| Cue / Question | Notes |
|---|---|
| Formula for parallel plate capacitor (vacuum) | C = ε_{0}A/d |
| Formula with dielectric | C = Kε_{0}A/d; K = dielectric constant (≥1) |
| Series combination formula | 1/C_eq = 1/ + 1/ + ... |
| Parallel combination formula | C_eq = + + ... |
| Which capacitor in series has more energy? | Smaller C (since Q same; U = /2C, smaller C → larger U) |
| Which capacitor in parallel has more energy? | Larger C (since V same; U = ½, larger C → larger U) |
| Three forms of energy stored | U = ½ = /(2C) = ½QV |
| Battery connected, plates pulled apart (d doubled)? | C halves; Q = CV halves; U = ½ halves |
| Battery disconnected, plates pulled apart (d doubled)? | Q stays same; C halves; V doubles; U = /2C doubles |
Summary: Capacitor questions in NEET always test either the combination rules or what happens when the battery is connected vs disconnected during modification (dielectric insertion, plate separation change). Master both scenarios: connected → V constant, disconnected → Q constant.