Week 4 and 5 - Dielectrics PDF

ELECTRICAL ENERGY LEARNING OBJECTIVES: Calculate the net electric force on a point charge exerted by a system of point charges Solve problems involving electric charges Describe what happens in this simulation John Travolta ge - Static El ectricity - PhET Interactive Simulations ( colorad...

ELECTRICAL ENERGY LEARNING OBJECTIVES: Calculate the net electric force on a point charge exerted by a system of point charges Solve problems involving electric charges Describe what happens in this simulation John Travolta ge - Static El ectricity - PhET Interactive Simulations ( colorado.edu ) ATOMS  The structure of atoms can be described in terms of three particles:  the negatively charged electron  the positively charged proton  the neutrally charged neutron ATOMS  The protons and neutrons in an atom make up a small, very dense core called the nucleus.  The protons and neutrons are held within stable atomic nuclei by an attractive interaction, called the strong nuclear force. ATOMS  The negatively charged electrons are held within the atom by the attractive electric forces exerted on them by the positively charged nucleus. ELECTROSTATIC FORCE  Attractive or repulsive force between two electrically charged objects. Electrostatics  The interactions between electric charges that are at rest. ATOMS  The masses of the individual particles, to the precision that they are presently known, are: Proton = 1.672621898(21) x 10-27 kg Neutron = 1.674927471(21) x 10-27 kg Electron = 9.10938356(11) x 10-31 kg ATOMS ELECTRICAL ENERGY ATOMS  In a neutral atom the number of electrons equals the number of protons in the nucleus, and the net electric charge is exactly zero. Atomic Number  Number of protons or electrons in a neutral atom of an element. q=0C O + - - q = -1.60 x 10-19 C O + - q = 1.60 x 10-19 C O + - q = (-1.60 x 10-19 C)(2) q = -3.20 x 10-19 C O + - - ATOMS  If one or more electrons are removed from an atom, what remains is called a positive ion.  A negative ion is an atom that has gained one or more electrons.  This gain or loss of electrons is called ionization. Young, H. D., & Freedman, R. A. (2019). University Physics with Modern Physics in SI Units (15th ed.). Pearson. How do objects get charged? METHODS OF CHARGING 1. Charging by friction 2. Charging by conduction. 3. Charging by induction. Charging by friction  CHARGING BY FRICTION  Occurs when objects are rubbed against each other, causing a transfer of electrons. Toppr Answr. (n.d.). Charging by friction [Illustration]. https://www.toppr.com/ask/content/concept/charging-by- induction-209363/ TRIBOELECTRIC SERIES  List of objects and their tendency to give up or take electrons when charged by friction with other objects in the same list. StaticWorx Groundsafe ESD Flooring. (n.d.). GLOSSARY: TRIBOELECTRIC SERIES [Illustration]. https://kb.staticworx.com/esd_glossary/triboelectric-series/ LAW OF CHARGES  Two positive charges or two negative charges repel each other.  A positive charge and a negative charge attract each other. “Like charges repel while unlike charges attract.” CONSERVATION OF CHARGE  The algebraic sum of all the electric charges in any closed system is constant.  In any charging process, charge is not created or destroyed; it is merely transferred from one body to another. CHARGING BY CONDUCTION Conduction  Transfer of electrons from a charged object to another object by direct contact.  Conductors can be charged by conduction. Charging by Conduction http://www.physicsclassroom.com/Class/estatics/ u8l2c1.gif CONDUCTORS & INSULATORS Conductors  Materials whose electric charges are free to move within. Insulators  Materials in which electric charges are NOT free to move within. Young, H. D., & Freedman, R. A. (2019). University Physics with Modern Physics in SI Units (15th ed.). Pearson. Young, H. D., & Freedman, R. A. (2019). University Physics with Modern Physics in SI Units (15th ed.). Pearson. CHARGING BY INDUCTION Induction  Movement of electrons to one part of an object by the electric field of another object. In the induction process, the opposite type of charge is produced.  Charging a metal ball by induction Young, H. D., & Freedman, R. A. (2019). University Physics with Modern Physics in SI Units (15th ed.). Pearson. Charging by Induction http://www.physicsclassroom.com/Class/estatics/ u8l2b1.gif WRITTEN WORK: Conceptual Essay INSTRUCTIONS: 1. Visit and explore this simulation link: https://phet.colorado.edu/sims/html/balloons-and-static-electri city/latest/balloons-and-static-electricity_en.html 2. Make sure to check the “Show all charges”. 