Digital Voltmeters MCQ Quiz in मल्याळम - Objective Question with Answer for Digital Voltmeters - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is option 1): (5 KΩ/V)

Concept:

• Sensitivity is defined as the deflection per unit current flowing in the coil. The sensitivity of the voltmeter also depends on the circuit resistance which is known as the loading effect.
• DC Sensitivity(SDC): Deflection per unit DC current flowing in the coil.

\({S_{DC}} = \frac{1}{{{I_{fs}}}}(Ω /V)\)

• Where I_fs = Full-scale deflection current

Calculation:

Given

I_fs = 200 μA

• From equation (1),
• Sensitivity can be calculated:     \({S_{DC}} = \frac{1}{{{200 \ μA}}}(Ω /V)\)  = 5 kΩ/V 

The correct answer is option 3):(19999)

Concept:

There are two types of digits in a digital voltmeter:

• Full Digit
• Half Digit ​

Full Digit:

A Full digit can take any value from 0 to 9.

It is having a total of 10 different states, i.e. a full digit may have any value 0, 1, 2,...or 9.

Half digit:

Half a digit can have a value of either 0 or 1.

This digit is the most significant digit. 

\(4\frac{1}{2}\) Digit Display have five digits with 1 Half digit (0 or 1) and 4 Full digits.

The range of display will be from 0 to 19999.

This is explained as shown:

The 1 V range can read up to 1.9999

Concept:

Digital instruments:

Definition: Instruments that are used to express the measuring quantity in numeric format is known as Digital Instruments.

Principle: Quantization is the basis of the working of a digital instrument. It is an act of transforming an analog signal into its digital form.

Advantages of Digital Instruments:

• Highly accurate measurement.
• Numeric data representation format provides better readability.
• Energy consumption is very less.
• Better resolution: Reading may be carried to any number of significant figures by merely positioning the decimal point

Manual setting of polarity and zeroing is required in analog meters which is a disadvantage for analog meters and it was automatically adjusted in digital instruments.

Concept:

Sensitivity of voltmeter is given by,

\(s = \frac{1}{{{I_{FSD}}}}\)

Where IFSD is full-scale deflection.

Calculation:

Sensitivity, \(s = 1000\;{\rm{\Omega }}/v\)

Full-scale deflection current is reciprocal to the sensitivity.

\({I_{FSD}} = \frac{1}{s}\)

\({I_{FSD}} = \frac{1}{{1000}} = 1\;mA\)

Concept:

The resolution (R) of an N-bit digital voltmeter is given by:

\(R = {Range \over 10^N}\)

The range is defined as the sum of the smallest and largest numbers that can be displayed.

Calculation:

Given, N = 3

\(R = {1 \over 10^3}\)

Resolution = 0.001

Concept:

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

 \(R= \frac{1}{{{{10}^N}}} \)× range of the voltmeter

Where N is the number of full digits. 

In a DVM, a full digit counts 0 to 9 and a half digit counts from 0 to 1.

Calculation:

The full-scale reading = 9.99 V

Total counts = 1000

It is a 3-digit voltmeter i.e. N = 3.

Range of voltmeter = 10 V

Resolution for the given DVM is

 \(= \frac{1}{{{{10}^3}}} × 10 = 0.01 \;V\)

In a 4½ digit voltmeter,

number of full digits are = 4

number of half digits = 1

Full digit can read from 0 to 9

Half digit can read from 0 to 1

Hence the largest number can be read is 19999

Concept:

The resolution in a N bit DVM is given by \(= \frac{1}{{{{10}^N}}} \times range\;of\;voltage\)

Where N is the number of full digits.

In a DVM, a full digit counts 0 to 9 and half digit counts from 0 to 1.

Calculation:

The given DVM has 4 ½ digit display, i.e. it has 4 full digits and 1 half digit.

Resolution for the given DVM is \(= \frac{1}{{{{10}^4}}} \times 1 = 0.0001\)

Minimum count for the given DVM = 0.0001

Maximum count = 1.9999 V

Tips and Tricks:

From the given options, only option 2 has four and half digit display.

Important:

A half digit doubles the existing range.

In the given question, the range is 1 V.

As one half digit present, it doubles the range i.e. the range becomes 2 V.

So, the maximum reading = 1.9999 V

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