KAPASITOR DAN INDUKTOR

Capacitors A basic capacitor has two parallel plates separated by an insulating material A capacitor stores an electrical charge between the two plates The unit of capacitance is Farads (F) Capacitance values are normally smaller, such as µF, nF or pF

Capacitors Basic capacitor construction Dielectric material Plate 1 Plate 2 The dielectric material is an insulator therefore no current flows through the capacitor

Capacitors Storing a charge between the plates Electrons on the left plate are attracted toward the positive terminal of the voltage source This leaves an excess of positively charged holes The electrons are pushed toward the right plate Excess electrons leave a negative charge _ + _

CAPACITOR CHARGING

CAPACITOR DISCHARGING

Capacitors Types of capacitors The dielectric material determines the type of capacitor Common types of capacitors are: – Mica – Ceramic – Plastic film

Capacitors Some capacitors are polarised, they can only be connected one way around Electrolytic capacitors are polarised

Standard Units of Capacitance Microfarad (μF) 1μF = 1/1,000,000 = = F Nanofarad (nF) 1nF = 1/1,000,000,000 = = F Picofarad (pF) 1pF = 1/1,000,000,000,000 = = F

Capacitors Variable capacitors are used in communication equipment, radios, televisions and VCRs They can be adjusted by consumers by tuning controls Trimmers are internal adjusted capacitors that a consumer cannot adjust

Capacitors These variable capacitors would be difficult to squeeze into your mobile phone and iPod Current technology uses semi-conductor variable capacitors called varactors (varicaps)

Capacitors The capacitance in a varactor is created when a purpose diode is reversed biased Adjusting the reverse bias alters the capacitance value A simple radio receiver using varactor

INDUKTOR Biasanya berupa kawat yang dililitkan pada inti padat atau tanpa inti. Nama lainnya adalah choke (meneruskan arus dengan frekuensi tertentu dan menghalangi arus pada frekuensi yang lebih tinggi), coil atau solenoid (menghasilkan medan magnet dari arus yang lewat lilitan).

CARA KERJA Induktor menyimpan energi listrik dalam bentuk medan magnet. Perubahan aliran listrik yang melalui induktor menghasilkan medan magnet. Jika laju aliran listrik menurun maka medan magnet juga menurun, akibatnya energi akan dilepaskan dalam bentuk arus listrik meninggalkan induktor

FARADAY’S LAW OF ELECTROMAGNETIC INDUCTION If a conductor is moved through a magnetic field so that it cuts magnetic lines of flux, a voltage will be induced across the conductor The greater the number of flux lines cut per unit Time or the stronger the magnetic field strength, the greater will be the induced voltage across the conductor. Increase the number of magnetic flux lines by increasing the speed with which the conductor passes through the field Equation for voltage induced across a coil if a coil of N turns is placed in the region of a changing flux

Faraday’s law induced voltage equation If the flux linking the coil ceases to change = is the instantaneous change in flux (in webers) N = number of turns of the coil & Equation for inductance of the coils N = number of turns µ = permeability of the core A = area of the core in square meters l = the mean length of the core in meters. µ is not a constant but depends on the level of B and H, since µ = B/H µ is not a constant but depends on the level of B and H, since µ = B/H

Properties of an Inductor Acts like an short circuit at steady state when connected to a d.c. voltage or current source. Current through an inductor must be continuous – There are no abrupt changes to the current, but there can be abrupt changes in the voltage across an inductor. An ideal inductor does not dissipate energy, it takes power from the circuit when storing energy and returns it when discharging.

Properties of a Real Inductor Real inductors do dissipate energy due resistive losses in the length of wire and capacitive coupling between turns of the wire.

KONVENSI TANDA

Relative size of different types of inductors

Inductors in Series

L eq for Inductors in Series

Inductors in Parallel

L eq for Inductors in Parallel

General Equations for L eq Series Combination Parallel Combination If S inductors are in series, then If P inductors are in parallel, then:

Typical areas of application for inductive elements