A student is modelling the decay of the potential difference across a discharging capacitor using the discrete approximation equation:
ΔVΔt=−0.05V \frac{\Delta V}{\Delta t} = -0.05 V ΔtΔV=−0.05Vwhere V V\,V is the potential difference across the capacitor in volts and t t\,t is the time in seconds. The student decides to use a time interval of Δt=3.0 s\Delta t = 3.0\text{ s}Δt=3.0 s. The initial potential difference at t=0 st = 0\text{ s}t=0 s is 12.00 V.
Part of the student's modelling table is shown below:
| t / st\text{ / s}t / s | Potential difference V / VV\text{ / V}V / V | Decrease in potential difference ΔV \Delta V\,ΔV in the next 3.0 s / V |
|---|---|---|
| 0 | 12.00 | 1.80 |
| 3.0 | 10.20 | |
| 6.0 | ||
| 9.0 |
What is the modelled value of V V\,V at t=9.0 st = 9.0\text{ s}t=9.0 s?
6.60 V6.60\text{ V}6.60 V
7.37 V7.37\text{ V}7.37 V
7.65 V7.65\text{ V}7.65 V
10.29 V10.29\text{ V}10.29 V
22 exam-style questions on OCR A A Level Physics Capacitors, covering Capacitors, Energy, and Charging and discharging capacitors. Each one has a worked solution and a mark scheme showing where the marks go.