CLASS COPY – DO NOT TAKE OR WRITE ON THIS SHEET!!
PHET -- Electrical and Magnetic Forces
Standards
9-11 PS1G
Electrical force is a force of nature independent of gravity that exists between charged objects.
Opposite charges attract while like charges repel.
• Predict whether two charged objects will attract or repel each other, and explain why.
9-11 PS1H
Electricity and magnetism are two aspects of a single electromagnetic force. Moving electric charges
produce magnetic forces, and moving magnets produce electric forces.
• Demonstrate and explain that an electric current flowing in a wire will create a magnetic field around the wire
(electromagnetic effect).
• Demonstrate and explain that moving a magnet near a wire will cause an electric current to flow in the wire
(the generator effect).
ANSWER ALL QUESTIONS IN YOUR COMPOSITION NOTEBOOK.
Part I: Magnetism
1.
2.
3.
4.
5.
a.
Go to http://phet.colorado.edu
Click on : “Play with Simulations” (blue box)
Click on : “Physics” on the left side
Click on : “Electricity, magnets, and circuits”
Click on: “Magnets and Electromagnets” and “Run Now”
Move the compass slowly along a semicircular path above the bar magnet until you’ve put it on
the opposite side of the bar magnet. Describe what happens to the compass needle.
b. What do you suppose the compass needles drawn all over the screen tells you?
c. Move the compass along a semicircular path below the bar magnet until you’ve put it on the
opposite side of the bar magnet. Describe what happens to the compass needle.
d. How many complete rotations does the compass needle make when the compass is moved once
around the bar magnet?
e. Click on the electromagnet tab on the top left of the screen. Place the compass on the left side of
the coil so that the compass center lies along the axis of the coil. (The y-component of the magnetic
field is zero along the axis of the coil.)
f. Move the compass along a semicircular path above the coil until you’ve put it on the opposite side
of the coil. Describe what happens to the compass needle.
g. Move the compass along a semicircular path below the coil until you’ve put it on the opposite side
of the coil. Describe what happens to the compass needle.
h. How many complete rotations does the compass needle make when the compass is moved once
around the coil?
i. Based on your observations, summarize the similarities between the bar magnet and the coil.
j. What happens to the current in the coil when you set the voltage of the battery to zero?
k. What happens to the magnetic field around the coil when you set the voltage of the battery to zero?
l. Play with the voltage slider and describe what happens to the current in the coil and the magnetic
field around the coil.
m. What is your guess as to the relationship between the current in the coil and the magnetic field?
Part II: Electric Circuits
1. Go back to the “Electricity, magnets, and circuits” simulators
2. Click on: “Circuit Construction Kit (DC Only)” and “Run Now”
Series Circuits: The current can only take one path
a. Build a simple series circuit that consists of 6 pieces of wire, 1 light
bulb, and 1 battery (voltage source). In order to complete the circuit,
the red circles at the end of each must overlap. Please note that the
light bulb also has TWO circles. Your circuit is complete and
working when the light comes on and the blue dots begin moving.
Draw a picture of your circuit.
b. What do you think that the moving blue dots represent?
Raise your hand and let your teacher check off your working series
circuit.
Click the reset button to begin working on a parallel circuit.
Parallel Circuits: The current can take more than one path.
a. Parallel circuits provide more than one path for electrons to move. Build a parallel circuit that
includes 10 wires, 2 light bulbs and 1 voltage source. The blue dots will be moving and both lights
will be on once the circuit is complete.
Sketch your circuit.
Raise your hand and let your teacher check off your working series circuit.