# Electrical Measurements Questions and Answers – Digital Multimeter

This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Digital Multimeter”.

1. Digital multimeter is used for _________
a) measuring a.c. and d.c. current, voltage and resistance
b) measuring a.c. current and voltage
c) measuring d.c. current and resistance
d) measuring a.c. voltage and resistance

Explanation: Digital multimeter is usually used for the measurement of a.c. current, voltage and resistance. It is also used for the measurement of d.c. current, voltage and resistance as well over several range.

2. Current is converted to voltage __________
a) through a voltmeter
b) through a resistance
c) through an ammeter
d) through a galvanometer

Explanation: Current is passed through a low shunt resistance and is converted to voltage. A.C. quantities are converted to D.C. through various rectifier and filter circuits. Voltmeter and ammeter are used for voltage and current measurement respectively.

3. For resistance measurement, meter contains _________
a) high current source
b) medium current source
c) low current source
d) low voltage source

Explanation: Usually in the measurement of resistance, meter consists of a precision low current source applied across an unknown resistance which gives a d.c. voltage.

4. Quantities are digitised using _________
a) D/A converter
b) oscillator
c) amplifier
d) A/D converter

Explanation: Quantities such as current, voltage and resistance are digitised by making use of an A/D converter. They are then displayed on the screen by making use of a digital display.

5. Analog mulimeters require power supply.
a) True
b) False

Explanation: Analog multimeters are less affected by electric noise and isolation problems. As a result analog multimeters don’t require a power supply.
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6. Output of a digital multimeter is _________
a) mechanical
b) optical
c) electrical
d) analog

Explanation: Digital multimeter gives an electrical signal as the output. A/D converter is employed for the conversion from analog to digital signal. This can be used for interfacing with external equipment.

7. Basic building blocks of digital multimeter are _________
a) oscillator, amplifier
b) diode, op amp
c) rectifier, schmitt trigger
d) A/D, attenuator, counter

Explanation: Usually dual slope integrating type ADC is preferred in multimeter. It basically consists of several A/D converters, counter circuits and an attenuation circuit.

8. Resistance is measured using _________
a) constant current source
b) constant voltage source
c) variable current source
d) variable voltage source

Explanation: Constant current source is used to measure resistance in a digital multimeter. Standard known value of current is passed through an unknown resistance and the drop in voltage across the resistance is measured.

9. A.C. voltages are measured using _________
a) oscillators and op amps
b) rectifiers and filters
c) resistor and capacitor
d) inductor and resistor

Explanation: Rectifiers and filter circuits with various configurations are employed for measuring A.C. voltages. A.C. is converted to D.C. and is applied to the A/D converter.

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