PASCO SF-8616_8617 COILS SET - Manual (Page 9)

scientific 7
012-03800A
Experiment 2: Transformer Basics II
Introduction
In this lab you will investigate several of the factors influencing the operation of a transformer. In
Experiment 1, the output factor was voltage as measured when there was nothing connected to the
secondary (infinite resistance). In this lab, you will investigate input and output currents, in
addition to voltages, with normal sized resistances in the secondary circuit.
Equipment Needed - Supplied
1. The four coils from the PASCO SF-8616 Basic Coils Set
2. The U-shaped Core from the PASCO SF-8616 Basic Coils Set
3. Optional: the additional coils from the PASCO SF-8617 Complete Coils Set
Equipment Needed - Not Supplied
1. Low voltage ac power supply 0-6 VAC, 0-1 amp such as PASCO Model SF-9582
2. One or two AC ammeters 0-2 A
3. Three resistors: 10
Ω
, 2 Watt; 100
Ω
, 2 Watt; 1000
Ω
, 2 Watt
4. Banana connecting leads for electrical connections
Procedure
1. Set up the coils, core and 1000-
Ω
load
resistor as shown in Figure 1. In the
diagram, the coil to the left will be referred
to as the primary coil, and the one to the
right will be the secondary coil. Note that
we provide an alternating current at the
primary at one voltage level, and read the
output at the secondary at possibly a
different value.
ac power
ac
amperes
ac
amperes
R
Primary Secondary
Figure 1
2. With the 400-turn coil as the primary and the 400-turn coil
as the secondary, adjust the input voltage to 6.0 volts a.c.
With a load resistance of 1000
Ω
connected to the
secondary, measure the input current, the output voltage
and the output current. Record your results in Table 2.1.
3. Repeat step 2 after connecting in a 100
Ω
load resistance.
4. Repeat step 2 after connecting in a 10
Ω
load resistance.
5. Finally, repeat steps 2-4 after changing the secondary coil.
Continue changing the coils until you have tested all
combinations of input and output coils.
6. Replace the secondary coil with a relatively large diameter
wire (18-20 gauge) wound around the core 5-6 times. See
Figure 2. Again set the input voltage to the primary at 6.0
vac. Connect the ammeter to this new secondary, measur-
ing the current when the resistance is only that of the
ammeter. With the ammeter disconnected, measure the
output voltage.
7. If you have the SF-8617 Complete Coils Set, arrange the
primary and secondary coils as shown in Figure 3. Run
the same set of experiments you did in steps 2-4, collect-
ing the same items of data.
Figure 2
Primary
Secondary
Figure 3