Download Series and Parallel PhET

Series and Parallel PhET
A Quantitative Investigation
Introduction
Most electrical circuits, such as in a ipod or cell phone, contain many electrical
components connected together in multiple circuits. This investigation introduces two
ways to connect multiple devices in a circuit.
1. Open the following program file:
http://phet.colorado.edu/simulations/index.php
2. Select Circuit Construction Kit (DC only) - Run Now
Series Circuit
Directions:
1. Make a simple (one loop) circuit with one light-bulb. Measure the voltage across the lightbulb with the voltmeter and the current through it with a non-contact ammeter. Record your
answers below.
Voltage: ______________
Current: ________________
2. Make a simple (one loop) circuit with two light-bulbs daisy-chained in series. Measure the
voltage across i) both light-bulbs and ii) one of the light-bulbs, with the voltmeter, and the
current through both with a non-contact ammeter. Record your answers below.
i) Voltage across both bulbs: ________________
ii) Voltage across one of the bulbs in series: _______________
Current through the bulbs:
________________
Compare the voltage across one bulb when one its own to the voltage across both bulbs when
in series.
______________________________________________________________________________
Compare the voltage across one bulb when on its own to the voltage across one of the bulbs
when in series.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current flowing through two
bulbs in series.
______________________________________________________________________________
3. Make a simple (one loop) circuit with three light-bulbs daisy-chained in series. Measure the
voltage across i) all three light-bulbs and ii) one of the light-bulbs, with the voltmeter, and the
current through all three with a non-contact ammeter. Record your answers below.
i) Voltage across three bulbs: ________________
ii) Voltage across one of the bulbs in series: _______________
Current through the bulbs:
________________
Compare the voltage across one bulb when one its own to the voltage across all three bulbs
when in series.
______________________________________________________________________________
Compare the voltage across one bulb when on its own to the voltage across one of the bulbs
when in series.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current flowing through
three bulbs in series.
______________________________________________________________________________
If you add together the voltages across each bulb in series, what should they give? ___________
What conservation law does this obey? ______________________________________________
If each of the bulbs in series had different amounts of resistance would they share the battery
voltage equally? If not, which one would have a greater potential difference across it?
______________________________________________________________________________
______________________________________________________________________________
What happens to the current flowing out of the battery as more bulbs are added in series?
______________________________________________________________________
Does the overall resistance of the circuit increase or decrease as more resistors are added in
series? Explain!
It ___________________ because __________________________________________________
Parallel Circuit
Directions:
1. Make a two loop circuit with two light-bulbs in parallel branches. Measure i) the
voltage across one of the light-bulbs, with the voltmeter, and the current through it with a noncontact ammeter. ii) Measure the current coming out of the battery. Record your answers
below.
i) Voltage across one of the light bulbs: ________________
Current through one of the light bulbs: ________________
ii) Current coming out of the battery: _______________
Compare the voltage across one bulb when one its own to the voltage across a bulb when in
parallel with another.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current through one of the
bulbs when in parallel.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current flowing out of the
battery with two bulbs in parallel.
______________________________________________________________________________
2. Make a three loop circuit with three light-bulbs in parallel branches. Measure i) the
voltage across one of the light-bulbs, with the voltmeter, and the current through it with a noncontact ammeter. ii) Measure the current coming out of the battery. Record your answers
below.
i) Voltage across one of the light bulbs: ________________
Current through one of the light bulbs: ________________
ii) Current coming out of the battery: _______________
Compare the voltage across one bulb when one its own to the voltage across a bulb when in
parallel with another.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current through one of the
bulbs when in parallel.
______________________________________________________________________________
Compare the current through one bulb when on its own to the current flowing out of the
battery with two bulbs in parallel.
______________________________________________________________________________
If you add together the currents for each bulb in parallel, what should they give? ___________
What conservation law does this obey? ______________________________________________
If each of the bulbs in parallel had different amounts of resistance would they each have the same
current? If not, which one would have a greater current through it?
______________________________________________________________________________
______________________________________________________________________________
What happens to the current flowing out of the battery as more bulbs are added in parallel?
______________________________________________________________________
Does the overall resistance of the circuit increase or decrease as more resistors are added in
parallel? Explain!
It ___________________ because __________________________________________________
Current flowing into your home comes in through a mains wire and then is distributed throughout
the house via the circuit breaker box. Considering the way the house is wired, in parallel, what
role does the breaker box play, other than redistribute current? When answering this question
think about what happens when you plug another appliance into an outlet in your home! Also
think about what happens when too much current flows through a wire.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________