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:
3. Digital voltmeters can be used to measure ________
Voltage only
Voltage, temperature, pressure, etc
Voltage and current
Voltage and resistance
Answer:2. Voltage, temperature, pressure, etc
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?
No loading effect
High accuracy
Smaller size
Less electric noise
Answer: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 ______
Parallax Error
Ageing Error
Both 1 and 2
None of the above
Answer:1. Parallax Error
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
0.01% of the full range
0.05% of the full range
0.1% of the full range
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 ________
Input to a proportional current
Input to a proportional power
Input to a proportional voltage
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
Using a positive reference voltage
Using a negative reference voltage
Properly charging the differentiator circuit capacitance to ground
Properly discharging the integrator circuit capacitance to ground
Answer:3. Inter-symbol interference
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 ________
Bring current to a suitable limit
Bring resistance to a suitable limit
Bring resistance to suitable limit
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?
500 V
50 V
5 V
0.5 V
Answer:1. 500 V
Explanation:
A multimeter can be used to measure voltage, current, resistance, continuity, and other parameters
To measure an unknown D.C voltage, start by selecting the highest voltage on the dial (multimeter) and then turn down to a lower voltage if the voltage measured is seen to be low
If our selected range is lower than the reading, then the meter can’t be able to measure, Hence, we need to choose the highest possible range at the start
Here in the options, the highest possible voltage range is 500 V
