Capacitance increases with larger plate area (more charge can be stored), smaller separation
Capacitors - OCR A-Level Physics
$$C = \frac{\epsilon_0 \epsilon_r A}{d}$$
- CapacitanceThe chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). stored per unit potential difference across a capacitor. Measured in farads (F). increases with larger plate area (more chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). can be stored), smaller separation (stronger electric field), and higher permittivity dielectricAn insulating material placed between the plates of a capacitor that increases its capacitance by reducing the electric field strength for a given chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C)...
- A dielectricAn insulating material placed between the plates of a capacitor that increases its capacitanceThe charge stored per unit potential difference across a capacitor. Measured in farads (F). by reducing the electric field strengthThe force per unit positive charge at a point in an electric field. Measured in N C⁻¹ or V m⁻¹. for a given charge. is an insulating material placed between the plates. Its polar molecules align with the field, reducing the effective field and allowing more charge to be stored at the same voltageThe energyThe capacity to do work. Measured in joules (J). transferred per unit charge between two points. Measured in volts (V). Informal term for potential difference..
- The relative permittivityThe factor by which a dielectric material increases capacitance compared to a vacuum: C = εᵣε₀A/d. $\epsilon$_r tells you how many times more capacitanceThe charge stored per unit potential difference across a capacitor. Measured in farads (F). you get compared to a vacuum.
Common Mistake
MEDIUM
Wrong: Thinking a dielectricAn insulating material placed between the plates of a capacitor that increases its capacitance by reducing the electric field strength for a given charge. increases the electric field between the plates.
Right: A dielectricAn insulating material placed between the plates of a capacitor that increases its capacitance by reducing the electric field strength for a given charge. reduces the electric field between the plates. The aligned polar molecules create an opposing field, reducing the net field and the p.d. for a given charge, so more charge flows on at the same applied voltageThe energyThe capacity to do work. Measured in joules (J). transferred per unit charge between two points. Measured in volts (V). Informal term for potential difference..
Right: A dielectricAn insulating material placed between the plates of a capacitor that increases its capacitance by reducing the electric field strength for a given charge. reduces the electric field between the plates. The aligned polar molecules create an opposing field, reducing the net field and the p.d. for a given charge, so more charge flows on at the same applied voltageThe energyThe capacity to do work. Measured in joules (J). transferred per unit charge between two points. Measured in volts (V). Informal term for potential difference..