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# Question about a Wheatstone bridge

2018-03-22 13:49:26

Q) Suppose each bridge resistor is capable of dissipating 250mW. Can the bridge be left in the balanced state without exceeding the power-dissipating capacity of the resistors, thereby damaging the bridge?

A) yes

simulate this circuit – Schematic created using CircuitLab

I can't extremely understand why the answer is 'yes'.

As Dampmaskin said, the schematic and values you have posted do not make a balanced bridge. So that makes it difficult to evaluate the circuit based on the premise of a "balanced state" of the question.

However, the only voltage source in the system, is V1 at 5V. We certainly can see how much power a resistor would consume in a worst-case condition of being placed directly across V1. Testing the smallest resistors, R1 and R2:

\\$P=\dfrac{E^2}{R} =\dfrac{5V^2}{100\Omega}=250mW\\$

So balanced or not, you can't really exceed the maximum power ratings.

• As Dampmaskin said, the schematic and values you have posted do not make a balanced bridge. So that makes it difficult to evaluate the circuit based on the premise of a "balanced state" of the question.

However, the only voltage source in the system, is V1 at 5V. We certainly can see how much power a resistor would consume in a worst-case condition of being placed directly across V1. Testing the smallest resistors, R1 and R2:

\\$P=\dfrac{E^2}{R} =\dfrac{5V^2}{100\Omega}=250mW\\$

So balanced or not, you can't really exceed the maximum power ratings.

2018-03-22 14:40:52