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Correct OPTION is (c) LIMITING ERRORS of the three known resistances

Easy explanation: The MAIN SOURCE of error in a Wheatstone bridge is because of the limiting errors of the three known resistances. As a result very precise resistances are required with 1 % tolerance.

The CORRECT option is (a) ^R3 ⁄ R4 = 1

To explain I WOULD say: Under a small unbalance condition, the bridge SENSITIVITY equation becomes

Here E is the emf of the circuit. For maximum bridge sensitivity, we get R3=R4.

Right ANSWER is (d) \(S_B=\frac{\theta}{\frac{\DELTA R}{R}}\)

Easiest explanation: The bridge sensitivity is defined as the amount of deflection of the galvanometer per unit FRACTIONAL change in the UNKNOWN resistance.

\(S_B=\frac{\theta}{\frac{\Delta R}{R}}\)

Here ∆R/R denotes the fractional change in the unknown resistance.

Correct ANSWER is (c) DEGREES per volts

To explain: So the UNIT of VOLTAGE sensitivity is degrees per volts as deflection is measured in degrees and voltage is in volts.

Right answer is (C) mm/µA

The explanation: where, DEFLECTION is in mm and CURRENT is in µA.

So the UNIT of SENSITIVITY is mm/ µA.

The correct choice is (d) amount of DEFLECTION PER UNIT current

To ELABORATE: Sensitivity is expressed as

Thus sensitivity is defined as the amount of deflection per unit current.

The correct choice is (B) sensitivity

For explanation I would say: The amount of DEFLECTION of the GALVANOMETER depends upon its sensitivity. RESISTANCE of the ratio ARMS does not affect the amount of deflection of the galvanometer.

Correct option is (B) varying the resistance arms R1 and R2

The explanation is: The balance CONDITION in a Wheatstone bridge can be OBTAINED by varying the resistances R1 and R2. NULL detector is used for DETERMINING balance condition.

Correct answer is (a) ratio of arms R1 and R1

Easy EXPLANATION: The ratio of the arms R1 and R2 determines the BALANCE CONDITION of a WHEATSTONE bridge. The balance condition is given by the equation R4 = ^R3R1⁄R2.

The correct option is (a) 0

The explanation: Under bridge BALANCE condition, no current flows through the galvanometer. Current flow is independent of the values of RATIO ARMS R1 and R2.

The correct choice is (d) NULL deflection

To elaborate: The WHEATSTONE bridge works on the principle of null deflection. A galvanometer is USUALLY used for measuring the flow of current in the bridge CIRCUIT.

Right choice is (b) unknown resistance to be measured

The best I can explain: R4 is the unknown resistance whose value has to be found by comparison with a standard. R3 is known as the standard resistance. Resistance arm COMPRISES of four RESISTANCES including R1, R2, R3, and R4.

Right choice is (a) standard ARM

For EXPLANATION I would say: The arm consisting of the standard known resistance R3 is known as the standard arm. By making use of this resistance value the unknown resistance can be DETERMINED USING the balance CONDITION.

Correct choice is (c) BATTERY and GALVANOMETER

To explain: A battery is connected between the two ENDS of the WHEATSTONE BRIDGE while a galvanometer is connected between the opposite two ends of the circuit. Ammeter is connected in series with the circuit.

Right answer is (d) ratio arms

For explanation I would SAY: The arms consisting of the two resistances R1 and R2 are known as the resistance arms. SOURCES do not appear on the arms of the bridge and they are connected across OPPOSITE ends. Wheatstone bridge is purely resistive in NATURE.

Correct answer is (c) NULL detector

The BEST I can EXPLAIN: A galvanometer is used as a null detector to detect the flow of current ACROSS the ends of the two OPPOSITE junctions of the circuit. Voltage source is used for providing the required dc supply to the bridge.

