What Resistor Value Discharges a Capacitor 99% in 5 Seconds?

  • Thread starter Kajan thana
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Using the equation V=Vo*e^(-t/RC), where Vo is the initial voltage, R is the resistance, C is the capacitance, and t is the time, we can solve for R to find the resistance needed for the discharge to be 99% complete in 5 seconds. This results in an estimated resistance of 995x10^5 ohms.
  • #1
Kajan thana
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Homework Statement


.50uf capacitor is charged connecting it to a 6.0v battery then discharged through 100k ohm resistor.
. Question: Estimate the resistance of the resistor that you would use in place of the 100k ohm resistor if the discharge is to be 99% completed within about 5 secs.

Homework Equations



cf8fbc5ea72dc057fbc63976e4083353.png


The Attempt at a Solution


I used voltage instead of charge.

99% of 6V in 5.94V which is discharged in 5 seconds.

5.94/6= e^-5/CR

Then make the R the subject gave 995x10^5 ohm. The answer is wrong, help me please.
 
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  • #2
Kajan thana said:

Homework Statement


.50uf capacitor is charged connecting it to a 6.0v battery then discharged through 100k ohm resistor.
. Question: Estimate the resistance of the resistor that you would use in place of the 100k ohm resistor if the discharge is to be 99% completed within about 5 secs.

Homework Equations



cf8fbc5ea72dc057fbc63976e4083353.png


The Attempt at a Solution


I used voltage instead of charge.

99% of 6V in 5.94V which is discharged in 5 seconds.

5.94/6= e^-5/CR

Then make the R the subject gave 995x10^5 ohm. The answer is wrong, help me please.
The discharge is 99% complete when the charge or voltage on the capacitor is 1% of the initial value.
 
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Related to What Resistor Value Discharges a Capacitor 99% in 5 Seconds?

1. What is a capacitor and how does it work?

A capacitor is an electronic component that stores electrical energy in the form of an electric charge. It consists of two conductive plates separated by an insulating material, known as a dielectric. When a voltage is applied to a capacitor, it creates an electric field between the plates, causing one plate to accumulate a positive charge and the other to accumulate a negative charge. This creates a potential difference, or voltage, between the plates, allowing the capacitor to store energy.

2. How do you discharge a capacitor?

To discharge a capacitor, you need to connect its two terminals together to create a closed circuit. This allows the stored charge to flow from one plate to the other, equalizing the potential difference between them. This can be done using a resistor, a short circuit, or by simply touching the two terminals together.

3. Why is it important to discharge capacitors before working on electronic circuits?

Capacitors can store a significant amount of electrical energy, which can pose a danger to anyone working on electronic circuits. If a charged capacitor is accidentally touched, it can deliver a powerful shock, causing injury or even death. Therefore, it is important to discharge capacitors before working on circuits to ensure safety.

4. How long does it take for a capacitor to discharge?

The time it takes for a capacitor to discharge depends on its capacitance and the resistance in the discharge circuit. Larger capacitors with higher capacitance will take longer to discharge compared to smaller capacitors. The presence of a resistor in the circuit will also slow down the discharge process.

5. Can a capacitor discharge on its own?

Yes, a capacitor can discharge on its own due to its natural leakage of charge over time. This is known as self-discharge and can occur due to imperfections in the dielectric material or external factors such as temperature and humidity. However, the discharge rate is usually very slow and may take days or even weeks for a capacitor to fully discharge on its own.

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