General Physics 2 General Physics 2 Prepared by Ella Mae Kate Goopio Nairah M. Macarimbang Geneel Jan Manzanares 1 General Physics 2 “Picture Prompt” 1 General Physics 2 GEFORIRARETR 1 General Physics 2 REFRIGERATOR 1 General Physics 2 ICERELRT ANF 1 General Physics 2 ELECTRIC FAN 1 General Physics 2 NEOLETISIV 1 General Physics 2 TELEVISION 1 General Physics 2 ERCI OKOECR 1 General Physics 2 RICE COOKER 1 General Physics 2 Eifl utohiwt ycelertiit. 7 General Physics 2 Life without electricity. https://alexyvergara.files.wordpress.com/2014/07/typhoon-glenda-brownout.jpg 8 General Physics 2 Electricity The science behind electricity 9 General Physics 2 Module 4: Electric Current, Resistance and Ohm’s Law • Current, resistivity, and resistance • Ohm’s law • Energy and power in electric circuits • Electrical safety 5 General Physics 2 Electric Current, Resistivity and Resistance Electric Current, Resistivity and Resistance 10 General Physics 2 Learning Objectives: 1. Discuss the electric current, resistivity and resistance 2. Distinguish conventional current and electron flow 3. Calculate the electric current and resistivity 5 General Physics 2 Electric Current, Resistivity and Resistance SIMPLE CIRCUIT 10 General Physics 2 Electric Current, Resistivity and Resistance SIMPLE CIRCUIT 10 Electric Current, Resistivity and Resistance General Physics 2 The SI unit for current 10 General Physics 2 Electric Current, Resistivity and Resistance Electric Current is the flow of electrons through a path. Electron – the moving charges. 11 Electric Current, Resistivity and Resistance General Physics 2 Electric Current It is represented by capital (πΌ) and mathematically expressed as; Physical Quantity Current Charge 1 C 1π΄ = [π ] Time Symbol Unit I [A] Q t (Ampere) [c] (Coulomb) [s] (second) ππππππ‘πππ = −1.602 π₯10 Current is directly proportional to charges, and it is inversely proportional to time in seconds. −19 c Electric Current, Resistivity and Resistance General Physics 2 Calculating the current A charge of 150 coulombs flows through a conductor in a time period of 30ΰ΄€ seconds. Calculate the electric current. G: U: E: S: 13 Electric Current, Resistivity and Resistance General Physics 2 Calculating the current A charge of 150 coulombs flows through a conductor in a time period of 30 seconds. Calculate the electric current. G: U: π = 150πΆ π = 30π πΌ =? E: S: I=? I=? = 5.0 A 14 Electric Current, Resistivity and Resistance General Physics 2 Current Flow + to - - to + 16 General Physics 2 Electric Current, Resistivity and Resistance Conventional Flow vs. Electron Flow 16 General Physics 2 Electric Current, Resistivity and Resistance Conventional Flow vs. Electron Flow Conventional Current Flow: • From the (+) terminal of a voltage source to the (-) terminal. • It represent the movement of positive charge carriers (even though, in reality, electrons are negatively charged and move in the opposite direction). Electron Current Flow: • From the (-) terminal of a voltage source to the (+) terminal. • It represent the actual movement of electrons. 15 Electric Current, Resistivity and Resistance General Physics 2 SIMPLE CIRCUIT Electron Current Flow 10 Electric Current, Resistivity and Resistance General Physics 2 Resistance -a measure of how difficult current to pass through It is mathematically expressed as; wire. Physical Quantity O Resistance Symbol Unit R [Ω] (Ohm) [Ω·m] Resistivity (ohm meter) Length L [m] (meter) 2 A= π · D² / 4 Area A [m ] (meter squared) 17 General Physics 2 Electric Current, Resistivity and Resistance Resistivity values for various conducting materials are typically listed below: Electric Current, Resistivity and Resistance General Physics 2 Calculating the Resistance What is the resistance of an aluminum wire that is 10 π long and −8 has a diameter of 3.0 ππ if the resistivity is 2.65π₯10 Ω β π? G: U: E: S: 19 Electric Current, Resistivity and Resistance General Physics 2 Calculating the Resistance What is the resistance of an aluminum wire that is 10π long and −8 has a diameter of 3.0 ππ if the resistivity is 2.65 × 10 Ω β π? G: U: E: S: S: π =? R=? π = 3.8 π₯ 10−2 Ω General Physics 2 Electric Current, Resistivity and Resistance 22 General Physics 2 Electric Current, Resistivity and Resistance 21 General Physics 2 Electric Current, Resistivity and Resistance Practice Problem 23 Electric Current, Resistivity and Resistance General Physics 2 Problem 1 A current of π. π π¨ flows through a resistor for ππ πππ . How many electrons flow during the time given? G: U: E: S: 24 Electric Current, Resistivity and Resistance General Physics 2 Problem 2 A copper wire has a length of π. π π and a cross-sectional area π of π π ππ − π π . Calculate the resistance of the copper wire. G: U: E: S: 24 General Physics 2 Electric Current, Resistivity and Resistance Seatwork 26 Electric Current, Resistivity and Resistance General Physics 2 A. Solve and complete the given table. Show your solution. No. Charge 1. 