If the resistance R4 in a Wheatstone bridge is decreased, what effect does it have on the balance condition?
Correct Answer: The bridge becomes unbalanced.
- Step 1: Understand what a Wheatstone bridge is. It is a circuit used to measure unknown resistances by balancing two legs of a bridge circuit.
- Step 2: Identify the components of the Wheatstone bridge. It has four resistors: R1, R2, R3, and R4, and a power source.
- Step 3: Know the balance condition. The bridge is balanced when the ratio of R1 to R2 is equal to the ratio of R3 to R4 (R1/R2 = R3/R4).
- Step 4: Recognize what happens when R4 is decreased. If R4 becomes smaller, the ratio R3/R4 increases because R3 stays the same.
- Step 5: Compare the ratios. Since R1/R2 remains the same, but R3/R4 increases, the two ratios are no longer equal.
- Step 6: Conclude that the bridge is unbalanced. Decreasing R4 disturbs the balance condition of the Wheatstone bridge.
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