I am stuck on some critical thinking questions on Capacitance. I will work out the problem to see if I can get it right. Please do correct my mistakes along the way. I would appreciated it if someone can help me correcting my mistakes:
1. If Vs = 25V, Vc1= 10V, Vc2= 15V, CT=10 uF, determine each capacitance value in this series capacitive circuit.
I do know Q= V*C. So Q=25V * 10 uF = 250 uC. C=Q/V, C1 = 250uC/10V = 25uC, C2 = 250 uC/15V = 16.66 uC.
2. Two capacitors ( one 1 uF, the other unknown) are charged from a 12V source. The 1 uF cap is charged to 8V, the other to 4V. What is the value of the other capacitor?
In the chapter I was taught this formula Vx = Ct/Cx * Vs. Obviously this formula doesn't apply to this question. I know I can't find QT unless I know CT and VT, so I'm stumped on this question.
3. A 10 kHz voltage source is applied to a .0047 uF capacitor. 1 mA of rms current is measured. What is the value of the voltage?
I know V= I/XC. XC = 1/2*pi*f*C. So 1/6.28*10kHz*.0047uF = 3.38 kilo Ohm. V= 1 mA * 3.38 Kilo Ohm = 3.38 V.
4. A certain capacitor stores 50 millijoules of energy when charged to 12 V, what is the capacitance value?
I was taught this formula where Energy = 1/2*C*V^2. This question is one where I just don't know what steps to take to find the right answer.
Thanks again!
1. If Vs = 25V, Vc1= 10V, Vc2= 15V, CT=10 uF, determine each capacitance value in this series capacitive circuit.
I do know Q= V*C. So Q=25V * 10 uF = 250 uC. C=Q/V, C1 = 250uC/10V = 25uC, C2 = 250 uC/15V = 16.66 uC.
2. Two capacitors ( one 1 uF, the other unknown) are charged from a 12V source. The 1 uF cap is charged to 8V, the other to 4V. What is the value of the other capacitor?
In the chapter I was taught this formula Vx = Ct/Cx * Vs. Obviously this formula doesn't apply to this question. I know I can't find QT unless I know CT and VT, so I'm stumped on this question.
3. A 10 kHz voltage source is applied to a .0047 uF capacitor. 1 mA of rms current is measured. What is the value of the voltage?
I know V= I/XC. XC = 1/2*pi*f*C. So 1/6.28*10kHz*.0047uF = 3.38 kilo Ohm. V= 1 mA * 3.38 Kilo Ohm = 3.38 V.
4. A certain capacitor stores 50 millijoules of energy when charged to 12 V, what is the capacitance value?
I was taught this formula where Energy = 1/2*C*V^2. This question is one where I just don't know what steps to take to find the right answer.
Thanks again!
Last edited: