Verified Solution • 2025–26 Session
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QNEET-2024-Ph-154: NEET 2024 Physics - Class 12 NEET-2024-Ph-154 Solution: The amplitude of the charge oscillating in a circuit decreases…
The amplitude of the charge oscillating in a circuit decreases exponentially as where is the charge at t=0 s. The time at which charge amplitude decreases to is nearly: [Given that ] 19.01 ms 11.09 ms 19.01 s 11.09 s
Multiple Choice Options
- A 19.01 ms
- B 11.09 ms
- C 19.01 s
- D 11.09 s
Step-by-Step Verified Solution
The given equation for the amplitude of the charge oscillating in a circuit is:
Q = Q 0 e _ R t 2 L
We need to find the time, t , at which charge amplitude decreases to 0.50 Q 0 . So, we set Q = 0.50 Q 0 :
0.50 Q 0 = Q 0 e _ R t 2 L
Divide both sides by Q 0 :
0.50 = e _ R t 2 L
Take the natural logarithm on both sides to solve for t :
ln _ ( 0.50 ) = _ R t 2 L
Recall that ln _ ( 0.50 ) = _ ln _ ( 2 ) . Substituting the given value ln _ ( 2 ) = 0.693 , we get:
_ 0.693 = _ R t 2 L
Remove the negative signs from both sides:
0.693 = R t 2 L
Now, solve for t :
t = 2 L _ 0.693 R
Substituting the given values R = 1.5 � and L = 12 mH = 12 _ 10 _ 3 H , we have:
t = 2 _ 12 _ 10 _ 3 _ 0.693 1.5
Calculate the numerator and denominator:
t = 16.632 _ 10 _ 3 1.5
Finally, compute the value of t :
t = 11.09 _ 10 _ 3 s = 11.09 ms
Therefore, the time at which the charge amplitude decreases to 0.50 Q 0 is nearly 11.09 ms. Thus, the correct answer is:
Option B: 11.09 ms