Video narration
Isliye oscillation lagbhag samanya SHM jitni tez rehti hai, par uski amplitude ki outer envelope lagatar ghatati hai: A = A0 exp[-bt/(2m)]. Sawal energy ke e guna ghatne ka nahin hai. Sawal amplitude ke e-fold ka hai, yani amplitude A0 se ghatkar A0/e hone ka. Isliye A/A0 = 1/e rakhiye. Exponential mein exponent minus one hona chahiye, atah bt/(2m) = 1, aur e-fold time t = 2m/b milta hai. Ab is samay ko oscillations mein badalna hai. Weak damping mein period ko lagbhag undamped period le sakte hain: T approx 2pi sqrt(m/k). Isliye oscillation count hai N = t/T = R sqrt(mk)/(pi B^2l^2). Ab values rakhen: R = 10 ohm, m = 0.050 kilogram, k = 0.5 newton per metre, B = 0.1 tesla, aur l = 0.10 metre. Unit conversion mein centimetre ko metre aur gram ko kilogram karna zaroori hai. In values ko substitute karne par N lagbhag 22.5 aata hai. Arthat amplitude e ke factor se ghatne tak patti kareeb 22 oscillations poore karti hai.