3. Rub the balloon on the sweater and then put the balloon close to the wall. 4. Put the balloon in the middle of the sweater and wall, and observe to where the balloon would go to. 5. Answer the guide questions on the next slide (be guided by the rubrics) WRITTEN WORK: Conceptual Essay GUIDE QUESTIONS: (accumulate the answers in the questions in 1 whole paragraph/essay) 1. What charge was accumulated by the balloon? 2. What happens when the balloon has accumulated all the electrons from the shirt? What is its reaction with the wall? With the shirt? Why is it so? 3. How can you explain the phenomenon called “lightning” from this simulation?  Area of assessment 5 4 3 2 Content Presents ideas in an Presents ideas in a Ideas are too Ideas are vague original manner. consistent manner. general or unclear Content is relevant Content is relevant and accurate. but with some inaccuracies. Organization Strong and Organized Some No organized beginning/mid/end organization; organization; beginning/middle/e attempt at a lack nd beginning/mi beginning/mid ddle/end dle/end Observation Writing shows keen Writing shows Writing Writing shows observation adequate shows little no observation observation observations ELECTRICAL ENERGY What is the charge of this atom? q=0C O + - What is the charge of this ion? - q = -1.60 x 10-19 C O + - What is the charge of this ion? q = 1.60 x 10-19 C O + What is the charge of this ion? - q = (-1.60 x 10-19 C)(2) q = -3.20 x 10-19 C O + - - COULOMB’S LAW  the electric force between two charges is proportional to the product of the two charges  the electric force is inversely proportional to the square of the distance between the charges use the distance between the centers of the spheres as r kc = 8.9875 × 109 N.m2/C2. SAMPLE PROBLEM The electron and proton of a hydrogen atom are separated, on average, by a distance of about 5.3 × 10 -11 m. Find the magnitude of the electric force. q1 = -1.60 x 10-19 q2 = 1.60 x 10-19 C C 5.3 × 10 -11 m SAMPLE PROBLEM Given: r = 5.3 × 10 -11 m q1 = -1.60 x 10-19 C q2 = 1.60 x 10-19 C k = 8.9875 × 109 N.m2/C2 F =? Solution: SAMPLE PROBLEM If 2 point charges have 5 C and 4.5 C of charge respectively, and they are being pushed away from each other by a force of 5.68 N, how far apart are they? q1 = 5 C q2 = 4.5 C F = 5.68 N SAMPLE PROBLEM Given: q1 = 5 C Solution: q2 = 4.5 C F = 5.68 N k = 8.9875 × 109 N.m2/C2 Solution: r=? SAMPLE PROBLEM The electron and proton of a hydrogen atom are separated, on average, by a distance of about 5.3 × 10 -11 m. Find the magnitude of the electric force. q1 = -1.60 x 10-19 q2 = 1.60 x 10-19 C C 5.3 × 10 -11 m SAMPLE PROBLEM Given: r = 5.3 × 10 -11 m q1 = -1.60 x 10-19 C q2 = 1.60 x 10-19 C k = 8.9875 × 109 N.m2/C2 F =? Solution: SAMPLE PROBLEM A 5 μC charge is 5 μm far from a -5 μC charge and 10 μm from a 5.1 μC charge. What is the net force acted on the -5 μC charge and 5.1 μC charge? (Assume that all 3 charges lies on the x-axis) SAMPLE PROBLEM F2net = ? 5 μm F3net = ? q1 = 5 q2 = -5 q3 = 5.1 μC μC μC 10 μm F2net = F2,1 + F2,3 SAMPLE PROBLEM F2net = ? 5 μm F3net = ? q1 = 5 q2 = -5 q3 = 5.1 μC μC μC 10 μm F2net = F2,1 + F2,3 F3net = F3,2 + F3,1 SAMPLE PROBLEM Given: q1 = 5 μC = 5 x 10-6 C q2 = -5 μC = -5 x 10-6 C q3 = 5.1 μC = 5.1 x 10-6 C k = 8.9875 × 109 Nm2/C2 F2net = ? F3net = ? SAMPLE PROBLEM Solution: SAMPLE PROBLEM Solution: SAMPLE PROBLEM Solution: The net force acting on the second charge (q2) is 1.80 𝑥 Conclusion: 108 𝑁 to the East. SAMPLE PROBLEM Solution: SAMPLE PROBLEM Solution: SAMPLE PROBLEM Solution: The net force acting on the third charge (q3) is 6.88 𝑥 Conclusion: 109 𝑁 to the West. SAMPLE PROBLEM A Boron ion with 3 electrons is 4 μm away from a point charge with 4.32 μC of charge. If the second point charge is 8.77 μm away from an ion with a charge of -43.34 μC, what is the direction of the net electric force on the Boron ion? What is the net electric force on the -43.34 charge? (assume that all 3 point charges lies on the x-axis) SAMPLE PROBLEM A Boron ion with 2 electrons is 4 μm away from a point charge with 4.32 μC of charge. If the second point charge is 8.77 μm away from an ion with a charge of -43.34 μC, what is the direction of the net electric force on the Boron ion? What is the net electric force on the - 43.34 μC charge? (assume that all 3 point charges lies on the x-axis) q1 q2 q3 4 μm 8.77 μm SEATWORK 5: Solving Exercise Part A (5 pts each number) 1. If a Helium ion has 4 electrons and it is 500 cm apart from a 6.98 C point charge, what is the electric force that they will exert on one another. 