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Current Electricity — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity5 Marks
Question
While doing an experiment with potentiometer (Fig.) it was found that the deflection is one sided and (i) the deflection decreased while moving from one end A of the wire to the end B; (ii) the deflection increased. while the jockey was moved towards the end B.
  1. Which terminal +or -ve of the cell $E_1,$ is connected at X in case (i) and how is $E_1$ related to E?
  2. Which terminal of the cell $E_1$ is connected at X in case (ii)?
✓

Answer

  1. If the current in auxiliary circuit (lower circuit containing primary cell) decreases, and potential difference across A and jockey/increases. Then deflection in galvanometer is one sided and the deflection decreased, while moving from one end 'A' of the wire to the end 'S'. And clearly this is possible only when positive terminal of the cell $E_1$ is connected at X and $E_1 > E.$
  2. If the current in auxiliary circuit increases, and potential difference across A and jockey J increases. Then also deflection in galvanometer is one sided. And this is possible only when negative terminal of the cell $E_1$ is connected at X.

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