PASCO SF-9500A STUDENT GALVANOMETER - Manual

Instruction Sheet
for the PASCO
Model SF-9500A
STUDENT GALVANOMETER
012-07749A
© 2001 PASCO scientific
Introduction
The PASCO SF-9500A Student Galvanometer is a
rugged, yet sensitive instrument, designed specifically
for student experiments. It has a center-zero meter that
ensures easy determination of polarity, and three
current ranges. A “Push-To-Read” switch protects the
meter during hookup by shunting the current through
an equivalent resistor. When performing a null-current
experiment, such as measuring resistance using a
Wheatstone bridge, it is easy to balance the current
using the 5 mA range, then stepping down through the
lower current ranges to very accurately determine the
point of zero current.
PUSH
TO
READ
5 mA
500 mA
SF-9500A
50 mA
Galvanometer
40
0 20
20
40
0
CE
®
Operation
To zero the meter:
Place the meter in the position in which it will be
used, vertically or horizontally. Disconnect the meter.
Use a small, flat-head screwdriver to turn the zero-
adjust screw (located on the meter housing below the
meter) until the meter needle aligns with the zero
mark on the scale.
NOTE: If the position of the meter changes after it is
mechanically aligned, the meter may need to be zeroed
again.
To measure current:
1. Connect the circuit between the negative terminal
of the galvanometer and the red input connector
with a current rating greater than the expected
current.
NOTE: It is a good idea to begin with the 5 mA
range, then step down to the lower ranges as
required. The meter is protected while you make
the connections, because the current does not pass
through the meter. Instead it passes through a
parallel shunt resistor that has the same resistance
as the meter.
2. When the connections are made, and you are ready
to measure the current, press and hold the PUSH
TO READ button.
3. Now read the current on the meter
The current ranges displayed beside the input
connectors refer to the current value that will give a
full-scale meter deflection. For example, a meter
reading of +40 in the 5 mA range indicates a current of
4 mA flowing through the galvanometer. A reading of
–40 indicates that 4 mA of current is flowing in the
opposite direction.