ELEC1310 Lecture Notes - Lecture 9: Electric Field

• School: University of Newcastle
• Department: Electrical Engineering
• Course: ELEC1310
• Professor: Colin Coates

Document Summary

Consists of: two conducting surfaces (often flat (cid:494)plates(cid:495), dielectric (insulator) between plates. Circuit symbols (curved symbol implies polarisation, with the curved side being a reference voltage. Capacitance is the charge stored for a given voltage. Current in a capacitor is the rate of change of charge storage which is proportional to the rate of change of voltage. Voltage is proportional to change which is proportional to the accumulation (integration) of current. Voltage cannot change instantaneously, otherwise i(t) . Capacitors can be used to (cid:498)smooth(cid:499) voltage variations: short-circuiting a capacitor is dangerous, remove electrical noise. Fast changes of voltage require large currents. Current entering and leaving capacitor are the same. No charges accumulate between the plates: charge accumulates on one side and the opposite charge accumulates on the other side. The capacitor voltage must be a continuous function of time. The current through the capacitor is zero. Voltage is equal across each parallel branch.