Q57. What is the reason for having a mirror on the scale of a multimeter?
Q58. How is the mirror on a multimeter used?
Q59. List the 11 safety precautions for multimeters.
In addition to the ammeter, voltmeter, ohmmeter, and multimeter, you will probably use many other
types of measuring devices. Many of those measuring devices (test equipment) are discussed later in this
training series. The following brief discussion of a few additional meters will introduce you to some of
common measuring devices you will use in working on electrical and electronic circuits.
HOOK-ON TYPE VOLTAMMETER
The hook-on ac ammeter consists essentially of a current transformer with a split core and a rectifier-
type instrument connected to the secondary. The primary of the current transformer is the conductor
through which the current to be measured flows. The split core permits the instrument to be "hooked on"
the conductor without disconnecting it. Therefore, the current flowing through the conductor may be
measured safely and easily, as shown in figure 1-43.
Figure 1-43.A hook-on type voltammeter.
The instrument is usually constructed so that voltages also may be measured. However, in order to
read voltage, the meter switch must be set to VOLTS, and leads must be connected from the voltage
terminals on the meter to terminals across which the voltage is to be measured.