Current Electricity - Result Question 22

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23. A set of ’ $n$ ’ equal resistors, of value ’ $R$ ’ each, are connected in series to a battery of emf ‘E’ and internal resistance ’ $R$ ‘. The current drawn is I. Now, the ’n’ resistors are connected in parallel to the same battery. Then the current drawn from battery becomes $10 I$. The value of ’n’ is [2018]

======= ####23. A set of ’ $n$ ’ equal resistors, of value ’ $R$ ’ each, are connected in series to a battery of emf ‘E’ and internal resistance ’ $R$ ‘. The current drawn is I. Now, the ’n’ resistors are connected in parallel to the same battery. Then the current drawn from battery becomes $10 I$. The value of ’n’ is [2018]

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/current-electricity/current-electricity—result-question-22.md (a) 10

(b) 11

(c) 9

(d) 20

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Answer:

Correct Answer: 23. (a)

Solution:

  1. (a) In series grouping equivalent resistance $R _{\text{series }}=nR$

In parallel grouping equivalent resistance

$R _{\text{parallel }}=\frac{R}{n}$

$I=\frac{E}{n R+R}$

$10 I=\frac{E}{\frac{R}{n}+R}$

Dividing eq. (ii) by (i),

$ 10=\frac{(n+1) R}{(\frac{1}{n}+1) R} $

Solving we get, $n=10$