While measuring the unknown resistance the help of slide wire bridge a greatest accuracy can be achieved when__________________?
Correct answer: C. the balance point is close to the middle of the wire
- A. a most sensitive galvanometer is used
- B. a steady voltage cell is used
- C. the balance point is close to the middle of the wire
- D. a high resistance box is used in one of its gap
Explanation
In a slide-wire bridge, accuracy is greatest when the balance point is near the middle, because the two wire lengths and their measurement errors are then comparable and the percentage error is minimized. The likely wrong choice is a, since a sensitive galvanometer helps detect balance but does not itself minimize the ratio error.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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