Download Name Electricity Web-quest Ohm`s Law http://phet.colorado.edu/new

NAME ______________________________________DATE ____________________HR_________
ELECTRICITY WEB-QUEST
Ohm’s Law
http://phet.colorado.edu/new/simulations/index.php?cat=Electricity_Magnets_and_
Circuits, Select the Ohm’s Law simulation.
1. What do each of the letters in the formula represent? What are the units of
each?
Move the buttons up and down on the right
2. What happens to the formula as you move the voltage button? ...The resistor button?
3. What happens to the diagram as you move the voltage button? ...The resistor button?
4. Explain the relationships between the variables in this formula. (V and R, I and R)
5. Draw the corresponding schematic diagram for the circuit.
Circuit Construction Kit (DC only)
http://phet.colorado.edu/new/simulations/index.php?cat=Electricity_Magnets_and_
Circuits, select the Circuit Construction Kit (DC only) simulation.
Before you begin, briefly define the following terms:
 Series Circuit
 Parallel Circuit
 Resistor
 Current
Instructions The way to build a circuit is to click on the item you need & the menu
and drag it out into the main field
 The spheres moving in the wire represent the electrons moving in a
circuit.
 You can the change resistor values by right clicking on the resistor.
Main
field
Menu
Background – Everyday we use devices that have electric circuits in them; they perform different tasks for us. It
is the design of the circuit that enables them to perform these different tasks. We will look at the two basic
designs of circuits and learn a little about how they are different.
Find a way to make a single light bulb light up with as FEW parts hooked up as possible.
1. Sketch your circuit below:
2. Use the voltmeter to determine the voltage from one side of the battery to another and from one side of the
bulb to the other.
Make a gap in your circuit. Go to the grab bag and play with the different objects. Find out which objects allow
electricity to flow and fill in the data table:
1. What do the conductors have in common?
2. What do the insulators have in common?
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For the next few activities, you need to light up 2 bulbs at the same time, using just one battery.
Hook up your bulbs in a way that if you break the connection at one bulb, ALL bulbs go out.
3. Sketch your new circuit:
4. Why did the rest of the bulbs go out if you break the connection at one bulb?
5. Use the voltmeter to find the voltage across each light bulb and the voltage across the battery. How do
these values compare?
Second circuit: find a way to hook up your bulbs in a way that if you break the connection at one bulb, ONLY
that bulb goes out.
6. Sketch this circuit:
7. Why do the rest of the bulbs stay lit if you break the connection at one bulb?
8. Use the voltmeter to find the voltage across each light bulb and the voltage across the battery. How do
these values compare?
Experiment with the simulator, see what you can make it do!!!
9. What did you do to make light bulbs glow brighter?
10. What did you do to make light bulbs glow dimmer?
11. How can you cause a fire? (In the simulator… NOT in the real world!)
7. Apply what you learned. Write a paragraph (at least 3 good sentences!) about how series and parallel
circuits are similar and how they are different, by looking at your work in steps 4 & 6. Include the following
 Possible pathways the electric current can move in the series and parallel circuits,
 How different resistance values for the individual resistors affects the current in the series and
parallel circuits.
JOHN TRAVOLTAGE
Everyone is familiar with the somewhat painful implications of electrostatics. After
shuffling across the floor, we accumulate a charge. Often, the first we know of this
development is when the charge rapidly leaves our body through contact with
another object. Charging by contact (and the ultimate discharge) is portrayed in the
following simulation starring John Travolta.
http://phet.colorado.edu/new/simulations/index.php?cat=Electricity_Magnets_and_
Circuits, select Travoltage.
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Have fun zapping JT. Then answer the following questions:
1. Describe the charge distribution on JT prior to discharge. (How much charge is there? Where is it
located?)
2. Compare charging and discharging. What is the biggest difference?
3. Based on this observation, why discharge is often accompanied by pain, but charging is barely even
noticed?
4. Observe discharges at several arm positions. At what positions does discharge occur nearly instantly and
at what positions does discharge not occur?
Balloons and Static Electricity
Another common case of electrostatics is static cling. An unruly balloon is used
in the following simulation.
As you are most likely aware, charge can be described as either positive or
negative. When + or – charges are present in roughly equal concentrations,
the object is said to be neutrally charged. Large numbers of the negative
particles (or electrons) can be transferred in certain circumstances from one
neutral surface to another. This generates an object with an excess of + charges
and an object with an excess of – charges. The following simulation illustrates the movement of both + and –
charges and the resulting attractive and repulsive forces.
http://phet.colorado.edu/new/simulations/index.php?cat=Electricity_Magnets_and_Circuits, select the Balloon
simulation.
1. Before playing with the balloon, how would you describe the charge and its distribution on the sweater,
the balloon, and the wall? (Use words like evenly or unevenly distributed)
2. Describe what happens when the balloon is rubbed against the wall.
3. Predict what will happen when the balloon is returned to the center of the room. Confirm your
prediction.
4. What changes occur when the balloon is rubbed against the sweater? (Consider changes to both the
balloon and the sweater.)
5. Predict what will happen when the balloon is returned to the exact center of the room. Confirm your
prediction. Why does this happen (form a hypothesis)?
6. Use your hypothesis to predict what will happen when the balloon is placed very near, but not touching
the wall.
7. Run this experiment and sketch the result. Did you see what you expected?
This shifting of charges on the neutral wall is called charging by induction. Take a moment to experiment with a
single balloon before proceeding to the next step.
Now reset the simulation and add a second balloon. Rub each balloon against the sweater in order to acquire a
small charge. Return both balloons to the center of the room.
8. Predict what will happen when you try to put the balloons in contact with each other. Why?
9. Based on your observations of the Travoltage and Balloon simulations, attempt to explain why you
sometimes see flashes of light when removing a fleece jacket in a dark room.
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