Series Circuits Lab
How do you use Ohm's Law in a Series Circuit?
Purpose:
You will determine how to calculate total resistance in a series circuit.
You will build a circuit with a dimmer switch.
Materials:
Batteries, resistors, meter, wires, bulb and bulb holder, potentiometer
FOR ALL MEASUREMENTS, MAKE SURE METER IS SET UP CORRECTLY!
You will determine how to calculate total resistance in a series circuit.
You will build a circuit with a dimmer switch.
Materials:
Batteries, resistors, meter, wires, bulb and bulb holder, potentiometer
FOR ALL MEASUREMENTS, MAKE SURE METER IS SET UP CORRECTLY!
Copy these tables into your notebook before beginning.
Procedure:
- Measure voltage of the battery. Record in table 1. Measure the resistance and the color band of the R1 resistor. Record in table 1. Measure the resistance and the color band of the R2 resistor. Record in table 1. Measure the resistance and the color band of the R3 resistor. Record in table 1.
- Build a circuit using ONLY the R1 resistor. Measure the current through the circuit. Remember you must OPEN the circuit in order to measure current. Record the value in table 2.
- Add the R2 resistor to your circuit. (Your circuit should now have two resistors.)
- Measure the current though the circuit. Record the value in table 2.
- Add the R3 resistor to your circuit.
- Measure the current though the circuit. Record the value in table 2.
- Using Ohm's Law calculate the total resistance in each circuit, using the battery voltage and the current for each circuit. Record this value in table 2.
- Build a new circuit with a bulb, potentiometer, and battery.
- Using the dimmer switch, turn the bulb until the light is very dim.
- Record approximate brightness in table 3. (Bright, very bright, very dim, dim, etc.)
- Measure voltage across the bulb. Remember "across" means from one side to the other. Record in table 3.
- Measure current through the circuit. Record in table 3.
- Make the bulb a little brighter and repeat steps 8-12. Continue for a total of FIVE settings of the potentiometer.
- Use Ohm's Law to calculate the total resistance for each setting of the potentiometer. Record these measurements in table 3.
Analysis: Complete in lab book, then upload a photo of your answers.
- Graph bulb resistance (y-axis) vs. current (x-axis) for each potentiometer setting. Label your axes and title your graph.
- What happens to bulb resistance when current is higher?
- How could you use series circuits when building your model house next week?
- At higher temperatures, the tungsten atoms in the light bulb filament move around more. Propose an explanation for why resistance of tungsten increases with temperature.