A student is using a spreadsheet to model the decay of charge on a capacitor.
They are using the equation
ΔQΔt=−Q4.0 \frac{\Delta Q}{\Delta t} = -\frac{Q}{4.0} ΔtΔQ=−4.0QThe student chooses a time interval of 1.0 s. At time t=0.0 st = 0.0\text{ s}t=0.0 s the charge on the capacitor is 800 μC800\text{ }\mu\text{C}800 μC.
Part of the modelling spreadsheet is shown below.
| t / st\text{ / s}t / s | Charge Q Q\,Q left on capacitor after time t / μCt\text{ / }\mu\text{C}t / μC | Charge ΔQ \Delta Q\,ΔQ decaying in the next 1.0 s / μC1.0\text{ s / }\mu\text{C}1.0 s / μC |
|---|---|---|
| 0.0 | 800 | 200 |
| 1.0 | 600 | |
| 2.0 | ||
| 3.0 | ||
| 4.0 |
What is the charge on the capacitor at t=3.0 st = 3.0\text{ s}t=3.0 s?
200 μC200\text{ }\mu\text{C}200 μC
338 μC338\text{ }\mu\text{C}338 μC
378 μC378\text{ }\mu\text{C}378 μC
450 μC450\text{ }\mu\text{C}450 μC
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.