Current Electricity - Result Question 22
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]
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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]
c3eec34ec6b1fad69db54a20ad4b2dca40c2aa54 (a) 10
(b) 11
(c) 9
(d) 20
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Answer:
Correct Answer: 23. (a)
Solution:
- (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, $n=10$
