Science 9Collingwood School

A Series circuit (of Lights) versus Parallel circuit (Lights)

Name:

/ 20Date:

Block:

Series Circuit Diagram:Parallel Circuit Diagram:

Method:

  1. Open 2 separate windows using the Phet simulation website
  2. Begin with a series circuit, construct a circuit with a 20 volt battery,pathway, two bulbs (bulb# 1 – 30 ohms, bulb #2 – 10 ohms), and an ammeter beside each bulb.
  3. measure the value of the current beside bulb# 1, then bulb # 2 by completing Table 1.
  4. measure the voltage across each resistor (bulb # 1 and # 2) by completing Table 1.
  5. Draw a ‘labeled’ circuit diagram of a series circuit above
  6. Construct a parallel circuit in a separate window, with a 20 volt battery, pathway, two bulbs (bulb# 1 – 30 ohms, bulb #2 – 10 ohms), and an ammeter beside each bulb.
  7. measure the value of the current beside bulb# 1, then bulb # 2 by completing Table 2, the same for voltage.
  8. Finally, calculate the resistance across each resistor using ohms law.
  9. e.g. using your values in Table 1 (series circuit), calculate the resistance (R=V/I)
  10. Complete a calculation for total resistance for both tables.

Table 1: ______

Series Circuit(20 Volts)
Current (mA)
measured / Voltage (V)
measured / Resistance (Ω)
calculated
Ammeter 1
between battery and bulb # 1 / Bulb 1
30 Ohms
Ammeter 2
between battery and bulb # 2 / Bulb 2
10 Ohms
TOTAL Resistance
Rt = R1 + R2 / Rt =

Table 2: ______

Parallel Circuit (20 Volts)
Current (mA)
measured / Voltage (V)
measured / Resistance (Ω)
calculated
Ammeter 1
between battery and bulb # 1 / Bulb 1
30 Ohms
Ammeter 2
between battery and bulb # 2 / Bulb 2
10 Ohms
TOTAL Resistance
/ Rt =

SummaryQuestions:

  1. Looking at a series circuit, compare the value of the current in ammeter 1 to the current in ammeter 2. What do you notice?

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  1. Looking at a series circuit, compare the value of the voltage across bulb 1 to the value of voltage across bulb 2. What do you notice?

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  1. Looking at the parallel circuit, compare the value of the current in ammeter 1 to the current in ammeter 2. What do you notice?

______

  1. Looking at the parallel circuit, compare the value of the voltage across bulb 1 to the value of voltage across bulb 2. What do you notice?

______

  1. Add another resistor to the series circuit, a 10 ohm light bulb.
  2. Would the total resistance increase or decrease? ______
  3. What is the voltage drop over the first bulb? ______
  4. What is the voltage drop over the first and second bulb? ______
  5. What connection can you determine from these results (hint – in terms of total voltage)

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  1. Add another resistor to the parallel circuit, a 10 Ohm Light Bulb.
  2. Would the total resistance increase or decrease? ______
  3. By adding another resistor, did the total current increase of decrease? ______
  4. What connection can you determine from these results (hint – in terms of total resistance and current)______

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