3B Scientific Advanced Electricity and Magnetism Kit - Manual (Page 3)

Electricity/E506 Work sheet SEK
2
Sub-experiment 2:
Set-up and procedure
1) Connect the coil with a tap at 200 windings in
series with the first one and assemble a circuit
as in Fig. 2.
2) Set the power supply to operate with direct
current (DC) and turn the knob to 6 V.
3) Set the voltmeter to 1000 mA=.
4) Insert the yoke into the coil with 200 windings.
5) Turn on the power supply
6) Lift up the coil and yoke, observe the quantity
of iron filings that is lifted up and read off the
current. Enter the measured current and an es-
timate of the amount of iron filings lifted up
into Table 2.
7) Turn off the power supply, insert the core into
the coil with 800 windings and repeat the ex-
periment. Enter the results into Table 2.
8) Turn off the power supply when the experiment
is finished.
6 V
+
–
A
N N = 200 = 800
Fig. 2 Set-up for Sub-experiment 2
Sub-experiment 2: Evaluation
Table 2:
I in mA
Number of
windings N
Amount of fil-
ings lifted
580 200 Few
580 800 Many
Complete the following:
1) If the current, the length of the coil and the
material inside the coil all remain the same,
the larger the number of windings, the
greater
the force in the magnetic field of the coil.
Sub-experiment 3:
Set-up and procedure
1) Use the same set-up as in sub-experiment 1
using the coil with 800 windings and no yoke
(see Fig. 3a).
2) Set the knob on the power supply to 6 V and
turn it on.
3) Lift up the coil, observe the amount of filings it
lifts and enter the result into Table 3.
4) Insert the core into the coil and repeat the
experiment (see Fig. 3b).
5) Turn off the power supply when the experiment
is finished.
6 V
+
–
A
a)
b)
N = 800
Fig. 3 Set-up for sub-experiment 3
Sub-experiment 3: Evaluation
Table 3:
Number of
windings N
Inside coil
Amount of
filings lifted
800 Air Few
800 Core Many
Complete the following:
If the current, the number of windings and the
length of the coil all remain the same, an iron core
inside the coil causes the forces in the magnetic
field of the coil to
increase .
Note:
The force F exerted by a magnet is proportional to
the magnetic flux density
0 r
N
B µ µ I
d
˜ ˜ ˜ ,
where
µ
0
= magnetic field constant (permeability of free
space), µ
r
= relative permeability, I = current, N =
number of windings, d = length of coil. In our ex-
periment
we have shown that
B v I, B v N and B v P
r
.