Electromagnetic Induction and Alternating Current 7 Question 7
7. The amplitude of a damped oscillator decreases to 0.9 times its original magnitude is $5 s$. In another $10 s$, it will decrease to $\alpha$ times its original magnitude, where $\alpha$ equals $\quad$ (2013 Main)
(a) 0.7
(b) 0.81
(c) 0.729
(d) 0.6
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Answer:
Correct Answer: 7. (c)
Solution:
- Amplitude decreases exponentially. In $5 s$, it remains 0.9 times. Therefore, in total $15 s$ it will remains $(0.9)(0.9)$ $(0.9)=0.729$ times its original value.
