Current Electricity Charging Discharging Of Capacitors Question 711
Question: The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of $ 10\Omega $ is
Options:
A) $ 0.5\Omega $
B) $ 0.8\Omega $
C) $ 1.0\Omega $
D) $ 0.2\Omega $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Given: emf $ \varepsilon =2.1V $
$ I=0.2A,R=10\Omega $ Internal resistance $ r=? $ From formula. $ \varepsilon -Ir=V=IR $
$ 2.1-0.2r=0.2\times 10 $
$ 2.1-0.2r=2\text{ or }0.2r=0.1 $
$ \Rightarrow r=\frac{0.1}{0.2}=0.5\Omega $
BETA