2. 2 point charges both have -43 C of charge. If they repel each other with a force of 5698 N, how far apart are they? 3. If an ion+ with one missing electron and an ion- with 2 excess electrons are 4.23 x 104 mm apart, what is the electric force? 4. 2 point charges are attracted to each other by a force of 50 kN. If they are 0.0041 km apart, what are their charges? SEATWORK 5: Solving Exercise Part B 1. An electron is 6.70 μm far from a Hydrogen ion that has 3 excess electrons. What is the net electric force on the Hydrogen ion if it is 6 μm far from a Helium ion that has 3 electrons. 2. An ion with 0.1 μC is 1 cm far from a charge that has -0.2 μC. If another charge which has 0.3 μC is 8 cm far from the 0.1 μC charge, what is the net electric force acted on the 0.3 μC charge? SEATWORK 5: Solving Exercise Part B 1. An electron is 6.70 μm far from a Hydrogen ion that has 3 excess electrons. What is the net electric force on the Hydrogen ion if it is 6 μm far from a Helium ion that has 3 electrons? 2. An ion with 0.1 μC is 1 cm far from a charge that has -0.2 μC. If another charge which has 0.3 μC is 8 cm far from the 0.1 μC charge, what is the net electric force acted on the 0.3 μC charge?  Electric force per unit charge experienced by a charge at a certain point. 𝐹 𝐸= 𝑞  The magnitude of the electric field at the field point is given by: 𝑞 𝐸 =𝑘 𝑐 2 𝑟  The electric field of a point charge always points away from a positive charge.  The electric field of a point charge always points toward a negative charge. SEATWORK 5: Solving Exercise Part B 1. An electron is 6.70 μm far from a Hydrogen ion that has 3 excess electrons. What is the net electric force on the Hydrogen ion if it is 6 μm far from a Helium ion that has 3 electrons? 2. An ion with 0.1 μC is 1 cm far from a charge that has -0.2 μC. If another charge which has 0.3 μC is 8 cm far from the 0.1 μC charge, what is the net electric force acted on the 0.3 μC charge? SAMPLE PROBLEM A Boron ion with 3 electrons is 4 μm away from a point charge with 4.32 μC of charge. If the second point charge is 8.77 μm away from an ion with a charge of -43.34 μC, what is the direction of the net electric force on the Boron ion? What is the net electric force on the -43.34 charge? (assume that all 3 point charges lies on the x-axis) CURRENT, RESISTANCE AND ELECTROMOTIVE FORCE Objectives  Distinguish between conventional current and electron flow  Describe the ability of a material to conduct current in terms of resistivity and conductivity  Solve problems involving the relationship between resistance, voltage, and current CONDUCTOR VS INSULATOR How conductors conduct electricity? Formative: Tell if the following materials are conductors or insulator 1. Copper 2. Rubber 3. Glass 4. Pure water 5. Au 6. Ag 7. Beryllium 8. Hair 9. Human skin 10.Paper Explore the Circuit Construc simulatio tion Kit: AC (col orado.edu) n Current Defined as the time rate of flow of electric charge Measured in Amperes (A)  Voltage Also known as electric potential difference the amount of work it would take to move a charge between two points divided by the value of the charge It has the unit volt (V) which Resistance The opposition to the flow of charge because of the collisions within the conducting material Can be obtained using Ohm’s Law Measured in Ohms (Ω) OHM’S LAW  Ohm’s Law Describes the relationship between voltage, current, and resistance Wattage (Electric Power) When current exists in a circuit, work is done to overcome resistance and power is expended Sample Problem Sample Problem A circuit has a resistance of 18 Ω and a current of 15 A, what is the rate of energy per Coulomb? Given: Solution: R = 18 Ω I = 15 A V=? Sample Problem What is the current produced by a voltage of 300 V through a resistance of 0.5 Ω Given: Solution: V = 300 V R = 0.5 Ω I=? Sample Problem A 12 V socket produces 120 Coulombs of charge per second. What is the resistance of the wire where the current is deployed? Given: Solution: V = 12 V I = 120 A R=?