An lc circuit consists of a capacitor with c = 2.9 μf and an inductor with l = 30 mh. at t = 0 the capacitor has charge 6.3 μc and the current in the inductor is zero. the circuit oscillates at its resonant frequency. how long after t = 0 will the current in the circuit be maximum?
what will be this maximum current?

Explanation:

In the L-C oscillation , energy is transferred between capacitor and inductor with a certain periodicity.

Initial energy in the capacitor = 1/2X Q² / C

= 6.84 x 10⁻⁶ J

Initial energy of inductor is zero.

Total energy = 6.84 x 10⁻⁶ J

When all the energy is stored in the inductor , it has maximum current . Let this current be I

Energy of inductor

= 1/2 L I²

Here I is maximum current in the inductor.

Conserving energy

1\2 L I² = 6.84 X 10⁻⁶

.5 X 30 X 10⁻³ I² = 6.84 X 10⁻⁶

I = 2.13 X 10⁻²

= 21.3 mA.

Time period of oscillation

T =

=

188.4 10^{-5}.s

Current will be maximum after 1/ 4 of time period

= .25 x 188.1 x 10⁻⁵ s

47 X  10⁻⁵ s

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.