breadboard notes engineering

Measuring Resistance

• Instruments Used: Multimeter or voltmeter.

• Measuring Technique:

  • Insert the negative probe into the negative terminal and the positive probe into the positive terminal of the component being measured.

  • Measure resistance when the circuit is powered off.

  • This prevents damage to the multimeter and ensures accurate readings.

• Understanding Resistance:

  • When measuring resistance, it’s crucial to turn the multimeter to the ohm setting ().

  • The multimeter provides a small amount of power to measure the resistance.

  • Example: A 330 ohm resistor with a 5% tolerance will give a reading close to this value.

  • For instance, a reading of 323 ohms is acceptable within the tolerance range.

Measuring Current

• Technique:

  • Current should be measured in series; this requires breaking the circuit.

  • Example: Break the circuit by removing a switch, allowing measurement through a connected ammeter.

  • Current must flow through the ammeter and any subsequent components (e.g., an LED).

• Risks of Incorrect Measurement:

  • Measuring current in parallel (connecting directly across components) can burn out the multimeter's fuse.

  • This occurs because the ammeter is not designed to handle the full current unless isolated in series.

• Practical Steps:

  • When measuring current, connect the multimeter in series and observe the display.

  • Confirm the current measurement by observing values (e.g., 14.613 milliamps).

Measuring Voltage

• Technique:

  • Voltage is typically measured in parallel across components.

  • Example: Measure at the power source (battery) by connecting probes to the positive and negative terminals.

  • Expected Reading: 8.78 to 8.79 volts indicates a nearly full battery.

• Voltage Drop Across Components:

  • Measure voltage across components such as resistors to verify voltage drop.

  • For a functioning circuit, summing the voltages at each component (e.g., component one + component two) should equal the total supply voltage, following Kirchhoff's voltage law.

Kirchhoff's Voltage Law

• States that the total voltage around a closed loop in a circuit is equal to the sum of the voltage drops across all components in that loop.

• This concept is demonstrated through practical measurements using a multimeter.

Safety Tips

• Always ensure that the circuit is powered off before measuring resistance with an ohmmeter to prevent damage.

• Be aware of the risks involved in measuring current parallelly to avoid damaging the equipment or causing personal injury.

Experimentation and Assignment

• Students are required to document their experiments:

  • Capture measurements and observations using the multimeter.

  • Include pictures of circuits built on breadboards (series, parallel, and combination circuits).

  • Create presentations of their findings (e.g., Google Slides) encapsulating their experiment results.

• Practice troubleshooting circuits to foster problem-solving skills.