Electrical Measurements & Measuring Instruments Multiple Choice Questions on “Wheatstone Bridge Balance Condition”.
1. Wheatstone bridge consists of _________
a) 4 resistive arms
b) 2 resistive arms
c) 6 resistive arms
d) 8 resistive arms
Clarification: A Wheatstone bridge essentially consists of 4 resistive arms. The arms are such that two resistances appear across each end.
2. A galvanometer is used as a _________
a) current source
b) voltage source
c) null detector
d) input impedance
Clarification: 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.
3. The opposite two ends of a Wheatstone bridge consist of _________
a) voltage and current source
b) e.m.f and null detector
c) resistance and capacitance
d) inductance and impedance
Clarification: 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.
4. The arms consisting of the resistances R1 and R2 are called _________
a) resistance arms
b) impedance arms
c) source arms
d) ratio arms
Clarification: 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.
5. The arm consisting of the standard known resistance R3 is known as __________
a) standard arm
b) resistance arm
c) accurate arm
d) known arm
Clarification: 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.
6. Resistance R4 is known as ________
a) standard resistance
b) unknown resistance to be measured
c) resistance arm
d) input resistance
Clarification: 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.
7. What is connected between the two ends of a Wheatstone bridge?
a) current and voltage source
b) ammeter and voltmeter
c) battery and galvanometer
d) ohmmeter and wattmeter
Clarification: 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.
8. Wheatstone bridge works on the principle of ________
a) full deflection
b) partial deflection
c) no deflection
d) null deflection
Clarification: 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.
9. The balance condition of a Wheatstone bridge depends on the _________
a) ratio of arms R1 and R1
b) ratio of arms R3 and R4
c) emf source and null detector
d) current source and power source
Clarification: 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.
10. Balance condition can be obtained by _________
a) varying the standard resistance R3
b) varying the resistance arms R1 and R2
c) keeping the unknown resistance R4 constant
d) by making use of a null detector
Clarification: 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.