lab (Demonstration of circuit equipment using an LED Construct, analyze, and validate two simple circuits)

LAB # 4 Demonstration of circuit equipment using an LED

Construct, analyze, and validate two simple circuits

Circuit Setup Demonstration • The circuit should be wired as shown.

• Notice the LED has a cathode (-) and anode (+) connection. If wired backwards the LED will not turn on.

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Breadboard Layout • A bread or “prototyping” board is how the all of the circuit

elements will be wired together. • Each row of five holes are a single connection point. This

allows you to create nodes consisting of multiple branches.

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Example with LED in circuit 4

Multimeter Basics • A multimeter is an important piece of equipment for

electrical engineers. • Multimeters measure a variety of parameters, such as

voltage, current, resistance, capacitance, and much more. • Multimeters come in analog and digital forms.

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Measuring Current • Set the multimeter to DCA (direct current amps) 20m. • Remember current is a “THROUGH” variable and the

meter must be placed in series in the circuit.

• DO NOT connect the multimeter in parallel with any element while in DCA mode. Result will be a damaged multimeter.

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Measuring Voltage • Set the multimeter to DCV (DC volts) 20. • Remember voltage is an “ACROSS” variable. You must

connect the multimeter in parallel with the element in which you want to take the voltage.

• Connect red wire to positive terminal and black to negative.

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Measuring Resistance • Set the multimeter to Ω 2000. • Disconnect resistor from circuit. • Connect leads in parallel across the resistor.

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Lab # 4 Overview • Teams of 3 will build two simple circuits. Each circuit will

have a power supply and a resistor (either a 1 kΩ or 1.5 kΩ resistor). (No LED should be included in these circuits.)

• Using a multimeter, measurements of current, voltage, and resistance will be taken.

• Teams will calculate resistance and power from the measurements taken above for each circuit.

• Record your measurements and calculations on the provided data sheet.

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Lab 4 Procedure & Deliverables Do not use a LED when testing this circuit.

1. Build your circuit on the breadboard and configure your circuit to include your multimeter. Record the total current I moving through your circuit. (see slide 6 for guide)

2. Measure the voltage across the resistor in your circuit. (see slide 7 for guide)

3. Calculate resistance from the measured voltage and current values.

4. Measure the resistance for the resistor in the circuit (see slide 8 for guide). Compare the measured resistance to the calculated value of resistance of the resistor.

5. Calculate the power absorbed by the resistor.

6. Repeat steps 1-5 for the second resistor.

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Notes on Lab 4 Deliverables: • Turn in “Team Data Sheet” at the end of class.

• Make sure each team member’s name is included on the data sheet.

• Make sure that each team member has a chance to build the circuit and take measurements.

• Record at least 3 values for each measurement required in your circuit.

• Make sure all supplies are returned to the instructor as you received it. Both multi-meters must be turned “off” and both leads are neatly “rubber banded” to the meter.

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