Capacitor aka condenser

this presentation is about basics of capacitor

1. CONDENSER

2. OBJECTIVE OF LECTURE Principle, construction and how charge is stored in the capacitor E lectrical properties of a capacitor S everal types of capacitors Charging and discharging of capacitors Capacitive reactance Uses

3. Composed of two conductive plates separated by an insulator (or dielectric). Commonly illustrated as two parallel metal plates separated by a distance, d. C = e A/d where e = e r e o e r is the relative dielectric constant e o is the vacuum permittivity CAPACITORS

4. Capacitance increases with increasing surface area of the plates, decreasing spacing between plates, and increasing the relative dielectric constant of the insulator between the two plates. EFFECT OF DIMENSIONS

5. Charge separation in a parallel-plate capacitor causes an internal electric field. A dielectric (orange) reduces the field and increases the capacitance. EFFECT OF DIELECTRIC ON CAPACITANCE

6. Ceramic capacitor Electrolytic capacitor Tantalum capacitor Silver Mica capacitor Polystyrene capacitor Metallised polyester film Polycarbonate capacitor Polypropylene capacitor Glass capacitor Supercapacitor TYPES OF CAPACITORS

7. The basic construction of all capacitors is similar. The construction of capacitor is very simple. A capacitor is made of two electrically conductive plates placed close to each other, but they do not touch each other. These conductive plates are normally made of materials such as aluminium, brass, or copper. CONSTRUCTION

8.   In a simple parallel-plate  capacitor , a voltage applied between two conductive plates creates a uniform  electric field  between those plates. The  electric field  strength in a  capacitor  is directly proportional to the voltage applied and inversely proportional to the distance between the plates. ELECTRIC FIELD OF CAPACITOR

9. CHARGING AND DISCHARGING OF CAPACITOR V c When the V c becomes equal to power supply voltage V the capacitor is fully charged. When the capacitor discharges across the resistor R the voltage V c gradually decreases and drops to zero.

10. The product of resistance R and the capacitance C is called the time constant t . t = R * C A fully charged capacitor discharges to 63% of its voltage after one time period. After 5 time periods it has almost completely discharged all of its voltage. Hence time taken to discharge = 5*time constant TIME OF DISCHARGE OF CAPACITOR

11. Time taken to discharge the capacitor is, =R × C =(3k ) × (1000 F) = 3 sec × 5 = 15 seconds r DURATION OF DISCHARGE

12. Capacitive reactance   (X C ) is a measure of a  capacitor's  opposition to AC. Like resistance it is measured in ohms, but it’s more complex than resistance because its value depends on the. frequency (f) of the electrical signal passing through the  capacitor  as well . CAPACITIVE REACTANCE

13. Capacitors are installed across many circuits & switching points to absorb voltage fluctuation. Energy storage Power conditioning Coupling and Decoupling Motor starters Oscillators Time dependent circuits USES OF CAPACITORS