Question about charged capacitors and inserting a dielectric into one

AI Thread Summary
When a charged capacitor is connected to a battery, it accumulates charge until the potential difference matches that of the battery, at which point current stops. Upon removing the battery and inserting a dielectric, the capacitance increases, reducing the potential difference across the capacitor. This causes the second capacitor to behave like a battery, supplying charge to the first capacitor until their potential differences equalize. The conservation of charge is maintained during this process, and setting up equations before and after the dielectric insertion can help determine the new voltage. The provision of charge continues until the potential differences of both capacitors are equal.
Kaushik
Messages
282
Reaction score
17
Homework Statement
The parallel combination of two air filled parallel plate capacitors of capacitance ##C## and ##nC## is connected to a battery of voltage, ##V##. When the capacitors are fully charged, the battery is removed and after that a dielectric material of dielectric constant ##K## is placed between the two plates of the first capacitor. The new potential difference of the combined system is?
Relevant Equations
##Q = CV##
##C_{eq}= C_1 + C_2## for parallel
## \frac{1}{C_{eq}}= \frac{1}{C_1} + \frac{1}{C_2}## for series
First when it is connected to the battery, the capacitors start accumulating charges such that the potential difference equals that of the battery. Then the current stops flowing.
##Q_1 = CV##
##Q_2 = nCV##
Where 1 and 2 represent the capacitor with capacitance C and nC respectively

Then, when we remove the battery and add a dielectric between the capacitor of capacitance ##C## (##C_{new} = KC##), the potential difference across it reduces. Now, the capacitor 2 starts behaving like a battery, providing charge to the capacitor 1.
After this, how can I proceed?
 
Physics news on Phys.org
Kaushik said:
providing charge to the capacitor 1
And when does this 'provision' come to an end ?
 
  • Like
Likes Kaushik
BvU said:
And when does this 'provision' come to an end ?
When the potential difference between capacitor 1 and capacitor 2 become equal?
 
Correct.
And what is conserved during this provision process ?
Set up a set of equations before and after to find the new ##V##.
 
  • Informative
Likes Kaushik
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top