Download Are Electricity and Magnetism Related?

Buggé: Magnetism 2
Are Electricity and Magnetism Related?
Do any other objects besides magnets create magnetic fields? We found earlier that stationary
electrically charged objects do not, but maybe moving electric charges do…
2.1 Observe and find a pattern
In order to determine whether electric currents produce magnetic fields,
connect a battery and some wires. Make sure that one of the wires in the
circuit is aligned along the geographical north-south direction. Place a
compass below a north-south oriented wire with the battery disconnected
from the circuit; there is no current in the circuit. The needle points north.
https://www.youtube.com/watch?v=PB4tHSagdng
Direction of the current
Draw an arrow
representing the
orientationof the
compass when placed
below the wire.
N
Draw an arrow
representing the
orientation of the
compass when placed
above the wire.
A
Current flows in the
north-south direction in
the wire.
B
If you reverse the
battery poles, the
current now flows in a
south-north direction in
the wire above or below
the compass.
a. Use the thumb of your right hand to represent the direction of the current and your
four fingers of the same hand to represent the direction of the compass. Does the
orientation of your thumb and fingers describe a pattern between the direction of the
current and the orientation of the compass for all of the above experiments?
b. Come up with a reason why electric current (moving electrically charged particles) might
affect the behavior of magnets differntly than would stationary charged objects.
Buggé: Magnetism 2
2.2 Draw magnetic field lines for a coil when it is connected to a battery. How do the B-field lines
compare to those for a bar magnet?
2.3 Draw magnetic field lines for a solenoid when it is connected to a battery. How do the B-field
lines compare to those for a bar magnet?
2.4 Draw the B-field lines for each section of the following circuits:
2.5 Use the right hand rule for the B-field and the superposition principle to predict the direction of
the magnetic field exactly in the middle between two straight wires oriented horizontally in the
plane of the page. The current through the top wire is toward the right and the current through the
bottom wire is toward the left.
2.6 What is the direction of the B-field at a point that is exactly in the middle between two straight
wires with currents in the same direction?
2.7 Imagine that a wire passes up through the page you are reading. Iron filings are sprinkled on the
page. We can think of the iron filings as small compasses. Draw a picture showing the filings
when no current is moving in the wire. Then draw a picture of the arrangement of the filings
when there is a significant current in the wire.
a. Is your picture consistent with the results of the experiment above? Explain your answer.
b. Draw a sketch that you think represents the orientation of magnetic field vectors produced by
the electric current in the wire at five different points. (Hint: Choose the direction of the
current out of the page.)
2.8 Current flows in each of the wires shown in the illustration. Determine the direction of the
magnetic field created by the current at the points indicated and draw it with an arrow, a dot (out
of the page), or a cross (into the page). The objects indicated in the illustration are sources of
magnetic field.
(a)
(b)
(c)
A.
A
.
B
.
C
.
A
.
B
.
C
.
D
.
B .
C.
E.
I
I
E .
I
. D