Discharging capacitor half life

In summary: RC/\log_e(2)In summary, the half life of a discharging capacitor is the time it takes for the voltage to decrease to half of its original value. This can be mathematically represented by the equation v = V_0\, 2^{-\frac{t}{\log(2) \, RC}}, where RC \, \log_e(2) is the half life constant. This concept is applicable in various processes of decay and growth.
  • #1
Googl
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What is meant by discharging capacitor half life (the description). I seem to be getting different description, I would just like for someone to confirm it here for me please.
 
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  • #2
If discharged through a resistor the capacitor voltage reduces exponentially via the equation

[tex] v = V_0 \, e^{-\frac{t}{RC}}[/tex]

Mathematically it's easy to represent an exponential of one base in other other base.

In this case the above exponential can be re-written as

[tex] v = V_0\, 2^{-\frac{t}{\log(2) \, RC}}[/tex]

where "log" is the natural logarithm.

From the above equation you can see that the "half life" is [itex]RC/\log_e(2)[/itex]
 
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  • #3
Thanks Uart,

I understand that, how would you describe half life (not mathematically or through equations).

uart said:
If discharged through a resistor the capacitor voltage reduces exponentially via the equation

[tex] v = V_0 \, e^{-\frac{t}{RC}}[/tex]

Mathematically it's easy to represent an exponential of one base in other other base.

In this case the above exponential can be re-written as

[tex] v = V_0\, 2^{-\frac{t}{\log(2) \, RC}}[/tex]

where "log" is the natural logarithm.

From the above equation you can see that the "half life" is [itex]RC/\log_e(2)[/itex]
 
  • #4
Googl said:
Thanks Uart,

I understand that, how would you describe half life (not mathematically or through equations).

Well obviously, it's the time that you have to wait until the voltage is half of it's original value. That's how I'd describe it.
 
  • #5
Half life of a quantity is the time it needs so that the quantity is reduced to half of its original value.

In the example of Uart, half life of the voltage is the time it gets for the voltage to reduce to the half of its starting value , that is the time it needs to go from [tex]V_0[/tex] to [tex] \frac{V_0}{2}[/tex]
 
  • #6
Thanks.
 
  • #7
It may be worthwhile pointing out that this 'half life' applies wherever you start. So, every period of one half life decreases the voltage by a factor of two. This 'exponential' function is the only one with this property afaik. It applies in many examples of decay and growth processes (even bloody compound interest!).
 
  • #8
uart said:
you can see that the "half life" is [itex]RC/\log_e(2)[/itex]


Just correcting a typo above. That should of course have been [itex]RC \, \log_e(2)[/itex]
 

FAQ: Discharging capacitor half life

1. What is the half-life of a discharging capacitor?

The half-life of a discharging capacitor is the amount of time it takes for the voltage across the capacitor to decrease to half of its original value.

2. How is the half-life of a discharging capacitor calculated?

The half-life of a discharging capacitor can be calculated using the formula t1/2 = 0.693 * (R * C), where R is the resistance in ohms and C is the capacitance in farads.

3. How does the resistance affect the half-life of a discharging capacitor?

The higher the resistance, the longer the half-life of a discharging capacitor will be. This is because a higher resistance slows down the rate at which the capacitor discharges.

4. Can the half-life of a discharging capacitor be changed?

Yes, the half-life of a discharging capacitor can be changed by altering either the resistance or the capacitance of the circuit. A higher resistance or capacitance will result in a longer half-life.

5. How does the half-life of a discharging capacitor affect the functionality of electronic devices?

The half-life of a discharging capacitor is an important factor in determining the functionality and reliability of electronic devices. If the half-life is too short, the device may not function properly or may require frequent maintenance. A longer half-life can ensure the stability and longevity of the device.

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