Wheatstone Bridge Concepts and Calculations

The video tutorial explains the concept of a Wheatstone bridge, a circuit used to measure low resistance values. It covers how to calculate the unknown resistor Rx in a balanced Wheatstone bridge by using proportional resistances. The tutorial includes a practice problem to reinforce the concept. Additionally, it discusses how to calculate the voltage reading of a voltmeter in an unbalanced Wheatstone bridge circuit, emphasizing the use of voltage dividers and the impact of high resistance in voltmeters.

What is the condition for a Wheatstone Bridge to be considered balanced?

• The current through the ammeter is maximum.

• The resistors on one side are equal to the resistors on the other side.

• The voltage across the bridge is zero.

• The current through the ammeter is zero.

In a balanced Wheatstone Bridge, if R1 is 30 ohms and R3 is 60 ohms, what should be the value of Rx if R2 is 70 ohms?

• 35 ohms

• 70 ohms

• 60 ohms

• 140 ohms

Which law is used to derive the formula for calculating Rx in a Wheatstone Bridge?

• Faraday's Law

• Kirchhoff's Voltage Law

• Ohm's Law

• Coulomb's Law

What is the formula for Rx in terms of R1, R2, and R3 in a balanced Wheatstone Bridge?

• Rx = R3 * R2 / R1

• Rx = R1 * R3 / R2

• Rx = R2 * R3 / R1

• Rx = R1 * R2 / R3

In the practice problem, if R2 is 16 ohms and R1 is 48 ohms, what is the value of Rx when R3 is 60 ohms?

• 25 ohms

• 40 ohms

• 20 ohms

• 30 ohms

What is the main difference between a balanced and an unbalanced Wheatstone Bridge?

• The voltage across the bridge

• The type of resistors used

• The current through the ammeter

• The presence of a voltmeter

In an unbalanced Wheatstone Bridge, what is the potential difference read by the voltmeter if Vc is 36 volts and Vd is 28 volts?

• 36 volts

• 28 volts

• 64 volts

• 8 volts

Why is the current through a voltmeter considered negligible?

• Because it has a very low resistance

• Because it is connected in parallel

• Because it has a very high resistance

• Because it is connected in series

What is the potential at point C if the voltage across R2 is 36 volts?

• 60 volts

• 28 volts

• 36 volts

• 0 volts

If the potential at point D is 28 volts, what is the source voltage if R4 is 7 ohms and R3 is 8 ohms?

• 16 volts

• 36 volts

• 28 volts

• 60 volts