A potentiometer wire of length 1 m is connected to a driver cell of emf 3 V as shown in the figure. When a cell of 1.5 V emf is used in the secondary circuit, the balance point is found to be 60 cm. On replacing this cell and using a cell of unknown emf, the balance point shifts to 80 cm.
- Calculate unknown emf of the cell.
- Explain with reason, whether the circuit works, if the driver cell is replaced with a cell of emf 1 V.
- Does the high resistance R, used in the secondary circuit affect the balance point? Justify your answer.
CBSE DELHI - SET 1 2008
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- $\frac{E_1}{E_2} = \frac{l_1}{l_2}$
- No. P.D. across wire AB will not be able to balance 1.5V emf/balance point will not exist on the wire AB.
- No. At balance point no current is drawn from the cell. Balance point is independent of R.
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