A22. Since the ammeter is a resistor in series with the load, it increases the resistance of the circuit and
lowers circuit current.
A23. The resistance of the ammeter must be much smaller than the circuit load.
A24. The amount of current that will cause full-scale deflection.
A25. Shunt resistors (internal or external).
A26. To prevent damage to the meter movement from excessive current.
A27. A range that allows a meter reading near the center of the scale.
a. Always connect an ammeter in series.
b. Always start with the highest range.
c. In dc ammeters, observe the proper polarity.
d. Deenergize and discharge the circuit before connecting or disconnecting the ammeter.
e. Never use a dc ammeter to measure ac current.
Observe the general safety precautions of electric and electronic devices.
A29. Since the ammeter has a small resistance compared to the load, it will have very high current if it
is connected in parallel. This high current will damage the meter.
A31. In parallel.
A32. The connection of a voltmeter adds a resistance in parallel with the circuit changing the total
circuit resistance, and loads the circuit.
A33. A voltmeter must have a high resistance compared to the circuit being measured.
A34. Since the resistance of a meter movement remains the same as the pointer is deflected, the amount
of current through the movement is proportional to the voltage applied. Therefore, only the scale of
the movement must be changed.
A35. It is an indication of the resistance of the meter expressed in ohms per volt. The total resistance of
the meter is the sensitivity multiplied by the full-scale voltage.
A36. The use of resistors in series with the meter movement.
A37. To prevent excess current through the meter movement.
A39. High-voltage measurement.