PASCO SF-8616_8617 COILS SET - Manual (Page 5)

scientific 3
012-03800A
Experiments
Nature of Magnetic Field from an Electro-
magnet
The coils from your PASCO Coils Set can be used in
conjunction with a d.c. power supply or a battery to produce
constant magnetic fields. Three possible experiments are
shown below.
Figure 6
In Figure 6, a d.c. power supply is connected to the coil. A
nearby magnetic compass is used to show the presence of a
magnetic field and its direction. By noting the direction of
the windings on the coil (See Figure 7), students can develop
the rule for current direction and the resulting magnetic field
direction. This experimental setup can be quantified, leading
to a determination of how much current, through how many
turns, is needed to produce a magnetic field equal to the
earth’s field. Specifics of the experimental design are left to
the teacher and student.
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Figure 7
In Figure 8a and 8b, a coil is shown with its magnetic axis
parallel to the table. A piece of cardboard is mounted so that
it can be inserted into the center of the coil and extend
beyond it on all sides. Iron filings are then sprinkled on the
cardboard around the end of the current carrying coil. The
magnetic field pattern can be quickly demonstrated.
Figure 8a
d.c. power
amperes
Figure 9
Figure 8b
ALTERNATIVE: Small magnetic compasses can be used to
probe around the coil to show its magnetic field.
Figure 9 shows a current carrying coil with a magnetic field
inside. The cross-piece from the U-shaped Core is shown
inserted in the coil, although the same experiment can be
performed without the core. The strength of the electromag-
net thus produced could be tested in a number of ways,
including the use of the PASCO SF-8606 Digital Gauss/
Tesla Meter. Note that the dramatic increase in magnetic
field strength with the addition of a core can be clearly
demonstrated.
Solenoid
If the cross piece from the U-shaped Core is inserted into a
coil, but not centered, it will be pulled into the coil when the
alternating current is turned on. This demonstrates the basic
action of a solenoid. In experiments with the 400-turn coil, a
voltage of 8-10 volts A.C. was successful in demonstrating
this principle. See Figure 10.
ac power
Iron Core
Figure 10
d.c. power
amperes
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compass