The simplest model capacitor consists of two thin parallel conductive plates separated by a dielectric with permittivity ε . This model may also be used to make qualitative predictions for other device geometries. The plates are considered to extend uniformly over an area A and a charge density ±ρ = ±Q/A exists on their surface. Assuming that the length and width of the plates are much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line integral of the electric field between the plates COUNT 5
QSN1 In an ideal model of a capacitor, what is the value that describes the permittivity of the dielectric? ANS1 permittivity ε QSN2 What equation describes the charge density for an ideal model of a capacitor? ANS2 ±ρ = ±Q/A QSN3 In an ideal model of a capacitor, what must be assumed about the size of the plates? ANS3 much greater than their separation d QSN4 Close to the middle of the capacitor, what equation describes the magnitude of the electric field? ANS4 E = ρ/ε QSN5 What does the line integral of the electric field between the plates of a capacitor represent? ANS5 The voltage