際際滷

際際滷Share a Scribd company logo

Capacitors

Download as PPTX, PDF
S
Seid Pashayev

Capacitors store electric charge and are made of two conducting plates separated by an insulating material. They have many applications including in electronics like cameras and power surge protectors. The amount of charge a capacitor can store is proportional to the voltage across its plates and depends on factors like the plate area, distance between plates, and the insulating material. Capacitors can be connected in series or parallel in circuits. In series, the capacitance is the reciprocal of the sum of the reciprocals of the individual capacitances. In parallel, the total capacitance is the sum of the individual capacitances.

1 of 22
Downloaded 82 times
Capacitors Qafqaz Univeristeti: Fizika mullimliyi(eng): Sid 永温温霞艶厩
What is capacitor?????? Anyone can say??? Yes we are listening to you
Capacitors Capacitors have many applications: Computer RAM memory and keyboards. Electronic flashes for cameras. Electric power surge protectors. Radios and electronic circuits.
Electronic Components Capacitors are electronic components that store charge efficiently They can be charged and discharged very quickly and hold their charge indefinitely Symbol
The structure of the capacitor Capacitors are made from two parallel metal plates separated by an insulator called a dielectric In practice they appear a little more complex
Capacitors and Capacitance Charge Q stored: CVQ The stored charge Q is proportional to the potential difference V between the plates. The capacitance C is the constant of proportionality, measured in Farads. Farad = Coulomb / Volt A capacitor in a simple electric circuit.
Capacitance (symbol C) Capacitance is the amount of charge a capacitor can store when connected across a potential difference of 1V (the larger the capacitance the more charge it can store) Units of capacitance are Farads (symbol F) 1 Farad = 1 coulomb per volt This is a lot of charge!! most capacitors are small; 袖F (1 x 10-6 F) nF (1 x 10-9 F) pF (1 x 10-12 F) V Q C Where; C=Capacitance in Farads (F) Q=Charge in Coulombs (C) V=Voltage in Volts(V)
Exercises 1. Calculate the capacitance of a capacitor that stores 1.5 10-9C at 7.2V?
Capacitance (C) Three factors determine capacitance; 1. The area of the plates (CA) 2. The distance separating the plates (C ) 3. The properties of the dielectric (竜r) so C= constant x d 1 d A
If there is air or a vacuum between the plates the constant is; the absolute permittivity of free space (symbol 竜0) (竜0 = 8.84 x 10-12 Fm-1) so; d A C 0 Capacitor Construction Formula
When an insulator (dielectric) is placed between the plates the capacitance increases The dielectric constant (symbol 竜r) gives the proportion by which the capacitance will increase so; and therefore Note that 竜r has no units as d A C or ワ airrdielectic CC 器 air dielectric r C C 緒 Insulator 竜r Air 1 Polystyrene 2.5 Glass 6.0 Water 80 Capacitor Construction Formula
1-PLATE AREA: All other factors being equal, greater plate area gives greater capacitance; less plate area gives less capacitance. 2-PLATE SPACING: All other factors being equal, further plate spacing gives less capacitance; closer plate spacing gives greater capacitance.
3-DIELECTRIC MATERIAL: All other factors being equal, greater permittivity of the dielectric gives greater capacitance; less permittivity of the dielectric gives less capacitance.
Examples 1. Calculate the capacitance of a capacitor with a polystyrene dielectric (竜r =2.5), an area of 1.2cm by 3.2m and a plate separation of 8 micrometers. d A C or ワ (竜0 = 8.84 x 10-12 Fm-1)
Combination of capacitors
Capacitors in Parallel V C1 C2 Q C V When capacitors are joined at both ends like this, they are said to be in parallel They have the same voltage across them They can be treated like a single capacitor: 1 1 2 2 Q C V Q C V 1 2Q Q Q 1 2C C V 1 2C C C When capacitors are joined at one end, with nothing else, they are said to be in series They have the same voltage across them They can be treated like a single capacitor: V C 1C 2 1 1 2 2 Q C V Q C V 1 2 Q Q C C 1 2V V V Q C 1 2 1 1 1 C C C Capacitors in Series
Series and Parallel When two circuit elements are connected at one end, and nothing else is connected there, they are said to be in series 1 2 1 1 1 C C C When two circuit elements are connected at both ends, they are said to be in parallel 1 2C C C C1 C2 C1 C2 These formulas work for more than two circuit elements as well. C1 C2 C3 C4 C5 1 2 3 4 5 1 1 1 1 1 1 C C C C C C
Examples 1. A circuit has three 330 亮F capacitors in series. Calculate the total capacitance of the circuit 2. Another circuit has three 330 亮F capacitors in parallel. Calculate the total capacitance of the circuit.
Find the equivalent capacitance seen between terminals a and b of the circuit in Figure.
Solution: :seriesinarecapacitorsF5andF20 F4 520 520 F6with theparalleliniscapacitorF4 :capacitorsF20and F302064 緒 withseriesiniscapacitorF30 capacitor.F60the F20F 6030 6030 eqC
Problems solve at home: 1. A 330亮F capacitor is charged by a 9.0V battery. How much charge will it store? 2. A 0.1亮F capacitor stores 1.5 10-7 C of the charge. What was the voltage used to charge it? 3. Calculate the plate area required for a 1000 亮F, glass (竜r=6.0) capacitor, with a plate separation of 2.8 micrometres. 4. Calculate the dielectic constant of a 10000 亮F capacitor with a 1.2亮m plate separation and an area of 16.97m2
Calculate effective capacitance: a b 15 亮F 3 亮F 6 亮F What is the effective capacitance Cab between points a and b? 20 亮F C1 C2 C3 C4 Cab ?

