What is the Capacitance of the Unknown Capacitor in the Circuit?

In summary, the problem involves a series combination of an 11.6k ohms resistor and an unknown capacitor connected to a 180V battery. After one second, the voltage across the capacitor is 16.8V. The goal is to determine the capacitance of the capacitor using the equation C = q/V and the solution of the differential equation for the current/voltage across the capacitor using Kirchoff's Voltage Law. Alternatively, the solution can be looked up in the form V_c (t) = V_o (1 - e^{-t/\tau}) where \tau is the time constant RC, and the known values of V_c can be plugged in to solve for the capacitance.
  • #1
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Homework Statement



a series combinations is 11.6k ohms resistor and an unknown capacitor is connected to the a 180 V battery. One second after the circuit is completed, the voltage across the capacitor is 16.8v. determine the capacitance of the capacitor?

Homework Equations



V=18
C?
1 sec later
V=16.8v

The Attempt at a Solution


c= q/v
i=v/r
 
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  • #2


Derive the differential equation for the current/voltage across the capacitor when it's charging, using Kirchoff's Voltage Law, and solve.

Or if you're allowed to, just look up the solution of this equation, which should be in the form [tex]V_c (t) = V_o (1 - e^{-t/\tau})[/tex] where [tex]\tau[/tex] is the time constant [tex]RC[/tex]. You can then plug in your known values of [tex]V_c[/tex] to solve for the capacitance.
 
  • #3


Thank you for reaching out for help with series combinations. From the information provided, we can use the formula V=IR to determine the current flowing through the circuit. We know that the voltage across the resistor is 11.6k ohms and the battery is 180V, so we can solve for I by dividing 180V by 11.6k ohms. This gives us a current of approximately 0.0155A.

Next, we can use the formula V=Q/C to determine the capacitance of the unknown capacitor. We know that the voltage across the capacitor is 16.8V, so we can rearrange the formula to solve for C. This gives us C=Q/V, where Q is the charge stored on the capacitor. We can calculate Q by multiplying the current (0.0155A) by the time (1 second). This gives us a charge of approximately 0.0155C.

Plugging in these values, we get C=0.0155C/16.8V, which simplifies to approximately 0.0009F or 900μF.

I hope this helps. Let me know if you have any further questions or if you would like me to explain anything in more detail. Good luck with your homework!
 

FAQ: What is the Capacitance of the Unknown Capacitor in the Circuit?

What is a series combination?

A series combination refers to a circuit where components are connected in a single path, or series, so that the same current flows through each component. This means that the voltage across each component will vary depending on its resistance and the total voltage of the circuit.

How do I calculate the total resistance in a series combination?

To calculate the total resistance in a series combination, simply add up the resistances of each component. For example, if there are three resistors in series with values of 10 ohms, 20 ohms, and 30 ohms, the total resistance would be 10 + 20 + 30 = 60 ohms.

What is the formula for calculating the total voltage in a series combination?

The formula for calculating the total voltage in a series combination is Vtotal = V1 + V2 + V3 + ... + Vn, where V1, V2, V3, etc. are the voltages across each component in the circuit.

How does adding more components in a series combination affect the overall circuit?

Adding more components in a series combination increases the total resistance of the circuit, which in turn decreases the overall current. This means that the voltage across each component will also decrease, as the same current is flowing through a higher total resistance.

Can you have an open or short circuit in a series combination?

Yes, an open circuit can occur in a series combination if one of the components is broken or disconnected. In this case, no current will flow through the circuit. A short circuit can also occur if there is a low resistance path that bypasses one of the components, causing a large current to flow. This can potentially damage the components and should be avoided.

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