Electro Magnetic Induction And Alternating Currents Question 104
Question: A resistance of 20 ohms is connected to a source of an alternating potential $ V=220\sin (100\pi t) $ . The time taken by the current to change from its peak value to r.m.s value is [MP PET 2001]
Options:
A) 0.2 sec
B) 0.25 sec
C) $ 25\times {{10}^{-3}} $ sec
D) $ 2.5\times {{10}^{-3}} $ sec
Show Answer
Answer:
Correct Answer: D
Solution:
Peak value to r.m.s. value means, current becomes $ \frac{1}{\sqrt{2}} $ times. So from $ i=i_{0}\sin 100\pi t\Rightarrow \frac{1}{\sqrt{2}}\times i_{0}=i_{0}\sin 100\pi t $
$ \Rightarrow \sin \frac{\pi }{4}=\sin 100\pi t\Rightarrow t=\frac{1}{400}sec $ $ =2.5\times {{10}^{-3}}sec. $