More Related Content

Capacitors

  • 2. What is capacitor?????? Anyone can say??? Yes we are listening to you
  • 3. Capacitors Capacitors have many applications: Computer RAM memory and keyboards. Electronic flashes for cameras. Electric power surge protectors. Radios and electronic circuits.
  • 4. Electronic Components Capacitors are electronic components that store charge efficiently They can be charged and discharged very quickly and hold their charge indefinitely Symbol
  • 5. The structure of the capacitor Capacitors are made from two parallel metal plates separated by an insulator called a dielectric In practice they appear a little more complex
  • 6. Capacitors and Capacitance Charge Q stored: CVQ The stored charge Q is proportional to the potential difference V between the plates. The capacitance C is the constant of proportionality, measured in Farads. Farad = Coulomb / Volt A capacitor in a simple electric circuit.
  • 7. Capacitance (symbol C) Capacitance is the amount of charge a capacitor can store when connected across a potential difference of 1V (the larger the capacitance the more charge it can store) Units of capacitance are Farads (symbol F) 1 Farad = 1 coulomb per volt This is a lot of charge!! most capacitors are small; 袖F (1 x 10-6 F) nF (1 x 10-9 F) pF (1 x 10-12 F) V Q C Where; C=Capacitance in Farads (F) Q=Charge in Coulombs (C) V=Voltage in Volts(V)
  • 8. Exercises 1. Calculate the capacitance of a capacitor that stores 1.5 10-9C at 7.2V?
  • 9. Capacitance (C) Three factors determine capacitance; 1. The area of the plates (CA) 2. The distance separating the plates (C ) 3. The properties of the dielectric (竜r) so C= constant x d 1 d A
  • 10. If there is air or a vacuum between the plates the constant is; the absolute permittivity of free space (symbol 竜0) (竜0 = 8.84 x 10-12 Fm-1) so; d A C 0 Capacitor Construction Formula
  • 11. When an insulator (dielectric) is placed between the plates the capacitance increases The dielectric constant (symbol 竜r) gives the proportion by which the capacitance will increase so; and therefore Note that 竜r has no units as d A C or ワ airrdielectic CC 器 air dielectric r C C 緒 Insulator 竜r Air 1 Polystyrene 2.5 Glass 6.0 Water 80 Capacitor Construction Formula
  • 12. 1-PLATE AREA: All other factors being equal, greater plate area gives greater capacitance; less plate area gives less capacitance. 2-PLATE SPACING: All other factors being equal, further plate spacing gives less capacitance; closer plate spacing gives greater capacitance.
  • 13. 3-DIELECTRIC MATERIAL: All other factors being equal, greater permittivity of the dielectric gives greater capacitance; less permittivity of the dielectric gives less capacitance.
  • 14. Examples 1. Calculate the capacitance of a capacitor with a polystyrene dielectric (竜r =2.5), an area of 1.2cm by 3.2m and a plate separation of 8 micrometers. d A C or ワ (竜0 = 8.84 x 10-12 Fm-1)
  • 16. Capacitors in Parallel V C1 C2 Q C V When capacitors are joined at both ends like this, they are said to be in parallel They have the same voltage across them They can be treated like a single capacitor: 1 1 2 2 Q C V Q C V 1 2Q Q Q 1 2C C V 1 2C C C When capacitors are joined at one end, with nothing else, they are said to be in series They have the same voltage across them They can be treated like a single capacitor: V C 1C 2 1 1 2 2 Q C V Q C V 1 2 Q Q C C 1 2V V V Q C 1 2 1 1 1 C C C Capacitors in Series
  • 17. Series and Parallel When two circuit elements are connected at one end, and nothing else is connected there, they are said to be in series 1 2 1 1 1 C C C When two circuit elements are connected at both ends, they are said to be in parallel 1 2C C C C1 C2 C1 C2 These formulas work for more than two circuit elements as well. C1 C2 C3 C4 C5 1 2 3 4 5 1 1 1 1 1 1 C C C C C C
  • 18. Examples 1. A circuit has three 330 亮F capacitors in series. Calculate the total capacitance of the circuit 2. Another circuit has three 330 亮F capacitors in parallel. Calculate the total capacitance of the circuit.
  • 19. Find the equivalent capacitance seen between terminals a and b of the circuit in Figure.
  • 20. Solution: :seriesinarecapacitorsF5andF20 F4 520 520 F6with theparalleliniscapacitorF4 :capacitorsF20and F302064 緒 withseriesiniscapacitorF30 capacitor.F60the F20F 6030 6030 eqC
  • 21. Problems solve at home: 1. A 330亮F capacitor is charged by a 9.0V battery. How much charge will it store? 2. A 0.1亮F capacitor stores 1.5 10-7 C of the charge. What was the voltage used to charge it? 3. Calculate the plate area required for a 1000 亮F, glass (竜r=6.0) capacitor, with a plate separation of 2.8 micrometres. 4. Calculate the dielectic constant of a 10000 亮F capacitor with a 1.2亮m plate separation and an area of 16.97m2
  • 22. Calculate effective capacitance: a b 15 亮F 3 亮F 6 亮F What is the effective capacitance Cab between points a and b? 20 亮F C1 C2 C3 C4 Cab ?