Find the Current After the Capacitors Have Lost 80% of Stored Energy

Click For Summary
SUMMARY

The discussion focuses on calculating the current in a circuit after capacitors have lost 80% of their stored energy. Initially, each capacitor has a charge of 3.00 nC. The voltage was incorrectly calculated as 1 x 1024 V, leading to an erroneous current of 4 x 1022 A. The correct approach requires accounting for the 80% energy loss, which was not addressed in the initial calculations.

PREREQUISITES
  • Understanding of capacitor charge and energy storage
  • Familiarity with the formula for voltage (V = Q/C)
  • Knowledge of Ohm's Law (V = IR)
  • Basic circuit analysis techniques
NEXT STEPS
  • Review the concept of energy stored in capacitors and how to calculate it
  • Learn how to determine the voltage drop after a specific percentage of energy loss
  • Study the impact of series and parallel capacitor configurations on total capacitance
  • Practice problems involving current calculations in RC circuits
USEFUL FOR

Students studying electrical engineering, physics enthusiasts, and anyone looking to deepen their understanding of capacitor behavior in circuits.

Northbysouth
Messages
241
Reaction score
2

Homework Statement


In the circuit shown in the figure each capacitor initially has a charge of magnitude 3.00nC on its plates.

A) After the switch S is closed, what will be the current in the circuit at the instant that the capacitors have lost 80.0% of their initial stored energy?

Image attached

Homework Equations


C=Q/V
V-IR


The Attempt at a Solution



Knowing that V = Q/C I tried to calculate the voltage

V = (3x10-9C)(1/15x10-12F + 1/20x10-12F + 1/10x10-12F)

V = 1x1024

Then using V=IR
I = V/R

I got 4x1022

It says this is wrong and I'm not sure what else to try. Help would be appreciated.
 

Attachments

  • physics hwk 7 prob 5.png
    physics hwk 7 prob 5.png
    15.4 KB · Views: 941
Physics news on Phys.org
Your calculated voltage looks awfully high. Better check your arithmetic.

I don't see where you've accounted for the 80% drop in energy.
 

Similar threads

Comparing energy lost by the battery & energy gained by the capacitor.
  • · Replies 5 ·
Replies
5
Views
2K
Ranking charge stored on three capacitors by a battery
  • · Replies 6 ·
Replies
6
Views
3K
LC oscillations - two capacitors and an inductor
  • · Replies 15 ·
Replies
15
Views
1K
Capacitor Questions Charging and Discharging
  • · Replies 4 ·
Replies
4
Views
4K
Determining Inductance L in an LC Circuit
  • · Replies 5 ·
Replies
5
Views
2K
Current through capacitors in parallel
  • · Replies 24 ·
Replies
24
Views
2K
Energy in capacitor at steady state
  • · Replies 10 ·
Replies
10
Views
2K
Need help finding current on RC circuit
  • · Replies 5 ·
Replies
5
Views
7K
The energy stored in a system of capacitors (only)
  • · Replies 1 ·
Replies
1
Views
1K
Maximum current through a capacitor
  • · Replies 1 ·
Replies
1
Views
3K