60 π 2. 150 π 4. 0.15 π Time 3π 2π΄ 3. 5. Current 2 πππ 10 π΄ 3π 0.50 π΄ 25 π 27 General Physics 2 Electric Current, Resistivity and Resistance B. Solve the following problems relative to the resistance. 1. Calculate the resistivity of a material that has a length of −π π ππ π and a cross-sectional area of π × ππ π and a resistance (R) of π π. 28 General Physics 2 Module 4: Electric Current, Resistance and Ohm’s Law • Current, resistivity, and resistance • Ohm’s law • Energy and power in electric circuits • Electrical safety 5 Ohms Law General Physics 2 Ohm’s Law 34 Ohms Law General Physics 2 “Ohms Law HINT: Voltage, Current, Resistance 35 Ohms Law General Physics 2 “Ohms Law HINT: Voltage, Current, Resistance 36 General Physics 2 Ohms Law 37 Ohms Law General Physics 2 Ohm’s Law - It explains relationship between voltage, current, and resistance. This law was developed by the German physicist named Georg Simon Ohm. V=I.R Physical Quantity Symbol Unit Voltage V [v] Current I [A] Resistance R [β¦] 38 Ohms Law General Physics 2 V=I.R Volatge (v) = Current(I)X Resistance(R) Current(I) = Voltage (v)/ Resistance(R) Resistance(R) = Voltage(v)/Current(I) 40 Ohms Law General Physics 2 Ohmic vs. Non-Ohmic Ohmic materials • Follow Ohm's Law (V=I⋅R). • linear relationship between voltage and current. Most metals, aluminum. Non-Ohmic materials • Do not strictly follow Ohm's Law (V=I⋅R). • non-linear relationship between voltage and current. copper, Semiconductors, diodes, thermistors. 44 General Physics 2 Ohms Law Ohmic vs. Non-Ohmic 44 General Physics 2 Ohms Law 46 General Physics 2 Ohms Law 47 General Physics 2 Ohms Law Practice Problem 23 Ohms Law General Physics 2 Problem 1 A circuit contains a resistor with a resistance of 50 ohms. If a voltage of 20 volts is applied across the resistor, calculate the current flowing through the circuit. G: U: E: S: 48 Ohms Law General Physics 2 Problem 1 A circuit contains a resistor with a resistance of 50 ohms. If a voltage of 20 volts is applied across the resistor, calculate the current flowing through the circuit. G: R = 50ohms V = 20v U: E: I=? V I=I.R R S: 49 General Physics 2 Module 4: Electric Current, Resistance and Ohm’s Law • Current, resistivity, and resistance • Ohm’s law • Energy and power in electric circuits • Electrical safety 50 General Physics 2 Let’s review! FIND the LIE 31 General Physics 2 We discussed…. • Ohm’s Law 33 General Physics 2 DECODE ME 31 General Physics 2 Energy and power in electric circuits :/:=358083&):?85=: the driving force that pushes electric charges around a circuit. 53 General Physics 2 Energy and power in electric circuits ELECTROMOTIVE FORCE the driving force that pushes electric charges around a circuit. 53 General Physics 2 Energy and power in electric circuits :/:=35&= =&=;&34 provide a pathway for the flow of electric current, enabling the operation of various electrical devices and components. 53 General Physics 2 Energy and power in electric circuits ELECTRIC CIRCUITS provide a pathway for the flow of electric current, enabling the operation of various electrical devices and components. 