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Current Electricity — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity1 Mark
MCQ
A potentiometer can measure emf of a cell because:
  • A
    The sensitivity of potentiometer is large.
  • B
    No current is drawn from the cell at balance.
  • C
    No current flows in the wire of potentiometer at balance.
  • D
    Internal resistance of cell is neglected.
✓

Answer

  1. No current flows in the wire of potentiometer at balance.

Explanation:

Potentiometer is preferred over voltmeter because it measures true emf of the cell. It uses null method so that no current is drawn from cell in balanced condition, as E - Ir = V and I = 0 then V = E.

Hence emf measurement is more accurate.

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