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Correct choice is (a) Q = \(\FRAC{(C_1 – C_2 ) Q_1 Q_2}{Q_1 C_1 – Q_2 C_2}\)

The explanation: ωL = \(\frac{1}{ωC}\)and Q1 = \(\frac{ωL}{R} = \frac{1}{ωC_1 R}\)

XS = \(\frac{C_1-C_2}{ωC_1 C_2 }\), RS = \(\frac{Q_1 C_1 – Q_2 C_2}{ωC_1 C_2 Q_1 Q_2}\)

QX = \(\frac{X_S}{R_S}= \frac{(C_1- C_2) Q_1 Q_2}{Q_1 C_1-Q_2 C_2}\).

Right OPTION is (b) Q = \(\frac{(C_2 – C_1 ) Q_1 Q_2}{Q_1 C_1 – Q_2 C_2}\)

Best EXPLANATION: \(\frac{1}{R_P}= \frac{ωC_1}{Q_2} – \frac{1}{RQ_1^2}\), XP = \(\frac{1}{ω(C_2 – C_1)}\)

Q = \(\frac{(C_2 – C_1 ) Q_1 Q_2}{Q_1 C_1 – Q_2 C_2}\).

The correct option is (c) Measure quality factor of CAPACITOR and inductor

The best I can explain: Q-Meters are intended to measure the quality factor of a capacitor and inductor. Q = \(\FRAC{Lω}{R} = \frac{1}{ωCR} = \frac{V_C}{V_A}\). They are not used for MEASURING capacitances and inductances, unlike AC Bridges.

Correct answer is (d) Q factor of an INDUCTIVE coil, the effective RESISTANCE, and bandwidth

To explain I would say: Q meter can measure the Q factor of an inductive coil. It can ALSO measure the effective resistance. Also, the bandwidth can be MEASURED by the Q Meter. Therefore it can be used for all the above FUNCTIONS.

The correct ANSWER is (c) 150

Easiest explanation: Q = \(\frac{ω}{ω1 – ω2} = \frac{f}{F2-f1}\)

Here, f = 1.5 × 10^6 Hz

f1 = (1.5 × 10^6 – 5 × 10^3)

f2 = (1.5 × 10^6 + 5 × 10^3)

So, f2 – f1 = 10 × 10^3 Hz

Q = \(\frac{1.5 × 10^6}{10 × 10^3}\) = 150.

Correct option is (c) \(\frac{C_3-4C_4}{3}\)

For explanation I would say: QX = \(\frac{R_P}{X_P}= \frac{(C_4 – C_3)Q_3 Q_4}{Q_3 C_3 – Q_4 C_4}\)

The MAIN error in the MEASUREMENT of Q is due to the distribution. To check for this, the Q value is measured at two frequencies f1 and 2f2. It should be same, if not then, \(\frac{C_3-4C_4}{3}\).

Correct option is (a) Series RESONANCE

The explanation: We KNOW that Q = \(\frac{ωL}{R}\)

From the above relation, we can say that it WORKS on series resonance.

Correct option is (d) L = \(\frac{1}{(2πf)^2 C}\)

The best EXPLANATION: Coil inductance in a Q meter is given by the relation,

L = \(\frac{1}{(2πf)^2 C}\)

where, f is the frequency in Hz

C is the CAPACITANCE in F.

Right answer is (c) THERMOCOUPLE

Best explanation: A thermocouple is used for measuring the voltage ACROSS a shunt resistance in a practical Q meter. Electronic voltmeter is used for the measurement of voltage across a RESONANT CAPACITOR.

Correct answer is (c) RF oscillator

To explain: Practically a Q meter CONSISTS of a wide range RF oscillator with a FREQUENCY range of 50 kHz to 50 MHz. Oscillator acts as a SOURCE and delivers CURRENT to a low shunt resistance.

Right answer is (b) Q = \(\frac{X_L}{R}=\frac{X_C}{R}=\frac{E_C}{E}\)

The EXPLANATION: The applied VOLTAGE E is inversely proportional to the Q factor of a CIRCUIT and is given by the RELATION,

Q = \(\frac{X_L}{R}=\frac{X_C}{R}=\frac{E_C}{E}\).

The correct option is (a) Q = \(\frac{X_L}{R} = \frac{X_C}{R}\)

Explanation: Q FACTOR in a SERIES resonant CIRCUIT is given by the relation,

Q = \(\frac{X_L}{R} = \frac{X_C}{R}\)

where, R is resistance of the coil

XC is the capacitive reactance

XL is the inductive reactance.

The correct ANSWER is (d) series resonance

Easy explanation: Q METER basically operates on the CHARACTERISTICS of a series resonant coil. In a series resonant circuit the voltage drop across the coil or a CAPACITOR is equal to the APPLIED voltage multiplied by its Q factor.

The correct option is (c) INSTRUMENT

Best EXPLANATION: Q METER is basically an instrument that is used for the measurement of ELECTRICAL properties of capacitors and coils. It is also used as a laboratory instrument.