53 Energy and power in electric circuits General Physics 2 7 8< : 5 A rate at which work is done or energy is transferred 53 Energy and power in electric circuits General Physics 2 POWER A rate at which work is done or energy is transferred 53 General Physics 2 Energy and power in electric circuits Hints: Energy ,Power ,Electromotive force ,Circuits 53 General Physics 2 Energy and power in electric circuits Electromotive Force power circuits Hints: energy Energy ,Power ,Electromotive force ,Circuits 53 General Physics 2 Energy and power in electric circuits 51 General Physics 2 Energy and power in electric circuits 53 General Physics 2 ELECTROMOTIVE FORCE Energy and power in electric circuits SYMBOL OF ELECTOMOTIVE FORCE EMF is denoted by (E) and it is also denoted by the symbol ε. is the energy transfer to an electric circuit per unit of electric charge. It represents the work done by a source in driving a unit charge around a complete circuit. UNIT OF ELECTROMOTIVE FORCE EMF = energy gained (W) / unit charge (Q) = Joules / Coulombs = Volt 52 Energy and power in electric circuits General Physics 2 FORMULA FOR ELECTROMOTIVE FORCE EMF (ε) = voltage of the cell + (current across the circuit x internal resistance of the cell) πΊ = π½ + π°π Where: V = the voltage of the cell I = the current across the circuit r = the internal resistance of the cell ε = the electromotive force 52 General Physics 2 Energy and power in electric circuits SOURCES OF ELECTROMOTIVE FORCE (EMF) BATTERY 53 General Physics 2 Energy and power in electric circuits SOURCES OF ELECTROMOTIVE FORCE (EMF) KIBAWE 10.5MW SOLAR POWERED POWER PLANT 53 General Physics 2 Energy and power in electric circuits SOURCES OF ELECTROMOTIVE FORCE (EMF) PULANGI IV HYDROELECTRIC PLANT 53 Energy and power in electric circuits General Physics 2 COMPLETE CIRCUIT -is a conducting loop that provides a continuous current carrying path. -carrying a steady current must contain a source of electromotive force (emf). 53 General Physics 2 The potential difference is equal to the electromotive force: Vab = ε Energy and power in electric circuits Vab = ε = Ir ( source with internal resistance) An ideal source of EMF maintains a constant potential difference, independent of current through the device, but every real source of EMF has some internal resistance r. The terminal voltage Vab then depends on current. 53 General Physics 2 Energy and power in electric circuits Take note that the current is equal to the source emf divided by the total circuit resistance (from the resistor and the real source). 53 General Physics 2 Energy and power in electric circuits ELECTROMOTIVE FORCE VS. POTENTIAL DIFFERENCE 53 General Physics 2 Energy and power in electric circuits 53 General Physics 2 Energy and power in electric circuits CIRCUITS IN DIAGRAMS 53 General Physics 2 Module 4: Electric Current, Resistance and Ohm’s Law • Current, resistivity, and resistance • Ohm’s law • Energy and power in electric circuits • Electrical safety 50 General Physics 2 Energy and power in electric circuits Energy and Power in electric circuits 51 General Physics 2 Energy and power in electric circuits Electric Energy • The amount of the work done to force the current to flow through an electric circuit. • It is measured in Joule [J]. • It associated with other form of energy. Electric Power • The rate at which electric energy is used, transferred, dissipated or consumed instantaneously. • It is measured in Joule/sec or Watt 53 General Physics 2 Energy and power in electric circuits ENERGY AND POWER IN A CIRCUITS POWER ENERGY Three expressions for electric power: Three expressions for electric Energy: Where; P = Power in watts [W] I = Current in Amperes [A] V = Voltage in Volts [v] R = Resistance [πΊ] Where; P = Power in watts [W] t = Time in seconds [s] I = Current in Amperes [A] V = Voltage in Volts [v] R = Resistance [πΊ] General Physics 2 Ohms Law Calculating Power and Energy A television operates with a power consumption. The television is used for a certain number of hours each day. A. If the television has a current of 2.0 A and operates at a voltage of 120 V, calculate the power consumption. B. The television is used for 6.0 βππ’ππ each day. Calculate the total energy consumed by the television. 48 Electric Current, Resistivity and Resistance General Physics 2 Calculating Power and Energy A television operates with a power consumption. The television is used for a certain number of hours each day. A. If the television has a current of 2.0 A and operates at a voltage of 120 V, calculate the power consumption. B. The television is used for 6.0 βππ’ππ each day. Calculate the total energy consumed by the television. G: I= π. π π¨ π½ = ππππ π» = π. πππ E: U: A) P=? B) E = ? A) b) S: π΄. ) π = (2.0 π΄)(120π) = πππ πΎ π΅. ) πΈ = (240π)(360π ) = 86,400 = π. π × πππ π± 14 Energy and power in electric circuits General Physics 2 Power Influenced by the EMF REAL RESISTOR πΊ= π° πΉ+π π= EMF r= internal resistor R= Resistor IDEAL RESISTOR 51 Energy and power in electric circuits General Physics 2 EMF Equation πΊ=π° πΉ+π π = πΌπ + πΌπ π = πππ + πΌπ Power Influence by the EMF πππ = π − πΌπ πΌπππ = I(π − πΌπ) 2 π = πΌπ - πΌ π Power Input Power output General Physics 2 Energy and power in electric circuits Power input - electrical power supplied to a circuit. It represents the rate at which energy is provided to the circuit from an internal source, such as a power supply. 