The correct choice is (b) e.m.f and null detector

To explain I would say: The TWO OPPOSITE ends of a Wheatstone bridge CIRCUIT CONSISTS of a source of e.m.f and a null detector. Four arms of a Wheatstone bridge CONSIST of resistances. Inductance and capacitance do not appear in a Wheatstone bridge.

Right CHOICE is (C) pressure and temperature

To elaborate: In control applications, when ONE of the arms of the bridge circuit consists of a resistance element, sensitive PHYSICAL parameters such as pressure and temperature are to be controlled.

Correct CHOICE is (a) 4 RESISTIVE arms

For explanation: A Wheatstone bridge essentially consists of 4 resistive arms. The arms are such that two RESISTANCES appear across each END.

Right choice is (b) resistive element

The explanation is: One of the arms of a bridge circuit in GENERAL consists of a resistive element. CONTROL systems EMPLOY resistive ELEMENTS for industrial applications.

The CORRECT answer is (d) Wheatstone and Kelvin

The explanation is: Wheatstone and Kelvin are the commonly USED bridges for the measurement of resistance. WAGNER’s and De Sauty’s bridges are used for shielding the CIRCUIT.

Correct option is (c) control circuits

Explanation: The BRIDGE CIRCUIT is generally used in control applications. Control systems MAKE USE of bridge circuits for INDUSTRIAL applications.

Correct CHOICE is (a) HIGH

The best explanation: The MEASUREMENT is done by comparing the unknown value with a standard known value. Thus the measurement accuracy is high in a BRIDGE circuit.

Correct choice is (C) remains unchanged

The explanation: The balance condition is INDEPENDENT of the positions of the SOURCE and the detector. Source and detector can be connected across any two SETS of opposite ARMS of the bridge.

Right answer is (a) component values

Best explanation: The ACCURACY of the measurement of a bridge CIRCUIT depends on the values of the COMPONENTS used in it. Voltage source supplies dc bias to the circuit while the detector is used for balance condition.

The correct answer is (b) impedance values

For explanation: Impedance values are USED to characterize ONE port DEVICES, NETWORKS, multiport devices and other systems.

The correct answer is (a) measurement of RESISTANCE

The EXPLANATION: Resistance MEASUREMENTS are done by making USE of a suitable D.C. bridge.

Right choice is (d) balancing condition

The best I can explain: During BALANCE condition or EQUILIBRIUM there exists a certain relationship between the component VALUES of the four arms of the bridge. This relationship is known as the balancing condition or balancing EQUATION.

Correct choice is (B) BRIDGE components

For explanation I would say: As a bridge circuit COMPARES the value of an unknown component with the value of a STANDARD, it’s ACCURACY depends on the bridge components.

Correct choice is (c) When no current flows through the galvanometer

To EXPLAIN: The BRIDGE circuit is SAID to be BALANCED when no current flows through the null indicator which is GENERALLY a galvanometer.

The correct choice is (a) null indication

The explanation is: A bridge circuit operates on the PRINCIPLE of null indication. BASED on the DEFLECTION of the galvanometer, CURRENT FLOWS between the two opposite junctions.

The CORRECT choice is (d) comparison

To explain I would say: A bridge circuit MAKES USE of a comparison measurement method. In this method the bridge compares the value of an UNKNOWN COMPONENT with a standard value of a given component.

Right answer is (a) RESISTANCE, capacitance, and inductance

The EXPLANATION is: A bridge circuit is basically used for the measurement of basic ELECTRONIC COMPONENTS such as resistance, capacitance, and inductance.

The correct OPTION is (b) source of CURRENT

Explanation: A current source is connected between the two OPPOSITE junctions of a bridge circuit. Deflection of the galvanometer in the circuit indicates the flow of current.

Right OPTION is (c) 4 resistance arms

Best explanation: A SIMPLE bridge CIRCUIT is made of a network consisting of 4 resistance arms. Usually a galvanometer is connected between the ends of the OPPOSITE TWO junctions in order to measure the flow of current.