Calculate Unknown Resistance in Meter Bridge with End Corrections
A meter bridge is set-up as shown, to determine an unknown resistance '' using a standard resistor. The galvanometer shows null point when tapping-key is at mark. The end-corrections are and respectively for the ends and . The determined value of '' is

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Topics & Concepts
Step-by-Step Solution
To determine the unknown resistance using a meter bridge, we use the principle of a balanced Wheatstone bridge.
At the null point, the ratio of the resistances in the two gaps is equal to the ratio of the resistances of the corresponding wire segments:
Since the resistance of a uniform wire is directly proportional to its effective length, we include the end corrections and for ends and , respectively:
Given data:
- Standard resistance,
- Distance of the null point from end ,
- Remaining length of the wire towards end ,
- End-correction at end ,
- End-correction at end ,
Substitute these values into the bridge equation:
Solving for :
Thus, the determined value of is .
Correct Option: B