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When a 360 nF air capacitor is connected to a power supply, the energy stored in the capacitor is 1.85 x 10-5 J. While the capacitor is kept connected to the power supply, a slab of dielectric is inserted that completely fills the space between the plates. This increases the stored energy by 2.32 x 10-5 J. (a) What is the potential difference between the capacitor plates

Sagot :

Answer:

(a) Approximately [tex]10.1\; {\rm V}[/tex].

Explanation:

Let [tex]C[/tex] denote the capacitance of a capacitor. Let [tex]V[/tex] be the potential difference (voltage) between the two plates of this capacitor. The energy [tex]E[/tex] stored in this capacitor would be:

[tex]\displaystyle E = \frac{1}{2}\, C\, (V^{2})[/tex].

Rearrange this equation to find an expression for the potential difference [tex]V[/tex] in terms of capacitance [tex]C[/tex] and energy [tex]E[/tex]:

[tex]\begin{aligned}V^{2} &= \frac{2\, E}{C} \end{aligned}[/tex].

[tex]\begin{aligned}V &= \sqrt{\frac{2\, E}{C}} \end{aligned}[/tex]

The capacitance [tex]C[/tex] of this capacitor is given in nanofarads. Convert that unit to standard unit (farads):

[tex]\begin{aligned}C &= 360\; {\rm nF} \\ &= 360\; {\rm nF} \times \frac{1\; {\rm F}}{10^{9}\; {\rm nF}} \\ &= 3.60 \times 10^{-7}\; {\rm F}\end{aligned}[/tex].

Given that the energy stored in this capacitor is [tex]E = 1.85 \times 10^{-5}\; {\rm J}[/tex], the potential difference across the capacitor plates would be:

[tex]\begin{aligned}V &= \sqrt{\frac{2 \times 1.85 \times 10^{-5}\; {\rm J}}{3.60 \times 10^{-7}\; {\rm F}}} \\ &\approx 10.1\; {\rm V}\end{aligned}[/tex].