Calculating Capacitance from Voltage-Time Data

In summary, the task at hand is to plot a curve of In (1 - V/Vo) vs time and use the slope of the line to calculate C. The initial equation provided is V = Vo(1-e^-t/RC) and the calculated linear equation is In (1 - V/Vo) = -t/RC. Using the equation y = mx + b, where m is the slope, we can determine that C = -t/Rm. The given values are m = -72.673, R = 10 000 ohms, and C = unknown. The time constant, t, is needed to complete the calculation and is likely to be found by plotting all of the data (t and
  • #1
jdog6
17
0
This is for a lab I have done and I am stuck on this,

Question : Plot a curve of In (1 - V/Vo) vs time and calculate C from the slope of the line.

Initial equation = V = Vo(1-e^-t/RC)
Calculated Linear Equation : In (1 - V/Vo) = -t/RC
Therefore from y = mx + b = m = -t/RC (i think)
Then, C = -t/Rm

m = -72.673
R = 10 000 ohms
C = what we are looking for
-t = ? do i use any of my times

Also, C (accepted value) = 6000x10^-6 Farad
Therefore, answer should be near this.

Please help me out! I'm totally stumped. Thank you.
 
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  • #2
Can anybody help?
 
  • #3
i believe i have a lead t = time constant but i don't know what that is...
 
  • #4
Yes you must plot all of your data. At each time, t, you measured some voltage, v,. Plot the points t, and

[tex] \ln ( 1 - \frac v v_0 ) [/tex]

where v is your measured values. You should get something linear, find the slope of the line.
 

Related to Calculating Capacitance from Voltage-Time Data

What is a capacitor and how does it work?

A capacitor is an electronic component that stores electric charge. It consists of two conductive plates separated by an insulating material, known as a dielectric. When a voltage is applied to the capacitor, one plate accumulates positive charge and the other accumulates negative charge. The capacitor can then store this charge until it is needed.

What is the unit of measurement for capacitor capacity?

The unit of measurement for capacitor capacity is Farads (F). However, capacitors are commonly measured in microfarads (μF) or picofarads (pF) due to their small sizes. 1 Farad is equal to 1 coulomb of charge per 1 volt of potential difference.

What factors affect the capacity of a capacitor?

The capacity of a capacitor is affected by the surface area of its plates, the distance between the plates, and the type of dielectric material used. Generally, the larger the surface area and the closer the plates are to each other, the higher the capacity of the capacitor will be. Different dielectric materials also have different levels of capacitance.

How is the capacity of a capacitor calculated?

The capacity of a capacitor can be calculated using the formula C = Q/V, where C is the capacitance in Farads, Q is the charge stored on the plates in Coulombs, and V is the voltage applied to the capacitor in Volts. This formula can be rearranged to calculate Q or V if the other two values are known.

What is the maximum capacity of a capacitor?

The maximum capacity of a capacitor is determined by its physical size and the dielectric material used. Larger capacitors and those with higher dielectric constants can have higher capacities than smaller ones. However, there is no absolute maximum capacity for a capacitor as it can be increased by connecting multiple capacitors in parallel.

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