Professor Ahmadi， Xin Xu ECE 1020 DC Circuits Lab Professor Ahmadi， Xin Xu ECE 1020

Outline DC and AC circuit Omh’s Law Equivalent resistance in series and parallel cuicuits Exercises & Homework

Direct Current (DC) & Alternating Current (AC) DC: uni-directional movement of electric charges AC: the direction of the movement of electric charges reverses periodically

Ohm’s Law Quantifying the relationship between voltage and current V voltage, volt (V) I current, amp (A) R resistance ohm (Ω) I V R

An Example 3V = I x 1000 Ω I=3V / 1000 Ω = 3milliAmps Determine the current using Ohm’s Law 3V = I x 1000 Ω Solve for I: I=3V / 1000 Ω = 3milliAmps 3V R = 1K Ω I = ? Amps

Resisters in Series I R1 R2 R3 Apply Ohm’s Law on each resister V Just one path, currents are equal Equivalent resistance Voltage drops can be added up

Principles for Resisters in Series Current remains same in one circle Voltage can be added up Equivalent Resistance equal to sum of all resisters in series V R1 I R2 R3

Examples Online examples for resistances

Resisters in Parallel I R1 R2 R3 Apply Ohm’s Law on each resister V Voltages are same on each path Current is divided to 3 paths Equivalent resistance

Principles for Resisters in Parallel Voltages remain same in parallel paths Current can be added up I V R1 R2 R3

Examples Online examples for resistances

Combined I Find equivalent resistance for parallel resistances V R2 R3 R1 Solve the serial circuit I V Req R1

Examples Online examples for resistances

Exercises

Exercises – Ohm’s Law Given a circuit with a power source V = 9V,find the loop current if the resistance is 100 Ohm Find the loop current by hand, and then build the circuit using the online interactive simulator What is the current if the resistance is doubled What is the current if the resistances is reduced by 50% What is the current if the voltage is doubled? What is the current if the voltage is reduced by 50%

Exercises - series Given a circuit with a power source V = 12V,find the loop current if resistances are in series Find the loop current by hand, and then build the circuit using the online interactive simulator What is the loop current if all resistances are doubled What is the loop current if all resistances are reduced by 50%

Exercises - parallel Given a circuit with a power source V = 12V,find the loop current I if 2 resistances are connected in parallel Find the current I by hand, and then build the circuit using the online interactive simulator What is the current I if all resistances are doubled? What is the current I if all resistances are reduced by 50% I = ? V=12V R1 R2

Exercises - parallel Given a circuit with a power source V = 12V,find the loop current if 3 resistances are connected in parallel Find the current I by hand, and then build the circuit using the online interactive simulator What is the current I if all resistances are doubled What is the current I if all resistances are reduced by 50% I = ? V R1 R2 R3

Exercises – series/parallel Given a circuit with a power source V = 5V,find the loop current I if R1, R2 are connected in parallel, and then connected to R3 in series I = ? Find the current I by hand Build the circuit using the online interactive simulator to verify your results V R1 R2 R3

Exercises – series/parallel Given a circuit with a power source V = 5V,find the loop current if R1, R2, R3 are connected in parallel, and then connected to R4 in series I = ? Find the loop current I by hand Build the circuit using the online interactive simulator to verify your results V R1 R2 R3 R4

Exercises – series/parallel Find the loop current I by hand, and then build the circuit using the online interactive simulator I = ? V R4 R3 R1 R2

Homework Find the loop current I, and voltage and current for each resistor Build the circuit using the online interactive simulator to verify your results I = ? V R4 R3 R1 R2