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The correct choice is (a) Inductance

The best explanation: For measuring Capacitance De-Sauty’s Bridge and Schering Bridge should be used. For measuring FREQUENCY WIEN’s Bridge is used. For measuring MUTUAL Inductance Heaviside and Campbell’s Bridge are used.

Correct option is (a) 375 Ω and 75 mH

The best I can explain: APPLYING the usual BALANCE condition relation,

Z1 Z4 = Z2 Z3

We have, (R1 + jL1 ω) \(\frac{R_4/jωC_4}{R_4+1/jωC_4}\) = R2 R3

Or, R1 R4 + jL1 ωR4 = R2 R3 + j R2 R3 R4 C4 ω

∴ R1 = 2000 × \(\frac{750}{4000}\) = 375 Ω

∴ L1 = 2000 × 750 × 0.5 × 10^-6

= 75 mH.

Right choice is (d) The Inductance of a COIL with a large time constant

The explanation is: CAREY – Foster slide-wire is suited for the COMPARISON of resistances which are nearly equal. The SCHERING Bridge is suited for Low values of capacitance. The Kelvin double bridge is used for measuring RESISTANCE in the milliohm range. Hay’s Bridge is suited for the measurement of Inductance of a coil with a large time constant.

Correct option is (a) MAXWELL’s BRIDGE

The best explanation: The GIVEN figure is Maxwell’s Bridge because it consists of two INDUCTORS. It is also used to measure the inductance of the INDUCTOR.

Correct OPTION is (a) Inductance cannot be MEASURED over a wide RANGE

To explain: Maxwell Bridge cannot be used for the MEASUREMENT of high Q values.

We have, Q = \(\frac{1}{ωR_X C_X} = \frac{ωL_X}{R_X}\)

Hence, Q ∝ LX

∴ Inductance cannot be measured over a wide range.

Right ANSWER is (d) Bridge cannot be balanced with the given configuration

For explanation: For Bridge to be balanced, the PRODUCT of IMPEDANCES of the opposite arm should be equal in magnitude as WELL as phase angle. Here Z3 Z2 ≠ Z1 Z4 for whatever CHOSEN value. Therefore the Bridge cannot be balanced.

Correct OPTION is (b) coils with low Q VALUES

To ELABORATE: The Maxwell inductance capacitance bridge is basically used for the measurement of quality factor (Q) of inductance coils with low Q values.

The correct answer is (a) CAPACITANCE bridge

Best explanation: A Wagner earth device is generally used for SHIELDING and grounding purpose. It consists of capacitances in the ratio arms along with a series RC combination connected across the ENDS of the bridge forming a potential DIVIDER.

Correct ANSWER is (B) SERIES RC combination

The best I can explain: The series combination of R and C in a Wagner earth device forms a potential divider across the ratio ARMS. It is also KNOWN as the guard arm.

The correct option is (d) by using Wagner DEVICE

The EXPLANATION is: A Wagner earthing device is used in general to eliminate the stray capacitance effects in AC bridges. The stray capacitance effects between the components in the ratio arms with respect to ground can be eliminated through this METHOD.

Right CHOICE is (c) shielding and GROUNDING

Explanation: The stray CAPACITANCE effects in an AC bridge can be eliminated by shielding and grounding. This method helps in MAKING the stray capacitances constant in value. They can be compensated.

Right answer is (b) False

To EXPLAIN: Stray CAPACITANCES are uncertain in nature. Their MAGNITUDE depends on the adjustment of the BRIDGE ARMS and the position of the operator.

Right ANSWER is (a) lumped inductances

For EXPLANATION I would say: AC BRIDGES in GENERAL such as Maxwell, Anderson, Schering, etc consist of lumped components such as inductance.

Correct answer is (a) True

For explanation: In general in AC BRIDGES, STRAY CAPACITANCE exists between the components of the bridge with respect to the ground. These stray capacitances short the ratio arms and lead to errors in the measurement.

Correct choice is (a) inductances in the range of 1 to 1000H

For EXPLANATION: BASICALLY a Maxwell bridge is used for the measurement of inductance in TERMS of known STANDARD capacitance value. Inductances in the range of 1 to 1000H with an accuracy range of ±2% can be MEASURED.

Correct OPTION is (d) low Q values

To elaborate: A Maxwell INDUCTANCE capacitance bridge can be used for the MEASUREMENT of low Q values only of the order of 1 to 10. This is because at HIGH Q FACTOR values the angular balance condition is not satisfied.

The correct option is (a) True

Explanation: The resistance R1 in a Maxwell inductance CAPACITANCE bridge can be calibrated directly. As a RESULT the value of the unknown inductance can be READ directly.

Right option is (c) by calibration

For explanation I would SAY: The RESISTANCE R1 in a Maxwell inductance capacitance BRIDGE can be scaled through calibration. The value of the Quality factor Q can be read directly through calibration.

Right choice is (a) independent of LOSSES in inductance

To explain: The balance equation in a MAXWELL inductance capacitance bridge is independent of the losses ASSOCIATED with an inductance. ACCORDING to the balance equation the unknown inductance is computed as LX = R2 R3 C1.