53 General Physics 2 Energy and power in electric circuits Power output- the electrical power delivered by the circuit. It represents the rate at which the circuit delivers energy to external devices, such as motors, lights, or any other electrical loads. 53 General Physics 2 Energy and power in electric circuits ENERGY AND POWER IN A CIRCUITS Power Energy Power input Power output Ohms Law General Physics 2 Let’s Play “Keep or Give” 23 General Physics 2 Consider that you have a circuit with a potential difference of π. π π½, with a current of π. π π¨. The internal resistance of the battery at π. π ππππ. Use EMF Formula. Given : Solution : 23 General Physics 2 Consider that you have a circuit with a potential difference of 3.2 V, with a current of 0.6 A. The internal resistance of the battery at 0.5 ohms. Use EMF Formula. Given: π = 3.2 π πΌ = 0.6 π΄ π = 0.5 πβπ Solution: By using the formula: ε = V + Ir π = 3.2 + 0.6 π 0.5 = 3.2 π + 0.3 π = 3.5 π the EMF of the circuit is 3.5 V. 23 General Physics 2 Electric Current, Resistivity and Resistance Seatwork 26 General Physics 2 Energy and Power in a Circuits A D cell of emf 1.5 V and internal resistance of 0.3 Ω is connected to a flashlight which resistance is 3.0 Ω Find the current in the circuit and the terminal voltage of the cell. 23 General Physics 2 Energy and Power in a Circuits A D cell of emf 1.5 V and internal resistance of 0.3 Ω is connected to a flashlight which resistance is 3.0 Ω Find the current in the circuit and the terminal voltage of the cell. 23 General Physics 2 Energy and Power in a Circuits What is the rate of energy conversion and dissipation in the battery, net power output if the battery has an emf of 12 π, a current of 2 π΄, resistance of 4 Ω and internal resistance of 2 Ω? 23 General Physics 2 Energy and Power in a Circuits What is the rate of energy conversion and dissipation in the battery, net power output if the battery has an emf of 12 π, a current of 2 π΄, resistance of 4 Ω and internal resistance of 2 Ω? 23 General Physics 2 Module 4: Electric Current, Resistance and Ohm’s Law • Current, resistivity, and resistance • Ohm’s law • Energy and power in electric circuits • Electrical safety 50 General Physics 2 Electric Current, Resistivity and Resistance Electrical safety 10 Energy and power in electric circuits General Physics 2 ELECTRICAL SAFETY practices and precautions taken to prevent accidents and injuries caused by electricity. 52 General Physics 2 Electric Current, Resistivity and Resistance SAFETY SIGNS for ELECTRICALS 10 Energy and power in electric circuits General Physics 2 FUSE an electrical safety device that operates to provide overcurrent protection of an electrical circuit. 52 General Physics 2 Energy and power in electric circuits FUSE 52 Energy and power in electric circuits General Physics 2 CIRCUIT BREAKER an electrical safety device designed to protect an electrical circuit from damage caused by overcurrent. 52 General Physics 2 Energy and power in electric circuits Mag-ina, patay nang makuryente nang mahulog sa tubig ang extension ng saksakan habang naglalaba. https://www.gmanetwork.com/news/balitambayan/balita/787382/mag-ina-patay-nang-makuryente-nang-mahulog-sa-tubig-ang-extension-ng-saksakanhabang-naglalaba/story/?fbclid=IwAR2Nw8Nh-IQKjHu-eYG6VUIC1lwh2Txzwec4NG9dET6kW8uR0hZK8XJCiCc 52 General Physics 2 Energy and power in electric circuits https://www.facebook.com/photo.php?fbid=285466434564171& id=100093024494930&set=a.111191918658291&locale=tr_TR 52 General Physics 2 Energy and power in electric circuits EFFECT OF CURRENT IN OUR BODY 52 General Physics 2 Energy and power in electric circuits ELECTRICAL SAFETY TIPS 52 General Physics 2 Energy and power in electric circuits ELECTRICAL SAFETY TIPS 52 General Physics 2 SUMMATIVE TEST 23
