A 8.00-μF capacitor that is initially uncharged is connected in series with a 3.00-Ω resistor and an emf source with E = 70.0 V and negligible internal resistance. At the instant when the resistor is dissipating electrical energy at a rate of 300 W, how much energy has been stored in the capacitor?

Respuesta :

Answer:

The energy stored is [tex]E_s = 0.0064 \ J[/tex]

Explanation:

From the question we are told that  

   The capacitance  is  [tex]C = 8 \ \mu F = 8*10^{-6} \ F[/tex]

    The resistance is  R = 3.00-Ω

    The emf is  [tex]E_t = 70.0 V[/tex]

      The power  is  P = 300 W

Generally the total  emf is mathematically represented as

   [tex]E_t = E_c + E_r[/tex]

Here  [tex]E_c[/tex] is the emf across that capacitor which is mathematically represented as

      [tex]E_c = \frac{q}{C}[/tex]

and [tex]E_r[/tex] is the emf across the resistor which is mathematically represented as

       [tex]E_r = \sqrt{P R}[/tex]

So  

       [tex]E_t = \sqrt{PR} + \frac{q}{C}[/tex]

=>    [tex]q = C[E_t - \sqrt{PR} ][/tex]

Generally the energy stored in a capacitor is mathematically represented as

          [tex]E_s = \frac{q^2}{2C}[/tex]

=>      [tex]E_s = \frac{[C [ E_t - \sqrt{PR} ]]^2}{2C}[/tex]

=>      [tex]E_s = \frac{[8.0*10^{-6} [ 70 - \sqrt{300 * 3}}{2 *(8.0*10^{-6})}[/tex]

=>      [tex]E_s = 0.0064 \ J[/tex]

The energy that has been stored in the capacitor will be 0.0064 J. The stored energy is utilized in the different electrical works.

What is a capacitor?

A capacitor is a device that can store electrical energy. It is a two-conductor configuration separated by an insulating medium that carries charges of equal size and opposite sign.

An electric insulator or vacuum, such as glass, paper, air, or a semi-conductor termed a dielectric, can be used as the non-conductive zone.

The given data in the problem is;

C is the capacitance = 8.00-μF = 8.00 ×10 ⁻⁶

R is the resistance =  3.00-Ω

E is  the emf  = 70.0 V

P is the power  = 300 W

The total emf is the sum of the emf due to the capacitor and emf due to the resistor;

[tex]\rm E_t = E_C + E_R[/tex]

The emf generated by the capacitor is;

[tex]\rm E_C = \frac{q}{C}[/tex]

[tex]\RM E_R = \sqrt{PR}[/tex]

[tex]\rm E_t = \frac{q}{C} + \sqrt{PR} \\\\ \rm q= C [ E_t-\sqrt{PR} ]\\\\[/tex]

Generally, the energy stored in the capacitor is;

[tex]\rm E_S= \frac{q^2}{2C} \\\\ \rm E_S= \frac{\rm C [ E_t-\sqrt{PR} ]\\\\^2}{2C} \\\\ \rm E_S= \frac{\rm 8.0 \times 10^{-6}[ 70-\sqrt{300\times 3} ]\\\\^2}{2 \times (8.0 \times 10^{-6}} \\\\ \rm E_S= 0.0064 \ J[/tex]

Hence the energy that has been stored in the capacitor will be 0.0064 J.

To learn more about the capacitor refer to the link;

https://brainly.com/question/14048432