Right choice is (c) they are cheap

To EXPLAIN I would say: In a Maxwell inductance capacitance bridge, the capacitors are CHEAPER when compared to a STABLE and ACCURATE standard VALUE of inductors.

Correct answer is (b) False

The explanation: When the current flow through the STANDARD INDUCTANCE is adjusted PRECISELY, it provides its RATED value of inductance.

Correct choice is (B) False

To explain: STRAY magnetic FIELDS are present in a CIRCUIT consisting of inductances and capacitances. In order to eliminate the stray magnetic fields proper shielding is required for the standard inductance.

Right answer is (b) RX = \(\frac{R_2 R_3}{R_1}\)

For explanation I would say: The BALANCE condition for determining the value of the UNKNOWN RESISTANCE is given by the relation Rx = \(\frac{R_2 R_3}{R_1}\)

where, R1 and R3 are variable resistances and R2 is a fixed resistance.

Right answer is (c) Lx = R2 R3 C1

Explanation: The balance EQUATION for determining the value of the UNKNOWN INDUCTANCE is given by the RELATION Lx= R2 R3 C1.

where,

C1 is the capacitance across the RESISTANCE R1

R3 is a variable resistance and R2 is a fixed resistance.

Correct CHOICE is (a) MEASUREMENT of inductance

To elaborate: A Maxwell inductance capacitance BRIDGE is used for the measurement of inductance by making comparison with a standard capacitance value. VOLTMETER is used to MEASURE voltage, while an ammeter is used to measure current.

Right CHOICE is (a) independent

Explanation: In a high voltage Schering bridge, the balance equation does not depend on the FREQUENCY of OPERATION of the circuit. A DETECTOR is only used for detecting the balance CONDITION in a bridge circuit.

Right answer is (c) by USING a Wagner ground connection

For explanation: In a high voltage Schering BRIDGE, the effect of earth CAPACITANCE on the circuit including the GALVANOMETER and the CONTACT leads is minimized by making use of a Wagner ground connection.

The correct ANSWER is (a) True

For explanation I would say: In a high VOLTAGE Schering bridge the ratio arms have high IMPEDANCE values. As a result, a very small CURRENT is drawn by the ratio arms. Hence the detector must be very sensitive in a high voltage Schering bridge.

The correct option is (c) vibration galvanometer

The best EXPLANATION: A HIGH voltage Schering BRIDGE is used for the measurement of low CAPACITANCE values at high voltages. A vibration galvanometer is used as a detector in a high voltage Schering bridge.

The correct choice is (a) by using a STEP up transformer

Explanation: HIGH voltage SUPPLY for a SCHERING bridge is obtained by making use of a step up transformer. The frequency for the high voltage supply used in a Schering bridge is 50 Hz.

The correct answer is (b) False

The best I can explain: When a Schering bridge is USED for the MEASUREMENT of small capacitances at low voltages, it comprises of errors. In ORDER to avoid this a HIGH VOLTAGE Schering bridge is used.

Right answer is (b) 100pF to 1μF

Best EXPLANATION: Commercial Schering bridges are used for the measurement of capacitances in the range of a few pico farads to a few MICRO farads. Accuracy VARIES in the range of –2% to +2%.

Right option is (a) True

For explanation I would SAY: DISSIPATION factor for a circuit is DEFINED as the RECIPROCAL of the quality factor.

It is given by the EXPRESSION Q = ^1⁄wCR. It basically provides information about the quality of a capacitor.

The CORRECT choice is (c) Q = ^X⁄R

For explanation: The quality FACTOR the Schering bridge CIRCUIT is defined as Q = ^X⁄R.

where, X = ^1⁄wC is the CAPACITIVE impedance.

Right option is (b) tan⁡ δ = ωR4 C4

To explain: The expression for the loss angle can be COMPUTED as the RATIO of the TANGENT of the voltage drop across resistance RX to the voltage drop across the capacitance Cx.

Correct answer is (a) voltage between SERIES RC combination and C

Explanation: In a series RC circuit, δ refers to the ANGLE between the series combination of Rx, CX and the voltage across the CAPACITANCE Cx. δ is also KNOWN as the loss angle.

Right option is (c) p.f. = cos∅x = ^RX⁄Zx

Easy explanation: The power FACTOR of the RC combination in a Schering BRIDGE is given by the relationp.f. = cos∅x = ^Rx⁄Zx .

where,

Rx is the series resistance

Zx is the series IMPEDANCE comprising of Rx and Cx.

The correct OPTION is (d) p.f. = ωRx Cx

The best explanation: When PHASE angle reaches 90°, reactance EQUALS the impedance and the power factor of the BRIDGE is calculated USING the relation,

The correct CHOICE is (b) low and high voltages

Best EXPLANATION: Schering bridge is used for both low as well as high voltages. A particular bridge connection is used for low VOLTAGE. High voltages EMPLOY the use of a different type of Schering bridge.

Right option is (a) True

To elaborate: Schering bridge is an AC bridge USED for the measurement of unknown capacitance, dielectric loss and POWER factor. It is one of the most COMMONLY used AC bridges.