A 7.0 µF capacitor and a 5.0 µF capacitor are connected in series across a 5.0 kV potential difference. The charged capacitors are then disconnected from the source and connected to each other with terminals of like sign together. Find the charge on each capacitor (in mC) and the voltage across each capacitor (in V). (Due to the nature of this problem, do not use rounded intermediate values in your calculations—including answers submitted in WebAssign.)

Respuesta :

Explanation:

Given two capacitors 7.0 µF and 5.0 µF connected in series, let s calculate the effective capacitance.

[tex]\frac{1}{C_T} = \frac{1}{7.0} +\frac{1}{5.0}\\ \frac{1}{C_T} = \frac{5+7}{35} \\C_T = \frac{35}{12}\\ C_T = 2.9166\mu F[/tex]

Given

V = 5.0kV = 5000Volts

To get the total charge in the circuit, we will use the formula:

[tex]Q = C_TV\\Q = 2.9166\times 10^{-6} \times 5000\\Q = 0.014583 C\\Q = 1.4583 \times 10^{-2}C[/tex]

Since the same charge flows in a series connected capacitors, the charge on them in mC is 14.583mC

For the voltage across 7.0 µF:

[tex]V = \frac{Q}{C}\\V = \frac{0.014583}{0.000007} \\V = 2,083.28V[/tex]

Voltage across the 7.0 µF is 2,083.28V

The voltage across the  5.0 µF:

V = 5000 - 2,083.28

V = 2,916.72Volts

Voltage across the  5.0 µF is 2,916.72V

Answer:

The charge on the first capacitor is 14.59 mC

The voltage across the first capacitor is 2084 V

The charge on the second capacitor is 14.59 mC

The voltage across the second capacitor is 2918 V

Explanation:

Given;

first capacitor, C₁ = 7.0 µF

second capacitor, C₂ = 5.0 µF

potential difference, V = 5000 V

The equivalent capacitance is given by;

[tex]\frac{1}{C_{eq}}= \frac{1}{C_1} +\frac{1}{C_2}\\\\\frac{1}{C_{eq}}= \frac{C_1 + C_2}{C_1C_2}\\\\C_{eq} = \frac{C_1C_2}{C_1 +C_2}\\\\ C_{eq} = \frac{(7*10^{-6})(5*10^{-6})}{(7*10^{-6} \ +\ 5*10^{-6})}\\\\C_{eq} = 2.917*10^{-6} \ F[/tex]

The charge on the first capacitor is given by;

[tex]Q_1 = C_{eq} V\\\\Q_1 = 2.917*10^{-6} *5000\\\\Q_1 = 0.01459 \ C\\\\Q_1 = 14.59 \ mC[/tex]

The voltage across the first capacitor is given by;

[tex]V_1 = \frac{Q_1}{C_1} \\\\V_1 = \frac{0.01459}{7*10^{-6}}\\\\ V_1 = 2084.286 \ V[/tex]

V₁ = 2084 V

The charge on the second capacitor is given by;

[tex]Q_2 = C_{eq} V\\\\Q_2 = 2.917*10^{-6} *5000\\\\Q_2 = 0.01459 \ C\\\\Q_2 = 14.59 \ mC[/tex]

The voltage across the second capacitor is given by;

[tex]V_2 = \frac{Q_2}{C_2}\\\\ V_2 = \frac{0.01459}{5*10^{-6}}\\\\V_2 = 2918 \ V[/tex]