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Question : 7
Total: 26
A 10 V cell of negligible internal resistance is connected in parallel across a battery of emf 200 V and internal resistance 38 Ω as shown in the figure. Find the value of current in the circuit.
OR
In a potentiometer arrangement for determining the emf of a cell, the balance point of the cell in open circuit is350 cm . When a resistance of 9 Ω is used in the external circuit of the cell, the balance point shifts to 300 cm . Determine the internal resistance of the cell.
OR
In a potentiometer arrangement for determining the emf of a cell, the balance point of the cell in open circuit is
Solution:
Writing the equation
Finding the current
By Kirchoff's law, we have, for the loop ABDC,
200 − 38 i − 10 = 0
∴ i =
A = 5 A
OR
Stating the formula
Calculatingr
We have,r = (
− 1 ) R = (
) R
∴ r = (
) × 9 Ω
=
× 9 Ω = 1.5 Ω
Finding the current
By Kirchoff's law, we have, for the loop ABDC,
OR
Stating the formula
Calculating
We have,
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