The correct ANSWER is (B) reactance to resistance

For EXPLANATION: Q factor can also be obtained as the ratio of reactance to resistance of an ELEMENT. For inductive element it is the ratio of XL to R and for a CAPACITIVE element it is the ratio of XC to R.

Right ANSWER is (a) Quality factor

For explanation I WOULD say: Q factor is also known as Quality factor or storage factor. It is BASICALLY a ratio of the power STORED in an ELEMENT to the power dissipated in that element.

Correct answer is (a) constant current source

For explanation I would say: 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.

The CORRECT choice is (b) rectifiers and filters

To elaborate: 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.

The correct option is (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.

Correct ANSWER is (b) False

The best I can EXPLAIN: Analog multimeters are less AFFECTED by ELECTRIC noise and isolation problems. As a result analog multimeters don’t REQUIRE a power supply.

Right CHOICE is (c) low CURRENT source

To explain: 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.

Right choice is (d) A/D converter

The 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.

The correct ANSWER is (b) through a resistance

The explanation is: 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.

The correct answer is (a) measuring a.c. andd.c. CURRENT, 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.

Right choice is (B) False

Explanation: RANGE relays are set through the decoder using the NEW INFORMATION obtained with the help of a clock PULSE. Decimal point is also changed as per the requirement of the new range.

Correct option is (C) stored in a flip-flop

Explanation: The OUTPUT from the INTEGRATOR is used to set a polarity flip-flop. The flip-flop’s output is then stored in MEMORY until the next measurement of voltage is obtained.

Correct answer is (a) True

The best I can explain: ADC contains INFORMATION required for polarity indication. The polarity of the signal that is integrated is of UTMOST importance.

The correct option is (d) contains information

For explanation: When the count PRODUCED by the ADC counter is less than 170, a control pulse is OBTAINED for down ranging. Whereas the control pulse for up ranging is produced once the ADC counter EXCEEDS 1999 units.

Right answer is (C) automatically SWITCH range

The explanation is: The DVM should automatically switch its range when the display is GREATER than 1999 UNITS as it is the maximum set limit for achieving a higher sensitivity.

Correct choice is (b) reduction by a factor

Explanation: A 3 digit DISPLAY DVM with maximum READING CAPABILITY indicates that any reading above the maximum set limit of 1999 will be reduced by a factor of 10.

Correct answer is (d) manually

The best I can explain: A manual range hold command is USED to control the CLOCK PULSES and the autoranging. This is done through a signal that exceeds the MAXIMUM range for up counts by reaching the most SENSITIVE range (down counts).

Right answer is (b) ± 0.035 V

Best EXPLANATION: The resolution of a DVM is,

R = ^1⁄10^N

Here, n is 3. SUBSTITUTING n=3 in the equation for resolution we get,

R = ^1⁄10^3 = 10^-3 = 0.001

For 10 V range, the resolution is,

R10V = 10 × 0.001 = 0.01 V

Consider the reading of 5 V.

Error = ± 0.5 % of 5 = ^0.5⁄100 × 5 = ± 0.025 V

1 digit error = ± 0.01 V

 Total error = ±(0.025 V+ 0.01 V)=± 0.035 V.

Right answer is (C) S = (fs)min × R

Best EXPLANATION: Sensitivity of the DVM is obtained from the relation,

S = (fs)min × R

where, S is the sensitivity

R is the resolution

(fs)min is the full scale value on minimum range.

The CORRECT answer is (a) R = ^1⁄10^n

Explanation: The RESOLUTION of a DVM is,

R = ^1⁄10^n

where, n is the number of FULL digits

R is the resolution.

Right choice is (a) 9999

For explanation: In a DUAL slope integrating type DVM, the electronic counter reaches a maximum VALUE of 9999 before resetting. A carry pulse is generating pulling down all the DIGITS to ZERO. Flip-flop then activates the control logic.

The CORRECT option is (d) zero

To explain I would say: In a dual slope integrating TYPE DVM, the electronic counter is reset to 0 at the beginning of the measurement of VOLTAGE. Flip-flop output is also maintained at zero and is given to control logic.

Correct choice is (a) no effect

For explanation: In the dual slope integrating type DVM method, the CAPACITOR is connected through means of an electronic SWITCH. As a result the effects due to OFFSET voltage wherein there exists an OUTPUT voltage without the application of any input are eliminated.

Correct OPTION is (b) False

Explanation: In a dual slope INTEGRATING type DVM, the noise is CANCELLED out by the POSITIVE and negative ramps during the process of integration. As a RESULT, the noise rejection is excellent.

Correct answer is (d) time-period

The best explanation: The INPUT VOLTAGE in a dual slope INTEGRATING type DVM is given by the relation,

Vin = Vref ^t2 ⁄ t1

From the above equation it is seen that the input voltage in a dual slope integrating type DVM depends on the time periods t1 for which the capacitor is charged and t2 during which the capacitor is discharged.

The CORRECT option is (c) integral of the input

To explain: In a dual slope INTEGRATING type DVM, the output voltage is given by the integral of the input voltage.

where, Vin is the input voltage

R1 is the series resistance

t1 is the time for which the CAPACITOR is charged.