A capacitor in an LC oscillator experiences a maximum potential difference of 88V and a maximum energy of 2002 uJ. At a certain instant the energy in the capacitor is 125 uJ. At that same instant the potential difference across the capacitor is closest to:

Explanation:

maximum energy of capacitor

E = 1/2 C V ²

C is capacitance of capacitor and V is potential difference

given V = 88 V

E = 2002 x 10⁻⁶ J

Putting the values

2002 x 10⁻⁶ = 1/2 x C x 88²

C = .517 x 10⁻⁶ F  .

In the second case

Energy E = 125 x 10⁻⁶ J .

C = .517 x 10⁻⁶

V =  ?

E = 1/2 C V ²

125 x 10⁻⁶  = 1/2 x  .517 x 10⁻⁶ x V²

V² = 483.55

V = 21.98 V .

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speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.