# Digital Voltmeter MCQ || Digital Voltmeter Questions and Answers

1. Digital voltmeters converts ________

1. Analog to digital signal
2. Digital to analog signal
3. Current to voltage
4. Resistance to voltage

Explanation:

Digital Voltmeter (DVM): A digital voltmeter is also called a digital electronic voltmeter, it measures and displays dc or ac voltages as a discrete number instead of a pointer deflection on a continuous scale. It requires an analog to digital converter (AD to converter the analog value into a digital value.

2. A voltmeter connected across 15 kΩ resistor reads 10 V. Voltmeter is rated at 500 Ω / volt and has a full-scale reading of 20 V. The supply voltage is: 1. 60 V
2. 45 V
3. 30 V
4. 90 V

Explanation:

Sensitivity of voltmeter = 500 Ω/V

Internal resistance of voltmeter = 500 × 20 = 10 kΩ Effective resistance across A – B is

= 10 || 15 = 6 kΩ

The voltmeter reading is 10 V

⇒ VAB = 10 V

By voltage division,

Vs[6/(30 +6)] = 10

Vs = 60 V

3. Digital voltmeters can be used to measure ________

1. Voltage only
2. Voltage, temperature, pressure, etc
3. Voltage and current
4. Voltage and resistance

Explanation:

The digital voltmeters convert the analog signals into a digital signal and display the voltages to be measured as discrete numerical instead of pointer deflection on the digital displays.

The digital voltmeter can be used to measure a.c. and d.c. voltages and also to measure the quantities like pressure, temperature, stress, etc. using a proper transducer and signal conditioning circuit.

The transducer converts the quantity into the proportional voltage signal and the signal conditioning circuit brings the signal to the proper limits which can be easily measured by the digital voltmeter. The output voltage is displayed on the digital display on the front panel.

4. Which of the following is an advantage of the analog multimeter over the digital multimeter?

2. High accuracy
3. Smaller size
4. Less electric noise

Explanation:

Digital multimeters have the following advantages over analog multimeters:

• More accurate
• Reduced reading and interpolation errors
• Parallax error is eliminated
• Faster and do not require zero adjustment
• Smaller size therefore portable

5. A digital voltmeter reduces ______

1. Parallax Error
2. Ageing Error
3. Both 1 and 2
4. None of the above

Explanation:

Parallax refers to the change in the apparent position of an object when viewed from different points. Due to the digital display, the human reading errors, interpolation errors, and parallax errors are reduced.

6. A 3(1/2) digit voltmeter has a resolution of

1. 0.01% of the full range
2. 0.05% of the full range
3. 0.1% of the full range
4. 0.5% of the full range

Answer:4. 0.5% of the full range

Explanation:

The resolution (R) in an N bit DVM is given by:

R = Range of voltmeter/10N

Where N is the number of full digits.

Given that,

N = 3(1/2)

R = 1/(2 × 103)

%R = (1/2000) × 100 × of full range

%R = 0.05 % of full range

7. In a Digital voltmeter, a transducer converts ________

1. Input to a proportional current
2. Input to a proportional power
3. Input to a proportional voltage
4. Input to a proportional resistance

Answer:3. Input to a proportional voltage

Explanation:

The digital voltmeters convert the analog signals into a digital signal and display the voltages to be measured as discrete numerical instead of pointer deflection on the digital displays.

In a digital voltmeter, a transducer is used.

The transducer converts the quantity into the proportional voltage signal and the signal conditioning circuit brings the signal to the proper limits which can be easily measured by the digital voltmeter.

8. In a digital voltmeter, during start of conversion, zero indication is displayed and is called auto zeroing. This is achieved by

1. Using a positive reference voltage
2. Using a negative reference voltage
3. Properly charging the differentiator circuit capacitance to ground
4. Properly discharging the integrator circuit capacitance to ground

Explanation:

In a digital voltmeter, during the start of conversion, zero indication is displayed. This is known as auto zeroing. It consists of an integrator. To achieve auto zeroing, the switch S is connected from Vin to the ground potential and the capacitor C of the dual-slope integrator discharges to the ground.

9. In a DVM, a signal conditioning circuit is used to  ________

1. Bring current to a suitable limit
2. Bring resistance to a suitable limit
3. Bring resistance to suitable limit
4. Bring voltage to a suitable limit

Answer:4. Bring voltage to a suitable limit

Explanation:

The main function of a signal conditioner is to pick up the signal and convert it into a higher level of an electrical signal.

In a digital voltmeter, the transducer converts the quantity into the proportional voltage signal and the signal conditioning circuit brings the signal voltage to the proper limits which can be easily measured by the digital voltmeter.

10. An unknown DC voltage is to be measured. Which measuring range in the multimeter will you select first?

1. 500 V
2. 50 V
3. 5 V
4. 0.5 V