Ohm’s Law Foundations of Technology Ohm’s Law © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology Teacher Resource – Unit 4 Lesson 4

The BIG Idea Big Idea: Troubleshooting allows users to continue to use and maintain the proper operation of a system or product. © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology

Proposed by George Ohm, and is the relationship between Voltage, Current and Resistance. Voltage (V) = Current (I) X Resistance (R) Ohm’s Law © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology - + V R I V I R

Ohm’s Law is commonly expressed using the triangle found below where: Voltage (V) = Current (I) X Resistance (R) Current (I) = _Voltage (V)__ Resistance (R) Resistance (R) = _Voltage (V)_ Current (I) Ohm’s Law © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R

Voltage (V) is the electrical force that moves electrons through a conductor. Voltage is electrical pressure that pushes electrons. Voltage © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R

Current (I) is the quantity or flow rate of electrons moving past a point. Current flow is also known as amperage, or amps for short. Current © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R

Resistance (R) is the force that reduces or stops the flow of electrons and opposes voltage. Resistance © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R

Using Ohm’s Law determine the missing value for the following circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V R I Amp = ______Ώ

Using Ohm’s Law determine the missing value for the following circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V R I Amp = ______Ώ Resistance (R) = Voltage (V) Current (I) R = 4.5V 0.5Amp R = 9Ώ

Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V R I 10 Ώ 0.5 Amp _____ I = ______ Amp Using Ohm’s Law determine the missing values for the following circuit:

Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V R I 10 Ώ 0.5 Amp _____ I = ______ Amp I = 0.5 Amp - Current will be the same throughout the circuit Voltage (V) = Current (I) x Resistance (R) V = 0.5 Amp x 10 Ώ V = 5V

In a Series circuit, the current through two or more resistors is the same, and the circuit is connected in a series. The total resistance of the collection is the sum of individual resistances. Resistors in Series © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology

The total resistance of the collection is the sum of the individual resistances. The Equivalent Resistance of R1, R2 and R3 when connected in series is: R = R1 + R2 + R3 Resistors in Series © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology

Calculate the total resistance of the series circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ

Calculate the total resistance of the series circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ R = R1 + R2 + R3 R = 3 Ώ + 10 Ώ + 5 Ώ R = 18 Ώ

Calculate the total current of the series circuit: (current is the same throughout a series circuit) Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ R(total) = 18 Ώ

Calculate the total current of the series circuit: (current is the same throughout a series circuit) Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ R(total) = 18 Ώ Current (I) = Voltage (V) Resistance (R) I = 9V 18 Ώ I = 0.5 Amp

Using Ohm’s Law, calculate the voltage drop for each resistor in the series circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ 0.5 Amp

Using Ohm’s Law, calculate the voltage drop for each resistor in the series circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ V = I x R V(R1) = 0.5 Amp x 3 Ώ V(R1) = 1.5 V V(R2) = 0.5 Amp x 10 Ώ V(R2) = 5 V V(R3) = 0.5 Amp x 5 Ώ V(R3) = 2.5 V 0.5 Amp

Using Ohm’s Law, calculate the voltage drop for each resistor in the series circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 5 Ώ 10 Ώ 3 Ώ R1R2R3Total VVoltage AmpCurrent ΏResistance Remember Current (I) is the same across a series circuit. 0.5 Amp

In a Parallel circuit, the voltage through two or more resistors is the same, and the circuit is connected in parallel. The total resistance of the collection is divided among the three resistors. Resistors in Parallel © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology

The total resistance of the collection is divided among the three resistors. The Equivalent Resistance of R1, R2 and R3 when connected in parallel is: 1/R = 1/R1 + 1/R2 + 1/R3 Resistors in Parallel © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology

Calculate the total resistance of the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V 14.4 Amp 10 Ώ1 Ώ 2 Ώ I

Calculate the total resistance of the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R 1/R = 1/R1 + 1/R2 + 1/R3 1/R = 1/(10 Ώ) + 1/(2 Ώ) + 1/(1 Ώ) 1/R = 0.1 Ώ Ώ + 1 Ώ 1/R = 1.6 Ώ R = 1/(1.6 Ώ) R = Ώ - + V 14.4 Amp 10 Ώ1 Ώ 2 Ώ I

Calculate the total voltage of the parallel circuit: (voltage is the same across a parallel circuit) Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R R(total) = Ώ - + V 14.4 Amp 10 Ώ1 Ώ 2 Ώ I

Calculate the total voltage of the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R R(total) = Ώ Voltage (V) = Current (I) x Resistance (R) V = 14.4 Amp x Ώ V = 9V - + V 14.4 Amp 10 Ώ1 Ώ 2 Ώ Calculate the total voltage of the parallel circuit: (voltage is the same across a parallel circuit) I

Using Ohm’s Law, calculate the current across each resistor in the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 10 Ώ1 Ώ 2 Ώ 14.4 Amp

Using Ohm’s Law, calculate the current across each resistor in the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 10 Ώ1 Ώ 2 Ώ Current (I) = Voltage (V) Resistance (R) I(R1) = 9V 10 Ώ I(R1) = 0.9 Amp 14.4 Amp

Using Ohm’s Law, calculate the current across each resistor in the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - + V I 9 10 Ώ1 Ώ 2 Ώ Current (I) = Voltage (V) Resistance (R) I(R2) = 9V 2 Ώ I(R2) = 4.5 Amp 14.4 Amp

Using Ohm’s Law, calculate the current across each resistor in the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R - V Current (I) = Voltage (V) Resistance (R) I(R3) = 9V 1 Ώ I(R3) = 9 Amp 2 Ώ + I 9 10 Ώ1 Ώ 14.4 Amp

Using Ohm’s Law, calculate the current across each resistor in the parallel circuit: Practice Questions © 2013 International Technology and Engineering Educators Association, STEM  Center for Teaching and Learning™ Foundations of Technology V I R R1R2R3Total 9999 VVoltage AmpCurrent ΏResistance Remember Voltage (V) is the same across a parallel circuit. 2 Ώ + I 9 10 Ώ1 Ώ 14.4 Amp V