) across a resistor are proportional to the current thus the constant proportional are the resistance. It also state that if the potential difference are measured in Volt and the Current in Amperes, the resistance will be in resistance.

OBJECTIVE To determine the equivalent resistances of resistors connected in series and parallel.

SUMMARY OF FINDING To begin, we shall examine the characteristics of resistors linked "in series." Figure 1 depicts two resistors in series (a) and the analogous circuit with a single resistor (b), as described in the lecture. Remember from class that series resistors "see" the same current. When water is sent via two pipes of various diameters linked in series, each gets the same quantity of water, and the water can not be divided. For resistors in series, the corresponding resistance is Req = R1 + R2.

If N resistors are connected in series, the equivalent resistance is given by Req = Σ Ri (for i=1,2,3,...,N) OR Req = R1 + R2 + R3 + ... + RN. In the second part of this lab we'll hook them together as in Figure 2.

These resistors are paralleled. In the series, they were linked one after the other, but in parallel, they were'side by side'. When resistors are connected in series, the current coming from the battery has the option of which branch to choose. Due to the difference in resistance, water flowing into two pipes will flow more freely via the bigger pipe (lower resistance) (greater resistance). Parallel resistors "see" different currents yet experience the same potential difference (voltage). To calculate equivalent resistance in class, we utilised this characteristic of resistors in parallel. For resistors in parallel, the equation is simpler. Instead of adding resistance, we compute

Remember that after this computation, you will have 1/Req. Flip it over to receive Req! An example: If R1 = 270 and R2 = 330, we get Req as follows:

So, Req ≈148Ω

Similarly to resistors in series, we may extend this equation. We may extend this rule to any number of resistors:

STANDARD RESISTOR COLOR CODE

This colour code is for "standard" resistors with a rating of 5 percent or 10 percent accuracy or tolerance. In other words, its value is guaranteed to be within 5% or 10% of its labelled value.Their colours, from left to right, are read. The first two colour strips indicate the first two important numbers of the resistor value. The third band's colour indicates a multiplier of 10N, where N is the colour value.The fourth band is usually gold or silver, indicating a tolerance of 5% or 10%. Gold or silver is never the first band. To properly read a resistor value, the gold or silver band must be on the right. For example, a resistor with a red first strip, yellow third strip, orange and gold fourth strip has a value of 24,000 ohm (24 x 103) and a 5% tolerance. RESISTANCE MEASUREMENT

Resistance levels will be measured using a DMM. A first-time user's guide may be provided by the teacher. Check to discover whether the instrument has an instruction manual. The DMM may include function and range of buttons and/or switches. Turn on "OHMS." Some metres may automatically adjust the range based on the number of significant digits shown. You should obtain at least three meaningful digits. Make measurements as described below and experiment with range settings. Each resistor's power rating is dictated by its size. Smaller dimensions equate to less power handling. A variety of resistor sizes should be accessible in the lab. 14 watts is a typical power rating. An overheated 14-watt resistor may burn out.

CITED REFERENCES Experiment 1. Electrical Resistance and the Resistor. (n.d.). http://www.zapstudio.com/Assets_Publish/EE_for_Tech_2nd_Ed_Lab_1.pdf. Experiment 4 ~ Resistors in Series & Parallel. (n.d.). http://www.umsl.edu/~physics/files/pdfs/Electricity%20and%20Magnetism %20Lab/Exp4.SeriesParallel.pdf. Resistance and Ohm's Law. (n.d.). https://www.d.umn.edu/~djohns30/phys1002-labs/Lab %203%20Resistance%20&%20Ohm's%20Law.pdf. sample lab report. lab exercise. (n.d.). http://www.manufacturinget.org/wpcontent/uploads/2011/09/Sample-Lab-Report.pdf. Wikimedia Foundation. (2021, July 11). Resistor. Wikipedia. https://en.wikipedia.org/wiki/Resistor.

EXPERIMENT 3- DIODE OBJECTIVES 1. To study the flow of current in a diode of forward or reverse bias 2. To determine the operating voltage of diode

INTRODUCTION Diode is one of simplest electronic device. The function of diode is to allow an electric current to pass in one direction (called the diode’s forward direction), while blocking it in opposite direction (reverse direction). Semiconductor devices such as diodes consists of p type and n type semiconductors joined together. P-type (anode) diodes is where holes are the majority carriers and electrons are the minority carriers. P-type semiconductors are created by doping an intrinsic semiconductor with acceptor impurities. Meanwhile n-type (cathode) is where electrons act as majority carriers and holes act as minority carrier. N-type semiconductor are created by doping an intrinsic semiconductor with donor impurities. These are schematic symbol of a diode:

When n-type and p-type semiconductors are in contact, the unequal concentration of electrons and holes result in the diffusion of electrons across the junction; electrons move from the n-side to p-side and holes from the p-side to the n-side until equilbrium established. The potential difference, V or a barrier potential builds across the junction, which tends to inhibit further diffusion. In equilbrium, the n-side is at higher potential than p-side. With in the junction, there are very few charge carriers of either type, so the resistance is very high.

A semiconductor p-n junction can be used as simple current rectifier. If we connect the positive terminal of the battery to the p-side, the potential across the junction will be lowered. The diffusion of electrons and holes through the junction will increase as they try to reestablish equilibrium, resulting in flow current or we called it as forward biased. On the other hands, if the battery is reversed, the potential difference across the junction will be increased, inhibiting further diffusion. SUMMARY OF FINDING Types of Diodes: 

Zener diode - used for voltage regulation.

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Schottky diode - used as rectifiers in high-frequency circuits.

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Varactor diode - functions as a variable capacitor.

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Avalanche diode - used for RF and microwave generation.

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Silicon Controlled Rectifier (SCR) - used as controllers. For example, to set duty cycles.

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Schockley diode - used as a trigger switch for SCRs.

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PIN diode - used as RF switch and also for detecting X-rays and gamma rays.

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Gunn diode - used to generate signals in the microwave range.

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Crystal diode

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Laser diode - used in optical devices; such as CDs, DVDs and Blu-ray recorders and players.

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Light Emitting Diode (LED) - used in displays, as indicators and for lighting.

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Photodiode - the inverse of the LED. Incoming light is converted to electrical current.

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Tunnel diode - used as a very high-speed switch (in nanosecond range).

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Peltier Diode - used in thermal applications for heating or cooling.

THE TWO REGIONS OF A DIODE The two semiconductor areas in a diode (P and N). However, you must also distinguish between the sides or semiconductor areas. The cathode is on the right and the anode is on the left in the schematic representation of a diode. Think of the anode side of the schematic symbol as an arrow indicating normal current flow, positive (+) to negative (-). (-). A diode allows current to flow in the arrow's direction. Consider the vertical line on the cathode side as a huge minus sign (-), indicating which side of a diode is forward biassed. Hydraulic Check Valve Analogy Diode behaviour is similar to that of a hydraulic...