Alevel capacitor help physics
For charge, when a capacitor is discharging why does charge exponentially decay. I thought because a capacitor stores charge, when it discharges it means its letting the charge out, idk right wording for that.
Why does current decrease too, my understanding was if charge is increasing which I thought then if there's more charge there can be a flow of electrons and also V=IR, resistance stays the same and voltage is decreasing so shouldn't current be increasing?
Also, why exponentially.
Can someone help me please?
Why does current decrease too, my understanding was if charge is increasing which I thought then if there's more charge there can be a flow of electrons and also V=IR, resistance stays the same and voltage is decreasing so shouldn't current be increasing?
Also, why exponentially.
Can someone help me please?
Reply 1
Original post
by LisaPereraFor charge, when a capacitor is discharging why does charge exponentially decay. I thought because a capacitor stores charge, when it discharges it means its letting the charge out, idk right wording for that.
Why does current decrease too, my understanding was if charge is increasing which I thought then if there's more charge there can be a flow of electrons and also V=IR, resistance stays the same and voltage is decreasing so shouldn't current be increasing?
Also, why exponentially.
Can someone help me please?
Why does current decrease too, my understanding was if charge is increasing which I thought then if there's more charge there can be a flow of electrons and also V=IR, resistance stays the same and voltage is decreasing so shouldn't current be increasing?
Also, why exponentially.
Can someone help me please?
More charge leads to a higher voltage (V = Q/C), which leads to a higher current (I = V/R), which leads to faster discharge.
As the charge decreases, so do the voltage and current, slowing down the discharge.
Why does the current decrease?
During discharge, the charge decreases (it does not increase!).
Charge Q decreases ==> Voltage V decreases ==> Current I decreases.
According to Ohm's law (V = IR), "I" must also decrease if "R" is constant and "V" decreases.
Why exponential?
The discharge rate is proportional to the remaining charge: dQ/dt = -Q/(RC).
This produces Q(t) = Q°e^(-t/RC).
Analogy: It is like emptying a water tank through a hole; the more water there is, the greater the pressure and the faster the water flows out.
Ciao,
Sandro
Quick Reply
Related discussions
- Can someone help me find PMT mark scheme for alevel physics capacitors
- Capacitor question
- capacitors alevel physics aqa
- Capacitance alevel physics help
- Discharging a Capacitor
- Charging a capacitor with another capacitor
- Physics question help capacitance
- Physics capacitor discharging/charging equations help
- Energy stored in a capacitor
- Unit 4 IAL physics capacitance lesson Question doubt
- Unit 1 engineering design for hnc... Ideas
- OCR A-level Physics B (Advanced Physics) Paper 1 - 23rd May 2025 [Exam Chat]
- Please someone help, im so confused
- Discussion with teacher exponential growth vs decay
- SQA higher physics prediction
- Capacitor question
- Rate A-Levels
- OCR A-level Physics A Paper 2 - 9th June 2025 [Exam Chat]
- Struggling to understand how this equation has been worked out
- Is it worth doing Physics AS?
Latest
Trending
Last reply 8 months ago
Help with british physics olympiad compuational challenge (BphO)Last reply 9 months ago
Is anyone trying to qualify for the International physics OlympiadLast reply 12 months ago
British Physics Olympiad (BphO) round 1, November 2024Physics Study Help
33
108
How The Student Room is moderated
To keep The Student Room safe for everyone, we moderate posts that are added to the site.
