Circuit Analysis I Notes

Basic Circuitry Concepts

• Students will understand and explore basic circuit components: wires, resistors, and voltage sources.
• They will practice building simple circuits.
• They will analyze circuits to find voltage, current, and resistance values.
• They will debug their circuits.
• Common circuit symbols are used.

Ohm’s Law

• Ohm's law states that the current ($I$) through a conductor between two points is directly proportional to the voltage ($V$) across the two points.
• Introducing the constant of proportionality, the resistance ($R$), the mathematical equation is: $I = \frac{V}{R}$.

Series and Parallel Resistors

In Series

• The total resistance of resistors connected in series is the sum of their resistance values.

In Parallel

• The total resistance of resistors connected in parallel is the reciprocal of the sum of the reciprocals of the individual resistors.

Measurement Devices: Voltmeter

• A voltmeter is an instrument used for measuring the electrical potential difference between two points in an electric circuit.
• A voltmeter must be connected in parallel to measure the voltage of a device.
• Objects in parallel experience the same potential difference.
• The voltmeter is a very high-impedance device; it would block the current in a circuit if connected in series.

Measurement Devices: Ammeter

• An ammeter (from Ampere Meter) is a measuring instrument used to measure the current in a circuit.
• Electric currents are measured in amperes (A), hence the name.
• An ammeter is connected in series with the circuit because the purpose of the ammeter is to measure the current through the circuit.
• Since the ammeter is a low-impedance device, connecting it in parallel with the circuit would cause a short circuit, damaging the ammeter and/or the circuit.

Circuit 1 Lab - Introduction to Circuit Analysis

• Prepared by: Engr. Sol Andrew Domingo

Objectives

• Learn how to use basic laboratory instruments: circuit boards, power supplies, and digital multimeters.
• Learn how to use digital multimeters for measuring voltage, current, and resistance.
• Be able to determine the resistance values based on resistor color codes.

Breadboard

• The breadboard has many strips of metal which run underneath the board.
• To use the breadboard, the legs of component are inserted into the holes.

Practice Example

• Implement a circuit with the following specifications:
  • $V = 5$ volts
  • $R1 = 620$ ohms
  • $R2 = 150$ ohms
  • $R3 = 220$ ohms

Practice Example

• Fill the table with measured and calculated values (Show your work)

CircuitLab Simulations

• Circuit diagram with the following components and measurements:
  • Voltage source $V1 = 5$ V
  • Resistor $R1 = 620 \Omega$
  • Resistor $R2 = 150 \Omega$
  • Resistor $R4 = 220 \Omega$
  • Ammeter $AM1 = 5.051$ mA
  • Voltmeter $VM1 = 3.131$ V
  • Voltmeter $VM3 = 0.7576$ V
  • Voltmeter $VM4 = 1.111$ V