meter bridge

Question

In a meter bridge, a known resistance of 6 Ω in the right gap is balanced by an unknown resistance in the left gap. If the balance point is at 40 cm from the left end, what is the unknown resistance?

RankGuru · Accepted Answer

1. **Bridge Balance Condition**: $\frac{R}{S} = \frac{l}{100 - l}$.
2. **Identify Given Data**: 
   - Balance length from left $l = 40 	ext{ cm}$.
   - Resistance in right gap $S = 6 	ext{ } \Omega$.
   - Unknown in left gap $R = ?$
3. **Calculation**:
   - $\frac{R}{6} = \frac{40}{60} = \frac{2}{3}$
   - $R = 6 	imes \frac{2}{3} = 4 	ext{ } \Omega$.
4. **Conclusion**: The unknown resistance is 4 Ω.

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meter bridge

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